Vintage Dirt Bike Q & A

Hi Honda guys
I need your knowledge. I restore Kawasakis and I just bought two 1978 cr125s. So Im new to these bikes. I want to know the difference between the 73-78 down pipes. They look the same but are they different? If so, what years of pipes will work on other years. Also the is there any difference between the heads of a 73-78 cr 125? Thanks for the great page and your help.

The 1973-74 CR125 cyclinder is the same. The 1975 CR125 cyclinder changed adding a boost port in the rear of the cyclinder (actually a better cyclinder) also known as the GP cyclinder. The 74-75 cyclinder heads are the same size & interchangable. The 1976-78 CR 125's are the same but wider than the 74-75 with more fins. The exhaust flange on the 76-78 is larger but will bolt right up to the 74-75 cyclinder allowing you to run the 76-78 pipe on your 74-75 cyclinders. The 76-78 cyclinder also has the boost port in the rear. I understand that the 74-75 cyclinder will fit on the 76-78 bottom end... but not vice versa!!

Hope this helps.

The cylinders and heads were wider on the post 1975 models
with more more fins on the heads. 1974, 75 and 76 cylinders were all different but interchangeable with the lower end if you had the correct corresponding cylinder head. I think the heads remained unchanged from 76-78.

I think for the most part all of those are interchangeable (main pipe); the newly designed Elsinore (23" front wheel) came out in 1979 I believe. The 74 Elsinore pipe had the long stinger silencer at the end which I believe were gone by the 1975 model. I have a 1976 Elsinore pipe on my 74 model (also a '74 cylinder)which fits OK, but it doesn't have the fat silencer on the end. Everyone I know took it
off of the '76 model back then anyway, because it choked
the bike.
I have an entire original exhaust for the 74 model, but it
is dented and has some corrosion.
Have you restored any KX-125's (1974-76)? I have a 74
which is a little thrashed (not too bad though) and would
like to restore it one of these days.

Hi Carl
Thanks for the info. I mostly restore the 78 kx125 a4. I just started a site but its not finnished yet but its http://www.vmxracer.com. I raced one of those early KXs like yours when I was 14. I wish I could find one. Want to trade yours? Make sure you check out http://www.nightmareracing.com This is the best kX site out there. If you scroll down the bike with # 4 on it is mine. Thanks vmxracer