brady89

Hi Everyone'

New to the forums here so bear with me

Just picked up a 1999 Yamaha GP1200 and after taking it out twice I now have a few issues with it.

Previous owner said it was rebuilt about 20hrs ago and had the following work:
Oversize piston, Piston Rings, port and polished, New Crank, Aftermarket intake grate, solas impeller. Also oil system taken out so running 50:1 premix. I also checked compression Compression and its 112,120,112

1st issue: When out of the water connected to a hose it revs to 7000rpm but in the water it wont go past 6000rpm

** I've spoken to my local jetski place and they say that is normal because of the load of the water but does this sound right as i've read about GP1200's reving to 7000+ rpm in the water? **

2nd Issue Stupid mistake of mine when I took it out the second time I left the water flush hose off and had it running in the water for 2mins and water was not shooting out and the ski took in alot of water and got very hot. Water covered the battery so was quite high in the ski! I got it back on the trailer and got all the water out, took the plugs out and no water in the cylinders, got it started again after a while but lost alot of performance (My mates stock Seadoo XP800 flew straight past me) performing as if its 2 cylinders. Also when I got the ski home and hooked it upto water to flush it, it started to free rev right to 6000rpm before I cut it off. (Thinking possible air leak?). Also I thought I should ad the battery volt light was flashing as the battery was very flat and I had to jump start it. (Just because i cranked it quite a bit but just wanted to mention incase this could affect spark/perfromance).

** I've checked each of the plugs is getting spark so it is running on all 3 cylinders, there is no water in the cylinders, I've comp tested is and getting same figures as 2 days earlier when I took it out (112,120,112). I cant see if it has an air leak somewhere but im guessing this is why its free reving. **

Not sure what else I should check at this stage..

Any help/comments more than appreciated just hoping to get this sorted asap!

Thanks Everyone!