Motorcycle Repair: 1983 XL250r

Question
I bought a 83 xl250r for harescrambles but am having problems with it. Bike has a bad miss when you apply throttle. I have installed a new carb, new coil, wire and plug boot as well as the plug and I still have this problem. I am very confused and don't know what else to try. Any help you shed on my problem I would be grateful.

Answer
Jimmy, did your "new carb" match the one that came on the bike or was it an aftermarket carburetor that fits the bike? Does it have a stock cam?

If the exhaust has been changed and/or the intake system altered from the factory installed parts, then you can expect to have to rejet the carburetor and/or change the needle clip position to get it to perform properly.

This assumes that you have good compression, no manifold leaks and a good piston/ring seal in the cylinder.

Some carbs have an accelerator pump to help part throttle flat spots. If yours doesn't then I would get a batch of main jets and go up one size at a time to see how it responds. Once you get it to pull full-throttle, then you can fine-tune the mid-range by moving the needle up and down using the clip positions.

Bill Silver