Motorcycle Repair: sl70 problems, hash marks, light hook

Question
hi i have 1971 honda sl70that falls on its face when you give it gas it idles perfect.if you gradually give it gas itwill rev up ok but if you cram it it dies im wondering ifspark advance is worn and not doing its jobit has new points and condenser and timing is ok and so is the valve clearance whats next

Answer
Brian, try applying a little choke when you open the throttle.  If it improves the problem, it a carb problem.  If it doesn't help, it could be the timing advance unit.  You can check the advance unit easlily enough if you have a timing light.  Hook up the light and start the engine.  It should be firing at the "F" mark on the flywheel.  WHen you rev the engine up the timing should advance to between the two hash marks.  If it advances, that's not the problem. It's more likely a carb problem and you need to clean and adjust the carb.

Regards
Rich