1983 250 exhaust o-rings and aftermarket silencers ?

[professortp]

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

[KDXGarage]

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.

[professortp]

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 ?

[KDXGarage]

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).

[KDXGarage]

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.