2001 XL800 Waverunner - Engine died at full throttle

[Elliomcmh]

Hi,
I have a 2001 XL800 with 118 hours on it. When I bought it a few months ago, it had 108 hours on it and had 120psi compression on both cylinders.

I was riding it this morning at full throttle and all of a sudden then engine died. It would start back but sounded very strange and had no power, so a boat towed me back to the marina.

I towed it home and pulled both plugs and checked the compression. The spark plug on the front cylinder looked fine and the compression was 120 psi. The electrode was bent on the rear spark plug and the compression was only 60psi.

I have worked on plenty of boats just not many waverunners.

Any ideas? Thanks!!!

 

[alldodge]

The electrode was bent on the rear spark plug and the compression was only 60psi.

Not a Yam guy but did find out its a 2 stroker. Being the plug was bent, my first thought is something came loose and came between the piston and the plug, like needle bearings in the connecting rod, or something else in the motor.

Having only 60 psi, I would pull the head to find out if it looks dimpled. If this is the case then the bearings are coming apart and being drawn into the combustion chamber

 

[Elliomcmh]

Yes it's a two stroke, should have added that to the post. I'm going to pull the head Monday and survey the damage.