Tri-Z Engines

[El Camexican]

Finally have all the bits to build the engine I’ve always wanted for my Tri Z. Cylinder goes in for a sleeve next week.

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[floydechoes2000]

Looking forward to this build!

[El Camexican]

Looking forward to this build!

Me too!

Pulled the studs tonight and confirmed what I’d suspected ever since I found out that YZ pistons are taller than Tri-Z pistons.

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No, it’s not that blonds are more fun than redheads, it’s that the YZ cylinder is a little taller. So for anyone pondering the Tri Z Wrench Report head modification AND a YZ piston l, make sure you check you squish band as you’re decreasing it twice as much with both mods.

[yaegerb]

Blinds are way more fun than redheads IMO.....

[El Camexican]

I really need to stop using this talk to type feature

[El Camexican]

Aftermarket Exhaust Spring Tabs. 12ga. steel. Contoured to the shape of the cylinder and guaranteed to out last your trike. Available in yellow or silver.

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After they are installed you can bend them to suit any clearance issues or to adjust the tension on your springs.

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I guess you could say that I’m selling them, but I have no idea how I would get them to anybody at this point. They would be cheap though, no more than $8.00 per pair plus shipping. If interested let me know and we’ll figure something out.

[NeverLift]

Welcome to the PV-Z club. I sure could use a couple of those spring tabs.

[El Camexican]

Welcome to the PV-Z club. I sure could use a couple of those spring tabs.

Silver or yellow? PM me your phone # again and I'll call you next week.

[El Camexican]

Took longer than expected to ship it to Kustom Kraft as I wanted to save on shipping by sending 3 cylinders out in one big big, but it’s back now.

I lucked out and got away with another bore instead of the expected sleeve job.


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Hoping to cleanup the ports over the holidays.

[bkm]

Looks good man and the spring tabs are really nice. Having despised Yamaha for most of my life, I feel that I've missed out on owning one of these bikes in running condition.

[El Camexican]

Looks good man and the spring tabs are really nice. Having despised Yamaha for most of my life, I feel that I've missed out on owning one of these bikes in running condition.

The one you did have for a short while had a lot of rare parts. Whatever happened to that trike?

[bkm]

The one you did have for a short while had a lot of rare parts. Whatever happened to that trike?Got smart and traded it for a 250r.

[El Camexican]

My three wheel obsession has been reactivated by a future ride, so last night the cases on the soon to be PV engine were opened up.

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Got a chance to use my dowel puller, sure beats Vise Grips.

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I soon came to realize that there was a hack inside this thing.

Sesame Street song playing.... One of the things does not belong.

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Glad it didn’t ruin the cover, these things are selling for stupid money.

Then I tried to get the sprocket nut off only to find out someone had put a tiny spot of weld on it to the lock washer. It was almost impossible to see, but the burn hole on the washer was the give away.

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The cherry on the cupcake was finding that they’d welded the shift drum follower wheel solid.

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Seems the bearing on the shift drum (which can’t be replaced) is seized, so off to eBay I went. I hope the shift forks aren’t bent as the guide is bent and the shift shaft was hard to get out.

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Here’s where we’re at now.

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[ironchop]

Wow, that escalated quickly

Sent from my Z958 using Tapatalk

[Aulbaugh]

Hopefully you’ve found all the hacks an everything else goes smooth for you. Where you able to find a replacement shift drum?

[El Camexican]

Wow, that escalated quickly

Sent from my Z958 using Tapatalk

I’ve only got 13 months to finish!

[El Camexican]

Hopefully you’ve found all the hacks an everything else goes smooth for you. Where you able to find a replacement shift drum?

Yes sir, $30 bucks for a drum and follower.

Made a lowball offer on a minty starter lever as well and the seller accepted. Starting to put together a nice collection of starters and clutch covers, I just wish I’d have started it 15 years ago before someone decided there was gold in them.

[El Camexican]

Tonight was output shaft night.

Disassembled it, knocked off all the sharp edges, lapped all the washers and clips and polished the bits.

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[El Camexican]

Tonight was.... you guessed it, input shaft night.

No surprises other than realizing the LGI aka Last Guy In (Remember that, I plan to use it in the future) used silicon to seal the cases :crazy:

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Having time to spare I decided to debur and buff up the crank before I take it in to PG Racing.

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Cost me part of a thumb nail, but it was worth it to feel the adrenaline slowly oozing into my bloodstream as I realized I’d lifted the nail off my thumb about 1/8” in from the tip and not just nicked it like I first thought.

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[El Camexican]

Started prepping the cylinder today. First step was to match the cases to the transfer ports.

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The left side was a little trickier. Because the dowels are on the right side cases I had to remove the locating dowels on the cylinder, bolt the cylinder to the left hand side and then slide the right side cylinder out so that I could access the left side.

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No intention of modifying the power band on this engine, but in the event that something has to be changed for whatever reason I’m going to try and lean towards adding to the bottom end rather than the top of the power band.

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Only did one side today. Looks like it could use a few spots of epoxy in a couple places, but because this is the last bore on the cylinder I probably won’t bother as a new sleeve would displace all the questionable spots.

