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I have an '81 CB 750. Last week it suddenly lost alot of power. After looking into it I figured out the 2 & 3 don't seem to be firing as the pipes on those 2 never get hot.

I tried switching the coils around and got the same thing. I switched the spark units around too..same thing. New plugs made no difference either. Mechanical?

Any help is greatly appreciated as usual!

Thanks in advance!!!

Check the compression on those cylinders. The head gasket may have burned between the cylinders.

check for spark on those coils with the plugs out, if no spark, you may have an open somewhere.

O.K. I checked the spark and there is one...a little one. So I'll have to do that compression test ( gonna need the manual for that one ). Any other thoughts? Bugger is I really don't want to put much more into this bike as I'm buying a new one in the spring but I'd like to ride through the fall!