1978 KZ400

Hello, I have a 1978 KZ400. At light accel the engine pops and misses out. If I give it more throttle then it clears up and runs Great. If i go to Full throttle from take off it runs fine. Sometimes it pops out of carbs at idle. The engine is rebuilt with LESS THEN 50MILES. Any Help would be nice

try spraying wd40 on the carb boots when its idling to check for vacuum leaks

Hi Jonny, welcome to the site. Terry is right, the carb holders may not be completely sealed. You may also have reused the exhaust gaskets and this may be causing the popping... ANY air in the combustion chamber from a leak will cause the popping. Could also be a missing vacuum cap or vacuum hose leak from the carbs, etc.

Hello, Well thanks for all the information. I will try that tonight and keep yall posted about what I find. Thanks Again.

Hello, Well I sprayed some carb cleaner on the intake boots and around were the boot meets the head. And when I did this the engine died out. Do any of yall know were I can purchase these boots new at a good price? Thanks, Jonathan

I just put some new intake boots on my motorcycle. And they solved the problem of popping at light acceleration. But I have to have the motor all the way RETARDED, or it will not idle, and will pop out of the carbs. I have a performance ignition system... with One Automotive Coil for each cyl. with a Automotive Ballast Resistor and a New Automotive Condensor. Do any of yall have any idea how to fix this problem.Even with the it all the way Retarded it still doesnt run like it should.