[El Camexican]

Found this last night. Cylinder guy says the sleeve will hold it together just fine, but I don’t like it.

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[ironchop]

^^^^ No me gusta

Sent from my Z958 using Tapatalk

[Aulbaugh]

Ouch! Seeing that are you leaning toward resleeving?

[El Camexican]

Ouch! Seeing that are you leaning toward resleeving?

Na, I’ll try it like that. The sleeve isn’t cracked and the amount of aluminum in that areas is about 3/8” wide and 1/8” thick, so it isn’t like that’s a structural area.

All my Kawasaki KZ 900 and 1000 had cracks running from the valve seats to the spark plug holes. Freaked me out until I found out they all did that. I would not be surprised if many of these Yamaha power valve cylinders of the same year have similar fractures, but if it blows you guys will be the second to know ;)

[El Camexican]

^^^^ No me gusta

Sent from my Z958 using Tapatalk

Your Spanish is getting pretty good buddy, have you been hitting the taco joints?

[ironchop]

Your Spanish is getting pretty good buddy, have you been hitting the taco joints?I haven't hit a taco joint yet BUT I smoked a Girl Scout cookie joint a few months ago [emoji23][emoji23][emoji23]. Does that count?

Sent from my Z958 using Tapatalk

[El Camexican]

I haven't hit a taco joint yet BUT I smoked a Girl Scout cookie joint a few months ago [emoji23][emoji23][emoji23]. Does that count?

Sent from my Z958 using Tapatalk

That’s between you and the local authorities!

[ironchop]

That’s between you and the local authorities!It wasn't here. It was in a dispensary state.
Sent from my Z958 using Tapatalk

[El Camexican]

Almost forgot about this thread.

Amongst a zillion other projects I’ve been dicking with this off and on, but it’s been one step forward and two steps back as of late.

Came to find out that someone attempted to surface the base of the cases with a grinder and jacked them up so bad I was able to slide a .005” feeler gauge between the cylinder and the cases with the cylinder fully torqued down.

So after spending two nights filing and leaping the cases I noticed that the LH case half was cracked. Wanted to cry, but it was my fault for working the parts before cleaning them, so shame on me.

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Fortunately I had some spare case halves and found two that bolted up nice and let the crank spin free, so they are being put into service.

On the first set of cases I had to remove a fair amount of material to match them to the cylinder, so on these I decided to build up the low spots with epoxy instead of removing material as the removal method leaves very little surface for the base gasket after it’s trimmed.

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[El Camexican]

Today I worked up the nerve (took only 3 beers) to add a second boost port to the cylinder. This one is a little trickier than the Tri-Z cylinder because the intake is angled to the left. Eric Gore says to drill a 1/2” hole on this cylinder and I’ve seen the mod. Frankly it looks stupid, so I decided to get a little more creative.

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One small hole as a reference

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Then another

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Unlike the Tri-Z that’s prone to cracking after this mod I don’t think I have anything to worry about. There seems to be more material in this area on the YZ cylinder and the mounting base seems to be thicker as well. Time will tell.

And there it is.

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[yaegerb]

Today I worked up the nerve (took only 3 beers) to add a second boost port to the cylinder. This one is a little trickier than the Tri-Z cylinder because the intake is angled to the left. Eric Gore says to drill a 1/2” hole on this cylinder and I’ve seen the mod. Frankly it looks stupid, so I decided to get a little more creative.

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One small hole as a reference

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Then another

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Unlike the Tri-Z that’s prone to cracking after this mod I don’t think I have anything to worry about. There seems to be more material in this area on the YZ cylinder and the mounting base seems to be thicker as well. Time will tell.

And there it is.

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Can’t see pics el....

[El Camexican]

That’s weird. They were there a little bit ago.

Took them on a new Apple 11 and got a message that I didn’t have permission to post, so I sent them to my old 7 phone and was able to put them up. Will try again.

[El Camexican]

Here goes again.

Crack

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[El Camexican]

Here’s the epoxy setting up in the transfers.

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[El Camexican]

Ok, seems to be working, here’s the rest.

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[El Camexican]

Found a number of voids in the casting that needed epoxy since the last post. Got back on it today and finished it as far as I can without the bottom end and head.

So far the port timing hasn’t been changed and probably won’t. The widths of the transfers have been slightly increased and the angles have been matched, the boost port has been added and the exhaust ports have been polished. Took a little material off the skirts of the sleeve to try and enhance the entry of the fuel mix into the transfers. Jury is still out on whether or not it’s going to cause them to brake.

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[ATC King]

That’s weird. They were there a little bit ago.

Took them on a new Apple 11 and got a message that I didn’t have permission to post, so I sent them to my old 7 phone and was able to put them up. Will try again.

The pictures on the newer phone may be larger, more resolution. I've gotten the same message before, compressed the file an it uploaded. Several free file compression programs available online. Maybe sending them to the other phone compresses them.

[El Camexican]

The pictures on the newer phone may be larger, more resolution. I've gotten the same message before, compressed the file an it uploaded. Several free file compression programs available online. Maybe sending them to the other phone compresses them.

That seems to be what’s happening, thanks!

[El Camexican]

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..........

[Red Rider]

Looks pretty symmetrical.

