85 tri z with newer yz250 engine. What will it take?

[86tri-zrider]

Hey everybody, ive searched for what seems like weeks now for someone that has or knows something about how hard it would be to swap a newer yz 250 (2001+) engine into a tri z. Yes i know the 80s yz engine are direct bolt in but thats not what i want. If anyone has an idea of what all it would take to get a newer yz motor in the tri z chassis please let me know!

[86tri-zrider]

Does anyone have any ideas on this subject?, id like to hear any and all opinions on things ill run into with doing this. Ive found an 03 yz250 all complete running for $500 it needs a clutch pushrod. I plan on using the wiring harness, carb, and twist throttle assembly from the bike along with the engine. Hopefully will have the bike this weekend to start tearing into this project. Again any feedback is helpful thanks

[sledcrazyinCT]

Good luck with the swap....hope someone chimes in. Make sure you post pics of the build!

[onformula1]

I don't know why the guys are not chiming in, my best guess is you only have two posts, we don't have a idea of your skill set, you are in the new member section and are a newby...but, I am jumping in on what I would do, thoughts and ideas as always we me everything is IMHO.

I have built some nice Tri-Z's and some fast YZ's, but never a Tri-Z with a modern YZ engine and have never seen nor heard of one. That doesn't mean it can't be sweet.

Possible problem areas-

The YZ engine is a vertical cylinder design meaning the cylinder sets back and straight up so the head may interfere and the exhaust area on the cylinder is different and uses a different size diameter, the power valve may also interfere.

I know the engine is smaller in size so that's good, but it was also designed to have the pipe on the throttle side so a custom pipe will be needed no matter which side you decide to route it. Could a Tri-Z pipe be modified to work, yes anything is possible, but it will not run correctly and you will lose a lot of the power gained.

I would drop kick the stock fuel tank and get a jeswinehart top mounted tank (Excellent, talented forum member here) now you will have some room for the canted YZ intake manifold and larger 38mm carb, I would build a custom airbox that uses the YZ airbox boot. The Modern MX bikes are designed from the airbox to the tip of the silencer to work together, a pod type filter will lose power you are gaining from a modern engine. I would use larger upgraded Tri-Z or the YZ radiators to keep it cool a MX bike has the cooling advantage of a skinny front tire, huge shrouds and are designed to get air in, cool the radiators and also get the hot air out these bikes are even wind tunnel tested. You never see a radiator coolant recovery tank on a MX bike

Forget the forward kick starter, that will be gone, so cut fenders or a flip-up will be needed. They have no lighting coil without mods so forget the lights.

Using a 9-10 oz plus flywheel weight will make the engine more ridable in a trike and will have a bit less vibration.

Fabbed engine mounts will be needed and the swing arm pivot bolt will be larger, so a machined sleeve through the cases are needed, build a head stay as well.

A wider axle, plus 3" swing arm, modified shock and forks to at least be stiffer and have more rebound would be very helpful with all the added HP.

I would also run a modified the YZ silencer (The stock YZ silencers are very good) for more fun chop the can down to 7-8" and pack it very, very tight. I would not mess with trying to make a Tri-Z silencer work.

The shifter will need to be lengthened or replaced

That's where I would start, I am here to help if you have questions, now post some pics! :lol:

[86tri-zrider]

First off i want to thank you for all of the useful info and your opinions on the subject. Most of the "issues" that youve pointed out i have thought about but there are i few that i did not. You say the yz engine sits at more of a vertical than the triz, how much so? Is it a huge difference between the 2 or minor? As far as the engine mounts i had already planned on having to make them custom, by no means did i think it was just gonna set in and bolt right up! Although that would be nice, by question is on the rear engine/swingarm mount. Is the yz the same as the z? Other than the size bolt that will be needed will the rear yz mount slide into the opening in the swingarm? And then will the chain come close to lining up? That was the part that i was hoping would be close. As far as the other mounts im not worried they can easily be fabbed up.

