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Hello everyone! I'm brand new to the group and hoping someone can give me info on correct installation of what appears to be a rubber like o-ring at the cylinder exhaust outlet/expansion chamber inlet on my 83, 250. Also, what would be a good after market exhaust silencer, and where can I find one ? Thanks ! Professortp

professortp wrote: 10:23 am Mar 03 2020 Hello everyone! I'm brand new to the group and hoping someone can give me info on correct installation of what appears to be a rubber like o-ring at the cylinder exhaust outlet/expansion chamber inlet on my 83, 250. Also, what would be a good after market exhaust silencer, and where can I find one ? Thanks ! Professortp

Welcome to kdxrider.net. Thanks for joining and participating.

I do not know what size pipe is on your bike. This might be a possible option:

https://www.fmfracing.com/Product/Produ ... earchText=

As to the o-ring (reference number 92055), here's the parts fiche picture. There is a copper gasket (11009 reference number) between the steel pipe and aluminum cylinder to keep it from gouging the material. The reference number is not the part number.

Thanks for the quick reply. In reqards to pipe size I haven't measured it, but it's the stock exhaust whatever size that may be. My question is about the installation of the rubber-like o ring. The new o ring that came in the top end gasket set didn't fit securely in the groove machined into the exhaust port even after I stretched it until I was afraid of breaking it. Is that how it's supposed to fit ?

Check the parts diagram here:

It says 55 mm diameter o-ring. What size is yours? (besides too small, ha ha :-) )

Is there not a groove in the pipe end?

Sorry to not be of much help on this. I have never seen a 1983 KDX250 (in person).

After looking on eBay at a pipe and cylinder, I am guessing the o-ring goes on the outside of the pipe, between the pipe and cylinder. The groove in the cylinder is where the outermost surface of the o-ring would rest. I would throw some silicone RTV on there besides just one o-ring.

A single o-ring is not the world's best sealing system. Later KDX's usually have the copper crush gasket and two o-rings.

I know this is an old post but I wanted to chime in anyway amd say that I boughtnew gaskets for my exhaust pipe and the only thing that actually went in there amd it was tricky to get it to stay in there while putting the pipe back into place was the brass ring. There were two other rubber looking things but they wouldn't seem to stay anywhere either. There is a ring on the pipe but once I started to push the pipe back in the gasket would roll out of it. I gave up and just left the brass ring in place lol. It's an 800 dollar bike amd I have clutch issues that are more important to me so I can ride the thing without it winding out and not moving anywhere very fast lmao