[El Camexican]

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..........

[Red Rider]

Okay.... So your not checking to see if your boyessen ports are symmetrical. You’re temporarily plugging them, so you can build up the casting around them, or for a smoother transition from cylinder to bottom end?

[El Camexican]

Okay.... So your not checking to see if your boyessen ports are symmetrical. You’re temporarily plugging them, so you can build up the casting around them, or for a smoother transition from cylinder to bottom end?

I was wondering if anyone would notice the silicone in the first photo.

So I’ve been looking at and reading up on the so called Boyesen ports and it seems that angling them downward a bit and putting a divider between them and the rear set of transfer ports aids the piston in drawing mix into the cases as well as better directing the mix up into the cylinder on the downstroke.

The wood dowels will be drilled out when the epoxy is cured so I can follow the angle and get a burr in there.

I’m also planning to trench the cases a bit so that the Boyesen ports really get a nice clear shot at the crank. Should also help lubricate and cool the lower rod bearing a little.

Or maybe it does nothing and grenades on its maiden voyage :lol:

[Red Rider]

I was wondering if anyone would notice the silicone in the first photo.I did, but it didn’t surprise me, as I’ve seen your engine builds before. :p :lol:

Interesting. I thought the diameter of the dowels looked a bit small to be plugging the ports completely. So the silicone is simply holding the dowels in place for the epoxy process? It’s good to you back at this project.


Or maybe it does nothing and grenades on its maiden voyage :lol:Let’s hope that isn’t the case.

[El Camexican]

I thought the diameter of the dowels looked a bit small to be plugging the ports completely. So the silicone is simply holding the dowels in place for the epoxy process?

Yes, just to keep the epoxy from oozing past the dowels. That stuff is a bear to remove.

BTW, ”Vato” Zone of Mexico stopped carrying the standard version of JB Weld :confused:

They only sell the specialty epoxies now, none of which I’d want to do this with. I need to find a source here to get this finished.

[Red Rider]

I just checked VatoZone online (LOL), and my local store says the "original cold weld formula" 2 oz. size is in stock. Need me to mail you some?

[El Camexican]

I’ll check with the hardware places first and if it’s banned in México or something I’ll hit you up, thanks!

[ironchop]

That epoxy doesn't stick to the wood dowel?

[El Camexican]

That epoxy doesn't stick to the wood dowel?

Absolutely, but it’ll be a lot easier for me to run a drillbit through the wood and then start modifying the hole with the die grinder then it would be to try and drill through solid epoxy. It also gives me a nice guide to work with.

[El Camexican]

Grainger Mexico came through with the JB Weld, so that’s on again. Meanwhile I decided to try and recover a cracked clutch cover by having the face machined flat and welding a 6061 plate over it and then gusseting the plate to the more ridged outer edges of the cover.

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Not sure how ghoulish it will look welded up, but if it holds up I’ll live with it, can’t possibly be any uglier that the ones I’ve seen where the welder has chased the cracks all over the cover.

[Red Rider]

Not sure how ghoulish it will look welded up, ...Nice fix! It looks like an alien has attached itself to the clutch cover.

[El Camexican]

You remember that Startrek episode too eh?

[Red Rider]

You remember that Startrek episode too eh?Nope, never got into Star Trek. I was referring to the movie "Alien."

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[El Camexican]

Drilled out the wood dowels and formed the epoxy ports. Got a couple small voids to fill
in, but otherwise pretty happy with the results.

Before
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After
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[El Camexican]

This finally arrived from Sweden, Jap parts from the land of the Husky, go figure.

Turns out it’s still on the original bore and has the OEM slug in it. There’s silicone on the base gasket, so someone was in it to do rings, but it’s still in better shape than Mike Tyson for its age.

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[ironchop]

The internet is both a beautiful thing and a wicked curse.

Without it though, I'd have not built a couple motorcycles and 5 ATCs, to nane just a few things.... In all cases, I've needed parts and knowledge to pull it off for the last twenty years. I'm not to disappointed in not having to wait for swap meets, word of mouth, or the tiny print classified Trader Paper anymore.

Nice score

[El Camexican]

The internet is both a beautiful thing and a wicked curse.

Without it though, I'd have not built a couple motorcycles and 5 ATCs, to nane just a few things.... In all cases, I've needed parts and knowledge to pull it off for the last twenty years. I'm not to disappointed in not having to wait for swap meets, word of mouth, or the tiny print classified Trader Paper anymore.

Nice score

When I think of how many kilos of Japanese aluminum I sold to the scrap dealer before eBay existed I want to cry. If not for the Internet and eBay many of us outside the US would never be able to patch up these old rides, I just wish it had existed sooner.... and not at all. :lol:

[El Camexican]

Got my Frankencover back this weekend. As expected it warped, so now I need to get it all cleaned up, try to stress relive it and then either machine it flat, or bolt it to a set of cases and use a torch trick Ironchop turned me on to.

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PV arm cover had some rash, seems all of them get worn by a hose sheath of some sort on the YZ, so I filled it in with JB Weld.

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[BarnBoy]

Welds look good Nico. How warped is it?

[El Camexican]

Welds look good Nico. How warped is it?