[86tri-zrider]

223373 the chassis im starting with is an 85, after many years of neglect sitting in a buddys barnyard with the topend missing i finally talked him into parting with it. Being that the crankcase was left open to the weather i didnt have much to start with here which is what lead me to wanting to run the yz engine in the first place223374

[freewheeler]

A modern yz engine is in no way a bolt in to your tri-z.

[86tri-zrider]

A modern yz engine is in no way a bolt in to your tri-z.

Oh really? I thought it would fly right in and bolt itself down.

[onformula1]

Here are some pictures so you can see the vertical YZ engine in comparison. I am not saying it is a huge amount but when 1" on a Tecate KX500 means the difference between running a spark plug or not, it doesn't take much...LOL

Again I don't have both these engines in my shop, but modern engines are narrower, most of the time that includes between the swing arm which is good you will need spacers but that will allow you to offset the engine to align the sprockets.

Sit on a 1985 YZ for a half hour, then sit on a 2005 YZ it will feel like a tooth pick top to bottom. The frame is about the same thickness but the engine is narrower, which allows the designer to use a thin tank, air box, seat, ETC.

223390223391223392223393223394

[86tri-zrider]

Yes i deffinatly see the difference when looking at them side by side in the pics, one good thing though is the size of the triz's engine bay, theres quite a bit of room for deviation from the original engine design.
The bike that i will hopefully be picking up this weekend is an 03 that suposedly runs very well but needs a clutch pushrod, or at least thats what the seller says. How big of a project is that pushrod to replace? The seller says the end is sheared off? Is that a somewhat common occurence in the yz or does that sound fishy? The pushrod itself looking it up online sells for about 15 bucks but ive never had a clutch on a bike apart before and dont really know what to think of this issue.

[onformula1]

The replacement is not tough, but get yourself a shop manual, you will at least need the specs.

Always plan on anything a used bike seller says is sketchy, play it safe.

That issue happens, usually from the gearbox oil not being replaced often, or the wrong weight oil, or a improperly adjusted clutch lever.

[86tri-zrider]

Alright thanks for the input, ill let you know more in a few days and post some more pics

[Tri-Z 250]

It can be done but your trans for the YZ250 has mod options as well. No doubt a full mod Athena 285cc motor might be an option but think 5speed. 426YZf's gears will drop into your YZ 250 cases with the talents of a good shop. It's basically todays 250YZX out for 2016 off-road market

[3 Wheel Drive]

Hey everybody, ive searched for what seems like weeks now for someone that has or knows something about how hard it would be to swap a newer yz 250 (2001+) engine into a tri z. Yes i know the 80s yz engine are direct bolt in but thats not what i want. If anyone has an idea of what all it would take to get a newer yz motor in the tri z chassis please let me know!


The forums have been pretty slow for a while but there is a lot of guys here who've done similar projects on the Tri Z'z:

http://www.3wheelerworld.com/showthread.php/164217-tri-Z-transplant?highlight=Power+valve+tri

Try different Z searches there's lots of pics & info on this site.

[3 Wheel Drive]

If you decide not to go with a yz engine, Klemm Research offers a 350cc Tri Z kit. Raffa is the only one I know who has got one running but he does not post here anymore. There's vids on YouTube with his 350Z, I think the kit us north of 1k and requires case mods.

http://trikeracing.com/discussion/6/klemm-vintage-tri-z-350-raw-meat-2/p1


More yz specific info:

http://www.3wheelerworld.com/archive/index.php/t-7015.html
http://www.3wheelerworld.com/archive/index.php/t-58910.html

[86tri-zrider]

The forums have been pretty slow for a while but there is a lot of guys here who've done similar projects on the Tri Z'z:

http://www.3wheelerworld.com/showthread.php/164217-tri-Z-transplant?highlight=Power+valve+tri

Try different Z searches there's lots of pics & info on this site.

