Vintage Dirt Bike Q & A

Hey all. New to this site and I am so glad there are resources like this out there for the old bikes. I found a mr250 in a shed and I am going to go through it to get it running. It may have ran when I got it but I was pretty sure that it would need a little loving. I pulled the cylinder head off and the piston and rings were just barely in spec. so I cleaned up some carbon build up and ordered somr gaskets from Re-MX and put it back together. Why are there 8 cylinder head studs but only 5 in use? I see some gaskets out there that cover up 3 of the holes and some that have all 8. I had to replace the contact breaker and this old bike had no lights or speedo so I cut out a bunch of wires. Can the stator "go bad"? I cleaned it up and did have to solder one wire. I see where you can test it so I'll chek that out. How about the mag? This one was fairly rusty but with a light Dremel and a brass brush I was able to get it pretty clean. Overall I think this bike is in good shape for its age. I will let you know as things progress. Yesterday my hephew and I took the carb apart and its soaking so we will try to put it back together this weekend. Looks like I will need the rubber boot from the carb to the intake port. Any ideas where to find one? Also how many of these bikes were made. Does it go by serial number? This bike has a single digit number (100000X) so does this mean it was early production? Just a bunch of random questions but thanks for your knowledge and patience.

It was a single year bike as far as I know and I think the last few numbers are going to be your production number ie 100000951 I think means your bike was number 951 to be made that year. You shoulda left the harness whole even if you didnt want lights right now you may later and its not gonna be easy now.

Thanks woosh
I think I had too few 0's. I mean that the serial # is 10000000X. I suppose that means it was early prod. How many did they make? Just curious. Me and my nephew put the carb back together and I discovered that the air jet(?) in the throat on the intake side of the carb is missing. I also was not able to get the jet out of the inside of the throat on the other side of the carb, so I guess I have some work still to go. I know little about these carbs so I was just going to put everything back the way I found it and go from there. Any suggestions for a carb that will be used @ 4-6000 ft? Thanks I will let you know how things are going.

Carbs are probably the most important component in a smooth, responsive motorcycle. The cable between the two carbs is the idle sync. The sync adjustment is done at the front carb; there is a threaded adjuster with a lock-nut on this cable. The idle sync, once set correctly, seems to stay in sync for a long time.

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