Cover warped .050” down the center. Ironchop sent me a video on how to straighten it, so I plan to try that.

Turns out the guy my machinist guy recommend to weld the cover and a cylinder used an arc welder and rod. I was not happy given I was told it would be TIG welder. It’s going to take a lot of grinding to make it pretty. Same for the cylinder. Had him run some beads on the side where the boost port was added and also to weld a crack where the exhaust snout is attached to the base. Both welds were too ugly to dress completely with a die grinder, I’d have had to remove too much material, so I just took the welds down as little as possible and smoothed them over with epoxy. Once they’re sanded an painted the mods should be invisible unless it’s side by side with a stock cylinder.

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[bobtdms]

Check your cylinder base gasket surface for warpage. I had a guy at the last shop I worked at lay a patch of weld over the 2nd boost port area, it warped the corner of the gasket surface up .025in. Pretty sure it would snap off if torqued down like that.

[El Camexican]

Check your cylinder base gasket surface for warpage. I had a guy at the last shop I worked at lay a patch of weld over the 2nd boost port area, it warped the corner of the gasket surface up .025in. Pretty sure it would snap off if torqued down like that.

Good point for anyone reading this. I forgot to mention that I had the shop take .002” off the top and bottom of the cylinder to be safe.

I always lap the cases, cylinder and head on these because they are seldom flat in my experience and like the man said, welding can warp them.

[BarnBoy]

Are you going to lap it, or use heat to clamp and straighten?

Thats kinda a BS deal, I've never had any luck with the aluminum arc welding. I think it puts a ton of extra heat into the work that is not necessary. But you had a bunch of welding that needed to be done...hard to avoid. Anyhow, looks good. Once you get that taken care of you should be in business.

[El Camexican]

Are you going to lap it, or use heat to clamp and straighten?

Thats kinda a BS deal, I've never had any luck with the aluminum arc welding. I think it puts a ton of extra heat into the work that is not necessary. But you had a bunch of welding that needed to be done...hard to avoid. Anyhow, looks good. Once you get that taken care of you should be in business.

I cleaned up the welds as much as I’m going to and bolted it down to a case half tonight. Then I heated it up as hot as I could get it with a heat gun and then took a propane torch to the welds and gussets in the area where it’s warped. After it cooled off I unbolted it and it looks like I gained about 015” of an inch, which is not enough, so tomorrow I’m going to take it to where I have my oxyacetylene set and put some real heat to it in a couple of strategic points. If I can get it close i’ll have it milled and then run two gaskets.

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[El Camexican]

Machinist took care of the cover and the cylinder I was originally planning to use. Changed the thread title because I’ve got three different builds happening at the same time as well as so some other Tri Z related stuff.

Using the kickstarter and water pump cover surfaces as clamping points the cover cleaned up with a .037” removed off the highest point. The Versa gaskets I have are .019” thick, so I’ll probably need to run 2 or 3 of them to compensate.

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[El Camexican]

This is the cylinder that was for the original build plan. I’ll probably just finish it up and stick it in a box unless I luck into another bottom end.

It’s got a one-off LA Sleeve in it. 68mm stock bore with a bridged exhaust port. It’s also been welded to accept a second boost port. Had the machinist drop an end mill in to allow the stud nut a clean path. Plans to epoxy and blend to make it invisible to all but the the most observant Tri Z aficionado. Had to take .005” off the base to flatten it. I’ll post photos when all the port work is done.

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[El Camexican]

Fired up my nasty blast cabinet and spent most of the morning cleaning up two engine covers Jedi style using only the Force to guide me because I can’t see anything through the window.

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This particular cover (the nasty looking black one in the first photo) is mint aside of a couple tiny scuffs that you have to look for. There aren’t even any scoring marks around the mounting holes caused by over tightening. I didn’t remember buying it until a few days ago when I found it in a parts box.

Going to pack this one up in a carton box and hope I never need to use it.

[ATC King]

Yum! Spare Parts!


I hear ya on the window. I just had a new one cut for mine a few days ago. I've got the stick-on plastic protectors, but the last one didn't stick so well, and eventually the glass got to the point I didn't care, until it was so bad I couldn't hardly see.

$13 and change to have a new one cut in a few minutes. It's going to feel like a new cabinet. :)

[El Camexican]

On a scale of one to fugly it’s a solid nine, but it’s done.

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Filled in the void below the area where the kicker plate bolts on with epoxy, A to cover up some nasty welds and B because it looks like an area that could use a little extra support.

I think this is the one that will go on the PV engine.

[El Camexican]

Interesting..... just got a photo from my Laredo mail guy.... I wonder what that could be:wondering

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[ironchop]

It's go-fast stickers

Those stickers and a boost bottle are good for 1.5 extra ponies

[El Camexican]

Painted another spare cover last night and put together the one I plan to use for the PV engine.

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Sprock SS impeller

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PV governor assembly

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To add PV to the Tri-Z cover you just need to knock out the steel plug and insert a seal that should be included in any seal kit that claims to fit both the YZ250 and the Tri-Z. When you consider the added cost to incorporate this feature into the Tri-Z cover it seems likely that an 87 Tri-Z would have come from the factory with a power valve.

