Tri z domes, and porting,help advise .PLEASE

[iwallace]

Finally tracked some domes down.
Few questions for ya.
Going for rebore and new piston .What make piston works better( dome of piston if there is any differences )
Going to be ported with extra boost. Does anyone on here know somewhere in uk that knows what there doing .
Has anyone got any pics of where to weld to save it from cracking
Thanks ian

[3Z with Fangs!]

Ian, I don't know that it has to be welded, the biggest issue is making sure mounts are tight so the engine can't move. That's what causes the cracks. I have pics of mine I'll try to post later.

[El Camexican]

I’m not convinced the weld is needed on every cylinder, but not all of them were created equally, so it’s a good idea to have it done.

Just look at the left side of the cylinder and you’ll see that it has additional material next to the boost port, that’s what you want to duplicate on the right hand side.

As far as I know all the piston domes out there have the same shape. Most people will tell you to stick with a Wiseco piston.

For porting you’ll want to avoid anyone claiming they have some radical method of getting 60 hp out of your engine. There’s plenty to be gained from that engine with the boost port, some cleanup and matching of the transfers and raising the exhaust port a bit.

[3Z with Fangs!]

255412255413 mine that I did

[christph]

I just replaced my Tri-Z piston with a YZ 250 piston (83-87). They are basically identical except the YZ has a taller dome, whereas the Tri-Z is almost flat. If you are looking to bump up your compression a bit it's a good option. It will change your squish tolerance so you want to pay attention to that. When I first put the YZ piston in I had a problem with detonation because it reduced my squish to about .030 (I run 50/50 race and pump). I spaced it out to .042 with a copper base gasket and it fixed the problem. By the way, I found a great source for copper base gaskets for the Z. Copper Gaskets Unlimited makes gaskets in a wide variety of thicknesses so it makes it easier to hit your target squish tolerance. Here's a link to their website and a picture of their gasket.

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https://coppergaskets.us/

[El Camexican]

I just replaced my Tri-Z piston with a YZ 250 piston (83-87). They are basically identical except the YZ has a taller dome, whereas the Tri-Z is almost flat. If you are looking to bump up your compression a bit it's a good option. It will change your squish tolerance so you want to pay attention to that. When I first put the YZ piston in I had a problem with detonation because it reduced my squish to about .030 (I run 50/50 race and pump). I spaced it out to .042 with a copper base gasket and it fixed the problem. By the way, I found a great source for copper base gaskets for the Z. Copper Gaskets Unlimited makes gaskets in a wide variety of thicknesses so it makes it easier to hit your target squish tolerance. Here's a link to their website and a picture of their gasket.

255428

https://coppergaskets.us/

Great to know on those gaskets, I need to check that out. I have a YZ piston that I’m going to compare to the Tri-Z piston, the only difference I remember is that there are windows in the three wheeler piston and none in the motorcycle piston.

[christph]

Great to know on those gaskets, I need to check that out. I have a YZ piston that I’m going to compare to the Tri-Z piston, the only difference I remember is that there are windows in the three wheeler piston and none in the motorcycle piston.

Yeah, the windows are different. Well, technically the YZ doesn't have windows. It has an arch-shaped cut out on the skirt. And the dome is definitely taller.

[El Camexican]

Ok, so I pulled them out and put them side by side. The YZ piston is about 1/2 mm taller, but it also has more meat on the dome. Definitely going to yield higher cylinder pressure.

It seems the YZ has it’s own piston and the Tri Z and IT shared one.

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[3Z with Fangs!]

So the YZ Piston could be used with no issue to bump compression with basically no ill side effect?

[El Camexican]

So the YZ Piston could be used with no issue to bump compression with basically no ill side effect?

I’ve read yes and no and a bunch of other theories about which is best and why. Search this site and you’ll find some.

Myself I would think the difference might have something to do with the larger intake of the YZ. I guess you could put windows in the YZ piston too.

Maybe the single boyseen port on the Tri-Z necessitated the windows rather than the cutout of the YZ piston? Someone smarter than me must know, like maybe a Yamaha engineer :lol:

Does anyone have an IT cylinder? Guessing it’s a hybrid of the YZ and Tri-Z cylinders.

[iwallace]

I was thinking the yz piston and head,if i cant get the domes, also they do a 70mm piston with a pretty flat dome,needs a resleev though.Im only looking for different options until i get the lump out.

[3Z with Fangs!]

Water outlets on the YZ head are configured differently. I guess you can fanagle something but the hoses won't be direct line with the TRI-Z head.

[El Camexican]

I belive you need the YZ cylinder to use the YZ head. That implies a power valve, rad hoses and having the carb in a different place. The last good thread I saw on this was Neverlift's build if you want to look it up.

[El Camexican]

255412255413 mine that I did

Are you using that cylinder? It looks like your sleeve is broken.

[3Z with Fangs!]

Are you using that cylinder? It looks like your sleeve is broken. no, I got another jug and started over. This cylinder awaits a bigger sleeve.

[NeverLift]

I run a Sprock tri-z head on my 85YZ cylinder. Coolant hoses all fit perfect. I ordered YZ domes for the head and the one labeled "pump gas" has 230PSI I don't remember what the squish was but I run 110 with no issues. I've never even tried the "race gas" dome. I am using a YZ piston and matched the arch on the skirt to the cylinder and added the 2nd boost port. I've added the 2nd boost port to 3 different cylinders with no welding and never had an issue.

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