80 Excell V Exhaust backfire

[bgkid2966]

I have a problem with an exhaust backfire on my 80 Excell V 540 fan engine. It runs pretty good but does not have the power it used to. When it backfires it will die sometimes and will restart easily with the choke on. It makes me think it is lean, but I am not sure. I have cleaned the carb twice and no change. I also have checked for vacuum leaks all over. The sled idles and revs ok, then backfires.

Any help would be appreciated.
Thanks, Geno

 

[bgkid2966]

I pulled the plugs and the left plug was tan and the right plug was black. This engine has one carb. So, now I am really confused. This problem is driving me nuts.


HELP!!


Thanks, Geno

 

[Throttle Junkie35]

Intresting, I have an SRV with the same issues. I was thinking lean also.

 

[Yamaha Nutz]

just went through this on my SS440 racer ..........but no back fire ........most likely a bad pulse line or crank seals ............the SS 440 and 540 fan motors eat crank seals for what ever reason and 90% of the time that is the reason for burn down on these motors .............also a bad base gasket could be a issue ............