1998 Yamaha Waverunner XL 1200 Rebuild

[stevenvalerie]

I just bought a non-running Waverunner. I bought it without being able to check compression and was told that the only thing that was wrong with it was the jet pump.

After tearing into it, I first discovered that the starter was toast. I opened the starter and it was so rusted I could barely pull it apart. Therefore, I still cannot check compression. However, I was able to turn the shaft coupling by hand and the engine turns easy enough. I inserted my compression gauge into each spark plug hole. I found 2 of the cylinders very hard to turn due to compression but 1 cylinder is not compressing and you can hear air leak somewhere during the compression stroke. So I assume I have little to no compression on that cylinder. I also assume that the air could only be leaking through the rings. Would the damage have to be bad for air to leak when turning by hand? Or will worn rings do that?

I do not want to put a lot of money into this project and didn't invest much when I bought it for this very reason. I would be able to rebuild this motor easily but everything seems so expensive. I am trying to figure out what the minimum is that I could get away with replacing. I have not removed the head yet to see the extent of the problem. If I find that the cylinder is clean and rings are the problem, can I get away with a top-end rebuild? How important is it to inspect the crankcase and crank in this situation? Also, how important is a pressure test in this situation? One reason I have not removed the head was so that I could do a pressure test if need be. Are the crank bearings and seals okay even though its 15 years old?

My idea would be to 1: pressure test the crank case, if it passes and the crank turns smoothly then assume all is well with crank case 2: remove heads and cylinders, replace rings, hone, reassemble with new gaskets. 3: Clean and rebuild carbs.

Am I wasting my time? I would hate to put a few hundred dollars in this and it seize after a couple of hours running.

 

[jbetzelb]

Re: 1998 Yamaha Waverunner XL 1200 Rebuild

Compression on two but not on the third could likely be more then rings. Scored cylinder or a hole burned in a piston. Pulling the head will likely tell you how far you have to get into it.

 

[sixfigures]

Re: 1998 Yamaha Waverunner XL 1200 Rebuild

try to view the top of the piston, if it is silver or pitted you have some issues , however if it is brown you may just have some stuck rings , here is a very inexpensive way to see if your rings are just hung from sitting, bring the piston close to top maybe 1 inch below top dead center, and pour some automatic transmission fluid in and let it sit for several days. this can loosen the rings. also check for end play of each piston , simply rotate each piston past top dead center while viewing it through the plug hole after you see the piston start to go downward, stop and push on the top of the piston with a screwdriver, listen and feel for a clunk. if there is a clunk you probably have worn or rusted rod bearings or a bad wrist pin / bearings there.

 

[Bamaman1]

Re: 1998 Yamaha Waverunner XL 1200 Rebuild

I don't know your problem, but as above you should do some disassembly to see if the problem is evident.

If you need parts or a motor rebuild, there is a large PWC junkyard NE of the Birmingham Airport. Brian Dunnavant used to race Yamaha 2 strokes, and he's a very knowledgeable person with those engines.

www.dunnavants.com/‎

 

[stevenvalerie]

Re: 1998 Yamaha Waverunner XL 1200 Rebuild

Thanks so much for the replies. I have good news. I removed the head and the cylinder in suspect looks perfect. It appears I have stuck rings. I can put some oil in the cylinder, then rotate the crank by hand. On the down stroke, an air bubble shoots up from between the cylinder wall and piston. Does this sound like stuck rings? I don't remember every dealing with stuck rings before. So far I have not been able to unstick them and am ready to remove the cylinders. My next question is can I remove the cylinders and clean/unstick the rings. Then use those same rings without honing? Or can I hone and use the same rings? Or do I need to just purchase new rings and hone? I would buy new rings with out question but they are like $45 a set! I think I can find some aftermarket's a little cheaper.

Also, the piston does have a little play in the cylinder but I assume its because the ring are stuck.

Thanks for all the adv