[ATC King]

When you consider the added cost to incorporate this feature into the Tri-Z cover it seems likely that an 87 Tri-Z would have come from the factory with a power valve.

You're telling us, that if production wouldn't have been forced to cease, they would have continued to improve? :)

This 'cease production' has lasted longer than most ceasefires.

[El Camexican]

You're telling us, that if production wouldn't have been forced to cease, they would have continued to improve? :)

This 'cease production' has lasted longer than most ceasefires.

Everything would have continued to be improved with the exception of the Tecate which was perfected by professional racer, engineer, and former member Barnett468 prior to the ban.

[El Camexican]

Off with the old....

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...and on with the new.

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Thank you Yeagerb!

[El Camexican]

This came in too. Chamber was welded up and recut buy Rob Selvy. The plug was dropped and a o-ring added as well.

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[Dirtcrasher]

I haven't ever had my hands on a TriZ clutch cover but I always felt that there's a bigger problem there.

I mean, how many more broken covers do we need to see??

I'd like to see additional hollow dowel pins support that case cover to the center case around the kicker area and the bolts nearest the clutch basket/disc - It seems as it is the cases want to shear apart the 2 different portions of the housing.

Just about every motor I've taken apart has 2 dowel pins that locate the cover (so that thru shafts bearings are on the same plane) and it also adds strength perpendicular to those mounting bolts.

Bolts just hold things together face to face, they do not locate the 2 pieces nor do they add any strength from opposing forces.

When a person kicks a machine over, that case wants to flex downwards and shear in the direction of force. If it had support with more dowel pins in a few bolt holes I don't think they would crack.

I've watched this happen for 15 years and those were my thoughts. If there was enough "meat" you could add a couple of solid dowel pins but I highly doubt that's the case, with the case, in case anyone cares, that's my case..... :lol:

More than likely 2 or 3 more hollow dowel pins 6mm clearance I.D. and 8mm slip fit O.D. would help support the cover.

If anyone has a clutch cover and a right side main case (can be junk, doesn't matter) and would like me to "experiment" on them, I'd be glad to help.


http://www.3wheelerworld.com/attachment.php?attachmentid=266682&d=1613282225

See the 2 dowel pins for the kicker casting? I'd like see 2 dowel pins right next to those but UNDERNEATH the main cover, I bet there are only 2 dowels under there. One on the left and one on the right by the water pump - Wish I had an easy "paint" app on my PC.... But, I think you know what I mean. Or does the little cover move?? I bet that's fine, it's the area behind that kicker area versus the clutch disc are that wants to shear.

[Red Rider]

The plug was dropped and a o-ring added as well.No outer o-ring, or is that on the cylinder?

[El Camexican]

You’re right, two dowels are located one at the rear and another up at the front. There are also two on the kicker shaft cover.

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There are also shims that seem to get left out for some reason when people take these apart and a spring on the worm gear that wears out. So many things can go wrong that lead to a cracked cover including the placement of the the kick lever on the shaft splines and the foot pegs bending.

Anyone wondering how rare these have become need only look at this eBay listing. It’ll be interesting to see if it sells.

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It’s not cracked, but it’s nasty. I know where there’s a nice one for $375 plus shipping if anyone needs one.

[El Camexican]

No outer o-ring, or is that on the cylinder?

Outer o-ring on that head would need to be sort of oval shaped, so instead he recommended a non hardening sealant.

[El Camexican]

One step forward, two steps back....

Cylinder got damaged somewhere amongst the various shops and shippers. More on that later.

I want to make sure the PV setup is 100% before I go any further. Never did buy a complete engine, just a bunch of eBay parts from various sellers and whatever oem I could find. Looks like Some parts are going to have to be machined.

Meanwhile the valve got cleaned up. The before photos are after two hours in a sonic cleaner.

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[El Camexican]

Warning: This will probably be the most boring post I’ve ever put up. Unless you’re really into Tri-Z’s you’re advised not to waste your time reading it.



Today I spent about 3 hours getting part of a kickstarter assembly ready for use. Started by inspecting all the bits and looking for issues. One of the gears had some smeared edges that I wanted to remove and the other gear had a small burr as well.

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er
Might seem like overkill, but with a clutch cover at stake one can’t be too careful.

Thing is that no matter how well made a gear is, there’s always going to be one tooth that’s bigger that all the others, and one that’s going to be smaller than all the others, but the tiny differences aren’t visible until the parts has been used. Once the gears have been broken in with each other the stress loads are equalized and the burrs that were removed are probably not going to return for a long, if at all.

Anyone planning to do this type of thing to transmission gears be warned to stay away from the dogs and slots unless you know what your doing. Any attempt to round their edges could result in the transmission jumping out of gear. If you think there is damage you can send them to a pro for back cutting.

So here’s all the parts laid out after bead blasting and sonic cleaning.

267221

Note the small washer at the end. Yamaha doesn’t sell them anymore and it seems they don’t always find their way back into the motor after the clutch covers have been removed. Probably because the stick to the cover and come off the shaft at times. Make sure your assembly has one.

