HELP! Tri- Z questions.

[jfaulkner02]

Ok, I recieved this 85 1/2 Z in a trade a while back. Been thinking about finally puting some work into it. Its basically complete with engine. Im pretty new with working on 2 strokes. Here is the tricky part.....When I got the bike the topend was off of the engine and I was told that it had a new piston, rings, etc. These parts do look new and seem to be in good shape. Here is why I have ?'s. With having the new piston and such you can tell that its been up the cylinder atleast once. My question is.....if it has new top end and appears that it has been reassembled, cranked, then disassembled......why was it taken apart? I have not just thrown it back together and gave her a kick due to this reason.....dont want to screw it up. Any info would be great...thanks.

[yamaha_ripper98]

typical reason for this is because alot of the cheap gasket kits have a very thin cylinder base gasket and when you fire for the first time it will leak and often this goes undetected until the first start had this problem with my first 85 tri-z engine build... you can tell by the crosshatches in the cylinder if the engine has been ran much since the last rebuild if its shiny its not as fresh if its real fresh you will see 1000's of vertical crosshatches on the cylinder wall crossing one another at about a 30 degree angle this is so the rings will seet good with the cylinder beause rings really do all the work the piston just mostly takes up space for compression and goes for one wild ride

[jfaulkner02]

Ok, yamaha_ripper98, basically i need to check the cross hatches? I just want to make sure i dont mess anything up when i go to fire it.

[El Camexican]

Measure everything up regardless of visual condition. Bore, piston, rings etc. Buy new gaskets and put it togeter. Ripper, which gaskets do you NOT recomend?

[zzmegad]

I'd go for the cometic top end gasket set... Their head gasket is a little more forgiving than the all metal ones. Iv'e always used vesrah with no problems, but their head gasket is all metal and doesn't work as well if your surfaces aren't flat.

http://www.3wheelerworld.com/showthread.php?59145-Tri-z-blowing-coolant-out-overflow...

http://www.3wheelerworld.com/showthread.php?66451-proper-install-of-a-tri-z-head-gasket-for-chris

[jfaulkner02]

Ok, so make sure the measurement for the rings, piston, and bore are correct then new gaskets to reassemble? Thanks everyone.

[El Camexican]

Dude, I have seen guys pull down bike engines with less than 5,000 miles because they "heard" something and then ended up selling the bike as a basket case years later because they had Humpty Humpty syndrome and could not put it back together again. I also bought a rebuild Chevy 350 from a buddy who said I was nuts to tear it down before putting in my truck as he'd barely run it. Turns out he had the wrong bearings in it! The crank was cut .020" and he put .010" bearings in it! Point is you may have lucked out and picked up something in perfect condition that only needs a little TLC, or you could have something that was torn down for a real problem like a blown crank seal, or a knocking rod. It's up to you if you are willing to put it back together and kick it over to find out, or if you want to tear it all the way down and be SURE its all good, but even if you go the easy route I advise you to check whatever can be checked and trust NO ONE! That said do make sure your rod is not loose, that there are no signs of leakage around the crank seals and that the cir-clips you are going to possibly reuse have not been damaged, etc.

[jfaulkner02]

Ok, will do. I have checked the gears, crank, etc. Everything seems good. It does help some that the Z looks as if its been taken care of pretty good seeing that everything is intact and good shape. After checking everything REAL good i guess ill throw it together and give it a kick or two. Anyone know of a downloadable manual?

[yamaha_ripper98]

versah is the one that i had trouble with everything was good exept for the base gasket in the full motor kit that i had got from ebay.. it could have just been a bad gasket in my kit tho im not sure i just know that i got a cometic my second time around for the 86 z when i had to replace the tranny in it

[jfaulkner02]

Ill have to get the engine to the house so i can scan it real good soon. Ill maybe get some pics.

[tri-Z ripper]

Use Yamaha OEM or Athena Gaskets work great as well. Check all tolerances especially on connecting rod and wrist pin!

[jfaulkner02]

Great! Thanks fellas.