Yes, there is alot of projects on here that ive seen, but mostly all guys running the 83-87 yz engine or doing thepowervalve mod from the same engine, i cannot find anything anywhere on any site of anybody using a newer yz engine. Ive been a member on this site for 5+ years but have just never really posted anything untill now, ive spent alot of time on here just reading, and havnt ever seen it done.

[Red Rider]

Nor have I. If it's been done, whoever did it, kept it quiet. Someone needs to be the first, so why not you?

[onformula1]

I like this build a lot, I was talking to a few guys on this board including John Neary about this set-up and no one disliked it, it has been on my to do list for about 5 years.

This thing will be very fast, but if you want to go to a big bore you will be limited to 265cc or 295cc because on the power valve, Eric Gorr makes a great kit.

You can also go with a new cylinder and head from ESR that uses a different power valve set-up, they make a 325cc & 345cc kit.

Here are some links if you are interested-

http://www.eric-gorr.com/index.php/services/big-bore-250s

http://www.eddie-sanders-racing.com/product_p/yz250-325-big-bore-kit.htm

http://www.eddie-sanders-racing.com/product_p/yz250-345-big-bore-kit.htm

I would prefer to run the stock cylinder & head modified for a big bore even if it has less displacement.

[86tri-zrider]

If you decide not to go with a yz engine, Klemm Research offers a 350cc Tri Z kit. Raffa is the only one I know who has got one running but he does not post here anymore. There's vids on YouTube with his 350Z, I think the kit us north of 1k and requires case mods.

http://trikeracing.com/discussion/6/klemm-vintage-tri-z-350-raw-meat-2/p1


More yz specific info:

http://www.3wheelerworld.com/archive/index.php/t-7015.html
http://www.3wheelerworld.com/archive/index.php/t-58910.html

That is pretty interesting i hadnt seen that before. My only issue is i do not have any stock tri z engine parts to start with. All i had is the bottom end and sadly its all scrap do to the fact it sat outside for 20 years with the topend removed. So thats why ive come to wanting the newer yz engine. In my mind its the best option starting with more or less nothing. And at the end of the day ill have an engine that parts are more readily available for and also an engine that there is all sorts of aftermarket support for (cough,bigbore kits,cough,cough)

[onformula1]

Nor have I. If it's been done, whoever did it, kept it quiet. Someone needs to be the first, so why not you?

Listen to this guy, he has the badest 250r engine ever! (IMHO) Which sometimes moonlights as a CR250R :lol:

[jonolanracin]

I am in the process of putting an 01 yz250 in a triz and the only issue i found yet is that the engine will sit right in between swingarm fine but the front sprocket doesnt line up so im going to cut 3 16ths off swinger to slide engine over up then make a spacer

[86tri-zrider]

I am in the process of putting an 01 yz250 in a triz and the only issue i found yet is that the engine will sit right in between swingarm fine but the front sprocket doesnt line up so im going to cut 3 16ths off swinger to slide engine over up then make a spacer

So do you have a thread somewhere going on this build? Id like to see pics of it and whatnot. I figured some modification would be needed in that area, and whether the material came off the swinger or the engine i didnt know which would be better. Ive had a horrible time of just trying to pick up one of the 3 donor bikes ive found for this project, idk if its just dirtbike people or what lol but everytime i suggest me coming to look/ buy the things all three of these guys just like quit answering me for a day or two. I dont get it, if your selling something you should be trying to make yourself available to get rid of it, not the other way around. So as soon as i get my hands on an engine i will be starting the process of getting it mocked up in the frame so i can get the frame off to powdercoat afterwards. Im hoping to have this project completed or close too it by spring time

[jonolanracin]

I havnt started a thread im trying to finish the restoration on my 86 tecate and dont have time to post much but i am going to cut the swingarm to get it set ill be sure to send you a pic when i get to

[86tri-zrider]

223589223590
Well heres the donor bike, finally was able to pick one of the 3 i was looking at up today, its an 03 got the whole thing along with a load of parts and aftermarket stuff i will probly never use for 500 bucks. It needs a piston and rings, bottom end is solid. Just pulled it off the truck probly 3 hours ago and already got the motor out sitting on the floor next to it. Hopefully whenever i get back in town from work ill start to get it mocked up in the tri z frame.