The other item crucial to the survival of your clutch cover is the open ended spring with the tab next to the large gear. This should be replaced with some frequency. If it gets weak the starter gear won’t turn on the worm shaft and disengage. If this happens when the engine comes to life your clutch cover and a few other components will be destroyed. They cost a couple bucks and Yamaha still sells them, get two.

If your engine has sat for a long time these springs can rust to the gear. I bough an engine once that had that issue. When the owner kicked the engine over he blew a hole in the RH case. I’ve found traces of rust on almost all the ones I’ve inspected. You don’t want to sand or polish the groove as that can allow the spring to be loose, so it’s best to bead blast them.

267222

[El Camexican]

Merry Christmas to all!

Finally got the re-sleeved cylinder back and started working on it. First thing I noticed is that the sleeve is substantially thicker than the cast in factory sleeve, which is great, but it also protrudes into the area that was machined by Yamaha into a spool shape in order to accept the power valve. Not sure what you can make of the photo below, but the dark area with the shiny grinder mark on it (my attempt to shape it with a die grinder) is the new sleeve and it’s invading cylindrical area need for the power valve by about 2mm.

268844

I called the guy that did the sleeve and he said the way they deal with this is to grind the PV to the shape of the new sleeve. I really didn’t want to to start grinding on a very hard to come by part, so I decided to take to to a machine shop and have them run a boring bar in from both sides to get the cylindrical sections back to stock dimensions and then try to blend in the spool shaped area with a grinder.

268845

I’m very happy with the way it came out. The valve turns freely and there are no gaps, or grooves for excessive blow by, or carbon buildup.

268846

268848

Next step was to blend the lower section of the exhaust port with the new sleeve and polish it up.

268847

Then I did the base of the sleeve. I always ask them to return the cylinders without doing any matching. As much as I complain I do enjoy doing the grinding.

Before
268849

After
268850

I need to get the cylinder mounted and check the timing and squish clearance before I start grinding the port windows. Hopefully I’ll have time to get on that soon.

[6spdls1z28]

Merry Christmas to all!

Finally got the re-sleeved cylinder back and started working on it. First thing I noticed is that the sleeve is substantially thicker than the cast in factory sleeve, which is great, but it also protrudes into the area that was machined by Yamaha into a spool shape in order to accept the power valve. Not sure what you can make of the photo below, but the dark area with the shiny grinder mark on it (my attempt to shape it with a die grinder) is the new sleeve and it’s invading cylindrical area need for the power valve by about 2mm.

268844

I called the guy that did the sleeve and he said the way they deal with this is to grind the PV to the shape of the new sleeve. I really didn’t want to to start grinding on a very hard to come by part, so I decided to take to to a machine shop and have them run a boring bar in from both sides to get the cylindrical sections back to stock dimensions and then try to blend in the spool shaped area with a grinder.

268845

I’m very happy with the way it came out. The valve turns freely and there are no gaps, or grooves for excessive blow by, or carbon buildup.

268846

268848

Next step was to blend the lower section of the exhaust port with the new sleeve and polish it up.

268847

Then I did the base of the sleeve. I always ask them to return the cylinders without doing any matching. As much as I complain I do enjoy doing the grinding.

Before
268849

After
268850

I need to get the cylinder mounted and check the timing and squish clearance before I start grinding the port windows. Hopefully I’ll have time to get on that soon.

Looking good man not sure when I’m going to start messing with mine.

[El Camexican]

Got the cylinder on and using stacked feeler gauges as shims concluded I needed to raise it 0.064” in order to get the piston flush with the deck which is required to eliminate the head gasket and use the o-ringed head. I think I can stack a stock .020” gasket on top of one I cut from the thickest gasket paper I have which is .045”.

268858

Next I checked the static “blowdown” with a timing wheel. Please don’t for one second think I have a clue as to how this all works. I’m just trying to find a happy medium between the stock timing and a number highly respected engine builder once shared with me once. If porting knowledge was the recipe for Coca Cola my understanding of it would be that there’s some kind of sugar in it.

268859

After repeated checks I was freaking out over what was coming out as 38 degrees of blowdown, so I put a stock YZ cylinder on it and got 33 degrees. Then just for fun I tossed a Tri-Z cylinder (no power valve) on and got 32.5 degrees.

Being that I wasn’t planning on altering the timing I was hoping to avoid making a port map, but given the 5 degrees difference and how much metal was going to have to be removed in order to get back to 33 degrees.

268860

Turned out the maps were almost identical, within .5mm on most lines, but then I remembered that the sleeved cylinder had been cut at both ends, so a quick check determined that the sleeved cylinder was 0.031” shorter than the stock cylinder. The exhaust was within half a degree of where I wanted it, but I had to raise all the transfer ports about 2.5mm to get the blowdown to 33.5 degrees. Once I’m done chamfering the ports I should have an honest 33 degrees.

268861

268862

[El Camexican]

I don’t remember exactly how long ago, but must’ve been at least a year, I gave a decent condition power valve to a machine shop and asked if they could duplicate it with one important change.

These things are almost as had to find as Tri-z clutch covers. Seems they wear out, or brake where the actuating arm attaches. The squared off shaft is made of the same cast aluminum as the rest of the valve, so if the assembly gets gummed up the thin aluminum tip gets damaged. Pretty safe guest to assume that just as many have been damaged by people trying to extract the power valve out of the cylinder by clamping vice grips on to them as well.

