Whistling Engine

[Dogcheese]

Hi everyone, I hope some one can help I've come across something with my Yamaha 50hp triple. When it is throttled up or down it emits a very brief and shrill 'PEEP'like a demented kettle, spitting through the prop exhaust. It's been hinted that it could be an air leak, if you've come across this before I'd be grateful for some info on the cause and remedy. Cheers.

[boats.net]

It's a lean pop, like a backfire in crankcase. It is caused by a lean condition, dirty carbs or air leak on intake. 99% of the time it's dirty carbs.