[onformula1]

223589223590
Well heres the donor bike, finally was able to pick one of the 3 i was looking at up today, its an 03 got the whole thing along with a load of parts and aftermarket stuff i will probly never use for 500 bucks. It needs a piston and rings, bottom end is solid. Just pulled it off the truck probly 3 hours ago and already got the motor out sitting on the floor next to it. Hopefully whenever i get back in town from work ill start to get it mocked up in the tri z frame.

You got a great deal, the rest parted out will easily get you your investment back if you go down that road.

[86tri-zrider]

The yz motor and triz case side by side on the garage floor, first things noticed are that the front case mount on the yz is a little wider than the tri z mount. Shouldnt be too big of a deal though as the way the triz motor bolts up in the front it uses plates that bolt to the motor on one end and to the fram on the other, should be able to make a set of stepped plates so i can use the stock front mount. As for the rear mount it is the same width and slides in the swingarm, but as previously stated on this thread by another member the front sprocket doesnt quite fall inline where it needs to be. It isnt off by much though, im hoping maybe the distance can be acheived possibly by just shimming the sprockets somehow, if not the swingarm will have to be shaved. I havnt actually set the engine in the frame yet to see where the bottom mount will fall.

[86tri-zrider]

Set the motor in the frame yesterday and started figuring out what needs to be done, also made up the bottom mid mounts and welded in place. Not the prettiest right now but ill get them cleaned up and itll look almost factory under some powdercoat. heres a few pics

[86tri-zrider]

Some more pics of progress. I got the engine all bolted down, made some custom mounts for the front and used the stock ones along with them, so far it looks like the stock radiators and where they mount will work with no issues. With the design of the newer engine the cylinder stands up straighter and creates quite a bit more room between the engine and the radiators

[3 Wheel Drive]

The 3ww shop used to sell beefed up foot peg mounts for the tri z. This might be a good time to look into it before you paint your frame. Some pics of the install: http://www.3wheelerworld.com/album.php?albumid=2336&page=2

This is not quite the same as your build but it's a newer yz trike build: http://www.3wheelerworld.com/showthread.php/176459-Yz450-trike-conversion?highlight=Yz+450

[86tri-zrider]

The 3ww shop used to sell beefed up foot peg mounts for the tri z. This might be a good time to look into it before you paint your frame. Some pics of the install: http://www.3wheelerworld.com/album.php?albumid=2336&page=2

This is not quite the same as your build but it's a newer yz trike build: http://www.3wheelerworld.com/showthread.php/176459-Yz450-trike-conversion?highlight=Yz+450

Man that newer yz build is pretty sick, i hadnt come across that here yet, thanks for the link, i might have to look into trying something like that when i finish this one. But yes i agree id like to do the foot peg mounts also, but the shop doesnt sell them anymore that i could see, ive tryed to get in touch with raffa with no luck yet, as i heard he had been making them. I guess worse come to worse i could just make a set?

[karendse]

I. No this is an old thread but I'm in the middle of this same prodject and I was wondering what came of the sprocket issues was it able to be shined I don't yet have my engin so I'm just getting an idea anything else you came across that made it tough

[oldskool83]

Bottom end is the same just put it in. 83-87 motors use same bottom cases.

[RobbieGreene508]

Sounds like a fun bike

[tskow]

I'm in a similar situation with my 86 Tri-Z. Sat at my dad's house for 10+ years with the top end torn down thanks to a piston breaking. Let us know how the build goes. Maybe I'll try out the same thing if it works well.

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