sportster lt problem

[robin1971]

Got a question about my sporter Lt twin720s. Went out on the lake boat ran awesome for 2 minutes, then I noticed my left hand motor started losing RPM's. So I turned off my good motor, and left the other running but noticed it was running rough, popping, and wouldn't rev up, till it stalled out. Went to shore changed the plugs on that engine, fired it back up and it ran beautifully for about 2-3 minutes again, then same thing running rough, revs and was also smoking kind of a white/blue smoke. The boat had been running fine all summer long till this last trip. So, anyone have any ideas where a good place to start would be?

 

[Steelmesh]

Compression check. Replace spark plug caps (ngk). Air leak / loose parts mechanic check / misadjusted or bad wire cables at carb. Fuel systems and hose check, filter change, carb rebuilds. Electrical box connector or coil corrosion.

 

[Seadoodoc]

We have one in the shop for same symptoms and did a complete run-through found the spark plug boot was split arcing crossed head. Driver side prop is completely bashed up and no wear ring

 

[robin1971]

thanks for the info I will definetly try that first