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View Full Version : TRX 90 Big Bore Install - NEED HELP!



mrman5050
04-08-2009, 11:48 AM
I'm trying to install a 114cc big bore cylinder kit on my son's 2005 TRX90. I am re-using the stock cylinder head assembly.

My issue/question is with the air suction valve tube that mounts to the stock cylinder. The big bore cylinder does not have a port to accept this tube which is fine as it is easy enough to eliminate. HOWEVER, the stock cylinder head has a small port that runs from the exhaust port, through the cylinder head and into the cylinder (eventually exiting out the now-eliminated tube).

Since the big bore cylinder does not accomodate this tube, the top of the cylinder was not designed to specifically mate up with the bottom of the cylinder head to effectively block off the "exhaust" hole in the bottom of the head.

From what I can see, if I try to use this cylinder/head combination I will have two problems, 1) hot exhaust gases will be dumping directly on to the cylinder (bad) 2) I will have one heck of an exhaust leak (also bad).

My thought was to simply JB weld the hole in the cylinder head but there has got to be a better solution.

Not one of the websites selling Big Bore kits for the TRX90 says anything about not being able to use the stock cylinder head. I'm sure someone out there has experienced this problem. The "tech guy" at the website I piurchased this from (as well as a few others I tried) were unaware of this issue which makes me question dealers that sell items that they have no experience installing or testing.

HELP!!!

Thanks,
Marc

smokinwrench
04-08-2009, 01:19 PM
I went through this same exact thing with my boys 06 trx90 when installing a 114 kit. I don't remember exactly what I did to fix it. Let me look at some of my old threads about his 90 and see if I wrote anything about it. You might also try and get on exriders and see if anything is on there.

I just searched and didn't find anything on my old threads. I know I eliminated the blow by tube. As for the exhaust leak I don't remember what I done, I know I didn't use jb weld though. I would search exriders I'm sure there is info on there.