Vintage Dirt Bike Q & A

I picked up another 83 CR480 and it started just fine but ran rough. I replaced the carb with one I intend to use on the CR I'm rebuilding and it still runs rough.

It will idle without the choke on but it seems to kind of sputter when I roll the thottle on. It did exactly the same thing with the other carb. Both carbs have stock jetting and I adjusted the air screw 1 1/2 turns out.

Any suggestions on what I might look at next to resolve the problem?

Thanks for the help,

Jim

mine had bad crank seals is it smoking more than normal or can you smell gear oil in the exh.

Three obvious variables....
1. Jetting. Stock CR480R jetting is rich. You need 152-ish main and a 70 pilot. Plus raise the clip on the needle.
2. The carb is worn. Eliminated if it is new and/or works fine on another bike. (I think you are OK on this one.)
3. Primary drive crank seal is worn. Transmission oil will make exhaust smoke.

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Michael Stiles
1979 Honda CR250R Elsinore | 2006 Husqvarna SM510R | 2007 Service Honda CR500R-AF