Tri-Z Engines

[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.

[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.

[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.

[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.











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.











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

[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.





Sprock SS impeller



PV governor assembly





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....





...and on with the new.





Thank you Yeagerb!