Shift4

Hey there, I'm new to this sport and so far am having bad luck with my 150. My latest issue seems to be a big one and would appreciate any help.

First outing - runs goods

Second - will only go approx 30mph - checked compression - 118 all three cyl. Changed plugs - R6918C-9 removed/installed runs great again

Third - racing a guy on a seadoo at full throttle for 2 mins after 1 hour of 180's and fairly hard riding. Coming around the last bend I let off the throttle and the engine sounds distinctly more noisy (kind of low rattle/knock - my first thought was a spun bearing??) I idled 2 mins to shore and pulled the ski out of the water. Met a jet ski mechanic who quickly listened to the motor out of water and said it sounds OK and to put it back in the water to test, which I have yet to do.

I took a compression test again and found approx 118 psi all cylinders.

Started the engine again - seems like a rattle from the top end but I'm not sure as this the the 3rd week I have ever owned or been on a jet ski.

I'm quite able to pull the motor and rebuild if necessary but would like some advice in terms of how to test/check if it is necessary. Also is there a service manual available online for this machine?

Thanks in advance
Steve

Shift4

Turned out to be the bearings in the jet pump. Ran it again after the repair and it ran great for an hour. Now it will only go 30mph again??? Can it really need new plugs again?
Steve