Vintage Dirt Bike Q & A

I have been wanting to put new silencer on my bike for a couple of years. I finally decided that I didn't want to put a supertrapp on it, but it is the only aftermarket 2-stroke muffler I could find with the necessary 1-3/4" ID pipe on front that would go over the built-in mini silencer at the tip of the tailpipe on these bikes. So, here is what I ended up doing: I bought a universal FMF silencer with the 1-1/4" inch pipe (biggest universal they make). Found a 2" to 1-1/4" brass reducer at plumbing supply store. It's about 3-1/2" long. I cut four slots in the 2" part of that and painted it black. It slipped nicely over the tailpipe gasket and I used the stock clamp to tighten it on. Now the FMF silencer was too long to look right, so I took it apart and cut 4" off of it and 4" off the inner baffled tube and the packing. Put it back together, slipped it on and drilled a hole for the rear hangar. Looks pretty good to me and sounds and runs fantastic.

that looks very good.i did a mod like yours years ago with my 75 CR250M1.i used a automotive reducer on mine with a DG universal silencer.these bikes sound pretty cool with a modern silencer.

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(2) 1968 DT1 1970 RT1M,1970 DT1C 1971 RT1B Enduro 1974 MT250 1974 DT250A (2) 1975 DT400B 1974 DT100,1978 DT175
1975 CR250M1 1979 CR250R 1979 Kawasaki KZ400H1 Jesus is Lord!!

Mitchie, Nice tank!!!!!! Bike looks good!
I hope you kept all the lights, speedo etc. Glad to see your riding the thing!

Thanks MR. That's my aluminum 1976 CR tank that only had one small scratch in it (underneath the FMF sticker) I got for a song on da bay. Guy had it listed as painted fenders and said "oh yeah, I'll throw in this tank, too." Needless to say I bought two painted fenders I'll probably never use. I paid more for my '75 CR seat base than I did the tank/fenders!!
Too bad I can't make myself sell it to someone who won't abuse it like me.
I love my bike. It's my pony and my friend.

Dave: I guess there is nothing new under the sun. I originally tried to have a muffler shop make an adapter, but they made a giant heavy thing that I couldn't clamp on. I thought there must be some type of auto exhaust adapter that would work, but I couldn't find one. I lucked onto the current solution when I was looking for a new part for a home shower!! Whatever happened to the M1??

It would take more work, but could the end of the pipe be modified? The outer pipe is 1 3/4" the inner is about 1". Could you cut and grind the outer pipe away and then put a 1 1/4" pipe back on and then weld it back up? It would be nice to modify the end of the pipe so that you can use a rubber connector and clamps, maybe from a KDX 200 or some other popular bike. Anyone else think this would work?

You can perhaps modify the end of the pipe, but I wanted to keep it original. I ended up tossing the plumbing parts and using two short pieces of radiator hose. A smaller piece of hose over the front pipe of the muffler to make it the same OD as the end of the pipe and the second, bent piece of hose, to tie them nicely together. I initially worried about melting the hose, but after two years, have decided there is no reason to worry. Still like new. Lets me angle the muffler up and looks and works 10 times better.