Vintage Dirt Bike Q & A

I have an old 78 CR250.... When I shift from neutral into gear it gives a big clunk sound and feel. What part of the transmission is wearing out and needs fixing? Or could it be multiple things?

Thanks alot!

It could be so many things it is really a guessing contest.

As long as the bike does not pop out of any gear under *HARD* acceleration and shifts properly the transmission would not be my first suspect. The clunk is often because your clutch is dragging a bit. Warped plates making partial contact, crud between the plates, wear on parts, wrong oil, that kind of stuff.

Even check the tension on the chain and get rid of any slack.

Rick

my friend even has a 2008 bike and when you shift from N to 1st it gives a little clunk and you can see the chain move. possibly it's just working as it should?

I haven't worked on a bike newer then the 90s<grin>, but I assume not much has changed.

A little bit of 'klunk' is OK, maybe even necessary for the transmission to work the way you want it to.

A bad clutch can have so much drag, the engine dies when you put it in gear or the bike jumps forward. Think of a warped friction plate as having a shape like a potato chip. It squashes flat under spring pressure with the clutch out but still warps out to make contact with the clutch in.

There's also the problem with notches wearing in the clutch basket. Instead of the plates separating, they get locked wear slots in the basket. I have only seen bad one of bikes that have been raced, but then I have seen them on every engine I know has been raced ~6 or so.

Rick

I have a 79. The clunk is mostly due to the clutch. As mentioned, thr basket may be notched. Very easy to check.

Good luck.

Dan