1982 Yamaha Maxim 650

Hi, my bike just spins but won’t fire. new plugs,getting good fire and comp.
cleaned carbs twice and still just spins.can you help? -terry

Hi Terry,

It could be many different things. Are your spark plugs wet when you pull them out? Just because the carbs are ‘clean’ doesn’t mean the fuel is getting to the cylinders. You could have the floats set too low, or poor fuel flow from the petcock.

Have you sprayed fluid directly into the airbox while cranking to double check the strength of your fire?

What compression readings are you getting?

Air leaks on the intake will very often cause this problem. Are your manifold boots in good shape and sealing well?

Have you checked the valve clearances? Even if they’re out it should still sputter, but definitely worth taking care of so you know for sure they aren’t the issue.

Evan Fell

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