This one is still functional, but it’s pretty rough.

268882

This is the solid steel shaft design I requested. No chance of this braking now.

268883

Here are the two stockers next to the repop.

268884

I had to contour the auxiliary exhaust veins with a grinder, so I thought I’d take it a step further and buff it up a little.

268885

Also had some discontinued bushings made. Will have at least three of everything in stock if I ever want to build another PV engine one day.

268886

[El Camexican]

Cylinder is done. Hope to put it all together soon.

268887

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268893

[coolpool]

I'm getting error messages on the attachments?

FWIW, you have some mad engine building skills my friend! I just assume magic is happening in the silver shiny thing which makes noise and creates smiles.....done:-)

[El Camexican]

I'm getting error messages on the attachments?

FWIW, you have some mad engine building skills my friend! I just assume magic is happening in the silver shiny thing which makes noise and creates smiles.....done:-)

Thanks, let me try that again….

[El Camexican]

Trying to download the photos of post #87

268896

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268904

268901

268902

268903

[El Camexican]

Went to install the cylinder studs last night only to realize that with the decking and eliminating of the head gasket I going to have to shorten the brand new OEM (and freshly plated) studs about 3mm if I want to use acorn nuts. While mulling that over and realizing that even extra tall acorn nuts wouldn’t cut it, I remembered that the YZ engine uses dowel collars. Given that the Tri-Z is famous for head leaks and that the YZ was getting the newest upgrade I decided to drill the Selvy head to suit. Kind of a scary process knowing what it would take to replace it.

268921

After finishing, and realizing that the collars don’t fit the factory holes in the cylinder very tight it occurred to me that they are more so to hold the gasket in place. No matter, it’s done and the head has way less movement on the cylinder than it did.

[ironchop]

Looks fantastic sir

I'll bet you're glad you didn't polish this motor

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[El Camexican]

Looks fantastic sir

I'll bet you're glad you didn't polish this motor

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Yeah, that’s never happening again:crazy:

268924

[this old rz]

Good God! I never realized the Tri Z had so many problems until reading through your posts...lol
Never was able to get my project going.....So glad I didn't jump in head 1st with mine as my bike has been Micky moused 6 ways to next Sunday.
I never would have figured all these shortcomings out.
Rob Selvy built all my friends ATCs 250Rs and Tecates.... I was recently thinking of pulling my for sale ad; and having him do my TriZ, as he had a few custom cool parts for one at his shop.
But now with his passing away....Think I'll leave my TriZ advertised on Craigslist.
Hoping a dedicated individual will seek her out and give her some long overdue justice.

[6spdls1z28]

What did you mill the yz head to?

[ATC King]

Yeah, that’s never happening again:crazy:

268924


WOW!

A Steampunk edition Tri-Z engine. Did you follow through with the design for the rest of the trike?

268975


Looks nice, but I couldn't resist havig some fun in pointing out the coincidence. :beer

[El Camexican]

What did you mill the yz head to?

I did not use a YZ head as the spigot locations are different.

I sent a stock Tri-Z head to Yaeger performance who had Rob Selvy weld up the combustion chamber and machine a completely different chamber.

[El Camexican]

WOW!

A Steampunk edition Tri-Z engine. Did you follow through with the design for the rest of the trike?

268975


Looks nice, but I couldn't resist havig some fun in pointing out the coincidence. :beer

Hopefully they don’t sue me for plagiarism.

http://www.3wheelerworld.com/showthread.php/186109-Polished-Tri-Z-Engine/page4

[El Camexican]

I had planned on checking the squish and timing one last time before I get ready to bolt this thing together when it dawned on me that I had not installed the vacuum port, or elbow if you will for the pressurized fuel system.

The Tri-Z cylinder has a machined flat spot on the cylinder for the elbow, but the YZ does not, so I had to drill the hole at an angle to the curved cylinder. Drilled .004” smaller than the elbow and hammered it in with green Loctite on it.

268993

268994

268995

268996

With that in place, I checked the bore one last time and then both of the cylinder down and Chechen the timing one last time and measured the squish.

Exhaust opens at 83 ATDC and the transfers open at 115 for 32 degrees of blowdown. Squish is .042”

268997

268998

[6spdls1z28]

You get this thing together yet?


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[El Camexican]

You get this thing together yet?


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No sir. Had a few issues come up including a week in bed. Will post when time permits.

[6spdls1z28]

No sir. Had a few issues come up including a week in bed. Will post when time permits.

Feel better looking forward to seeing it together! I have to take my crank to get a new rod put in before I assemble mine.


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[El Camexican]

Re-wired some stators today including one with all new parts from Ricky Stator and eBay. All of them got Shep’s super awesome grommets. Every Tri-Z deserves these. Thank for the consult ps2fixer!

269062

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[El Camexican]

I thought I was just about ready to button this thing up the other day. I started by removing the cast ribs on the stock clutch cover that are known to rub on the aftermarket clutch baskets.

