1997 Yamaha 200 TXRV carb - blown powerhead

[Captn Dave]

I blew the powerhead on a 1997 Yamaha 200 TXRV carbed engine. There's a hole in the lower right piston (as looking at the heads) that is typical of a lean failure.

I'm going to rebuild it but of course want to correct what caused the lean condition.
I pull the powerhead and notice that the filter bowl on the side of the engine is loose. I'm assuming this caused the engine to lean out.

Am I'm correct in this assumption?

 

[GrayBlue]

Re: 1997 Yamaha 200 TXRV carb - blown powerhead

how loose? was fuel coming out of it when you pressed the bulb kind of loose? too much air will lean it out for sure. Was the hole created by detination or a bearing? Detenation could be timing or too much carbon on that piston causing hot spots. I would test everything after you rebuild...ignition, fuel, etc.