1999 yamaha xl limted 1200

[waverunners]

first off..sorry for the long post :-), i'm new to jet ski's..i road one last year..it also was a yamaha..but it was a 4-stroke....i work on 3 and 4 wheelers as a hobby...soo..i'm very well mechanicley inclined...on this ski i have now..i already knew it had a dead cylinder..# 3 the pto...sure enough..after tearing the motor down..and getting to the crank case..the # 3 cylinder had a busted hole through the top half of the crank case..piston,cylinder and raves are shot..the guy claimed it ran on 2 cylinders...i never cranked it up..fearing it would do more damage, my question is..what causes the cylinder to go bad ??..i read a few post on here..that yamaha had issues with oil lines coming off..but..as i took the motor apart..all the oil lines seemed to be hooked up..soo..when i get my new parts in..and start to put it back together..what should i look for ?..i'm thinking maybe the carbs ran too lean ?.oil pump shouldn't be bad i would think..or more than one cylinder would of got fried . any help on this would be great..thanks in advance.

[JRock]

Re: 1999 yamaha xl limted 1200

I am in a similar situation... Just bought a 2001 LS2000 and the pto side cylinder in the starboard engine is wasted. I'm already on my way with a reputable shop in my area boring the cylinder and they picked up a new SBT piston for me. My question is the same... I would really like to know the cause of the problem. The damage was done before I bought the boat so I don't know what was going on when it happened. I have already rebuilt the carbs and did intake gaskets so my first thoughts are that the carb for that cylinder was running lean.

However, I am noticing that this seems to be a frequent problem with the pto side cylinder on this motor. Anyone have any input for the cause? The boat is otherwise super clean and was well taken care of so it's not like it has been run hard and put away wet its whole life.

[Technical Support]

Re: 1999 yamaha xl limted 1200

Most of the time its a rear crank seal that leaks and runs the pto cylinder lean. On the powervalved motor it could be the catalytic converter clogging up that may causes it to burn the piston. Also the correct pop-off on all 1200 and pv 1200 Yamaha engines is critical if they are not set high enough you will have problems. 55-60 on non pv and 60-75 on pv models.