269069

269070


Then I went to setup the power valve only to find out I’d installed the wrong bearing in my finest Tri-Z clutch cover. I tried to remove it, but ended up breaking the puller. At that point it occurred to me that the clutch cover is probably the most expensive and unobtainable part on the engine, so I carefully ground the end of the governor shaft down to 7mm in order to get it to fit the incorrect bearing. By far the most halfassed mod. I’ve made since turning 18, but in my defense, it came out almost perfectly round and fit the bearing nicely.

269071

With that cringe worthy southern engineering event behind me I installed the Sprock impeller and installed the cover. With all the bolts in place I attempted to turn the engine and it wouldn’t budge. For some reason the NOS Yamaha washer that’s supposed to prevent the backside of the water pump impeller from rubbing on the clutch cover was too thick, or maybe the bushing in the case wasn’t pressed in far enough causing the pump gear to bind. Whatever the reason, a thinner washer fixed it.

269074

With the cover secured I went to hook up the PV linkage only to discover once again I was the victim of an ill informed eBay seller. Note the slightly different bends on the arm on the top. Fortunately I had another that came with another 85 cylinder and it fit. As far as the adjustment goes I only have a Clymer manual and it either has a horrible translation, or they copy pasted Info from another manual. If anyone happens to have an honest to God 85 YZ250 manual, or knows what the base line setting is, please let me know. For now I just raised the PV to the open position and scratched a witness line into the bushing. When I rev it up with the cover off I can adjust to match. Given all the adjustments to the cylinder height it’s probably the best way to check it.

269076

269072

Then a nut and wrench had to be modified in order to accommodate the weld that was placed on the rear left corner of the cylinder in order to add a nice big boost port.

269073

So with everything but the head installed I thought I’d check the squish one last time.

269075

Good thing I did because the gaskets compressed enough under full torque that I ended up a little below the safe mark for something that isn’t being rebuilt every week. No combination of my many stock, Sprock, or Auto Zone gasket paper combines to what I need without triple stacking, so I decided to call Cometic. Ended up ordering four .075” rubber coated aluminum gaskets and two .250” aluminum spacers that can be used for future projects. The tech’s name name was Evan and he was a pleasure to deal with.

[knappyfeet]

Aw....the modified wrench.

I have many of those laying around.

Nice modification on the governor shaft....save that clutch cover!

[El Camexican]

One step forward, three steps back.

So I picked up the spacers and gaskets from Cometic and went to install the cylinder on the .075” thick base gasket.

Thought it was kind of odd that the piston was sticking way up over the deck, so I went and measured one of the spare gaskets in the pack.

269221

269219

Needless to say, they will be getting a phone call tomorrow.

269218

Good news is I finally have my hands on two of the coveted cylinder spacers. These are used for long rod motors as well as stroked crankshaft’s. I have neither at the moment, but at least I’ve got spacers if the need ever comes up.

269220

[ATC King]

Needed a couple barley pops after measuring that, did you?

[El Camexican]

Needed a couple barley pops after measuring that, did you?

I’m on my forth rum. Life is short, I just need to take a deep breath and go work on some thing else.

[Red Rider]

Other's incompetence ruining a perfectly good day again!

[El Camexican]

Mystery solved. You may recall I was bragging on the guy from Cometic after placing my order. I’m gonna take that back now. He no longer works there and the guy that replaced him informed me that there’s no way they could’ve built a gasket that thick using coated aluminum.

I explain to him what I needed, and he went to the shop and torqued down one of their new Kevlar reinforced gaskets which has not yet been used for the YZ application. They come fresh at .080” and compress about .002”, So with no additional charges they are going to send me four of them on Monday.

I won’t be able to pick them up until mid April, so looks like we’re on hold till then.

[El Camexican]

Picked up the gaskets on Friday. Just installed one and checked the squish, .048”, can’t ask for anything more.

I need to shorten the cylinder studs about .030” and then the head can go on for the last time. After that all that remains is to figure out the ignition timing.

[6spdls1z28]

Getting anywhere with this?


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[El Camexican]

Getting anywhere with this?


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Just needs the electrical system installed, and the head buttoned down. From there it goes into the frame, but I am waiting on a custom made top mount steel tank before I proceed.

[6spdls1z28]

I got mine running just waiting for a couple little things before I ride it. Sounds way more like a yz now


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[El Camexican]

I got mine running just waiting for a couple little things before I ride it. Sounds way more like a yz now


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Awesome!!! Which transmission did you go with?

[6spdls1z28]

Awesome!!! Which transmission did you go with?

Ended up keeping the tri z trans in it. I’m excited to try it in a few days


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[6spdls1z28]

Ended up keeping the tri z trans in it. I’m excited to try it in a few days


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This is it. https://youtu.be/X-cZqB8OHIw


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[Red Rider]

This is it.Sounds good 6spd!

Hurry up El, you know you want to hear that coming from yours.

[6spdls1z28]

Sounds good 6spd!

Hurry up El, you know you want to hear that coming from yours.

Thanks red rider! When I get the last little items I’ll post another video


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[6spdls1z28]

Hey el, do you have the flywheel torque spec off hand? Some reason I’m having trouble finding it. Have it torqued to the yz spec right now.


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