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

I would post the same pose here http://www.3wheelerworldforums.com/