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Discussion Starter #1 (Edited)
Hello everyone!

Well i have an opportunity to purchase and XL800 from a friend of mine. It has problem though... He says that one of the cylinders has very low compression, the numbers he gave where somewhere around 145 for one and 45 for the other.

It did start and idle a bit rough, with clouds of thick white smoke coming out of the exhaust. We did start it on the trailer without the garden house, just so i could see that it does in fact start and idle. We only ran it for about 15 - 20 seconds no revs.

He is willing to let me have for under one grand, which to me sounds like a decent deal. I am a decent mechanic and have rebuild my Jeep's straight 6 so tearing apart the wave runner's engine doesn't really scare me.

Wondering if anyone can help me shed some light on what the possible cause is and general idea of cost for parts. I am assuming that the piston rings are gone on the bad cylinder but i have no idea on the white smoke.

What do you guys think?
Thanks in advance for any help and info!
James
 

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Most common cause would be an oil line coming loose and resulting in a fried piston/cylinder. I'm pretty sure the XL800 has the power valve system, and that is another possible point of failure that would ruin a piston/cylinder, since on the original design it was possible for a power valve to drop into a cylinder and cause damage. In either case you would want to fix the power valves with clips if that hasn't already been done while you have things apart. Another consideration would be to convert the engine to run on pre-mix and eliminate the oil injector system, which is a common failure point. There are other possible causes for a piston/cylinder failure (lean run from bad carb., etc.). You really won't know until you get it apart.

There are different ways to go with the rebuild. If there is not too much damage, getting the cylinder re-plated (Nikasil), and a new piston usually gives you the best performance. You can also buy aftermarket sleeved piston/cylinders, but the ones I've seen never seem to give you the same performance as the original engine. Here is one site that sells them: Model: XL 800 -- SBT Jetski Engines, Parts & Accessories:

Bottom line is that you would have to get it apart to see what damage you have. The good news is that if it will still run, the bottom end should be OK. My guess you will have to put another $500-$1000 in it to get it going depending on what you find inside.

I don't think the XL800 was made after 2004, so you might want to check the year of the ski (last 2 digits of the HIN will tell you the year).
 

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Discussion Starter #3
Thanks Ernest T. I will try and check the HIN next time i go take a look at it.

I am still trying to understand how the block is made/put together, from what you said I understand that the cylinders are sleeves, in a block. I wonder if the cylinder walls are still in good condition, can they just be honed? And then install new rings and pistons?
 

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I'm pretty sure the original cylinders are Nikasil plated. I've heard that they can be honed if you only have some fairly light scratches that don't go through, otherwise you have to replate them or look at an alternative.
 

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Discussion Starter #5
Damn that's a little discouraging. I want to buy it for about 800 bux. Even with all that is needed is it still a decent deal?
 

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Still sounds like a good deal with your mechanical skills if the ski is in good shape otherwise, and not too many hours. Those skis generally go for around $4000+ in good running shape.
 

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Discussion Starter #9
What do you think about the cast iron replacement sleeves that SBT offers? I assume they are not Nikasil plated... will it perform the same to original?

BTW Ernest really appreciate all the knowledge you have shared it is helping me to make a decision.
 

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What do you think about the cast iron replacement sleeves that SBT offers? I assume they are not Nikasil plated... will it perform the same to original?

BTW Ernest really appreciate all the knowledge you have shared it is helping me to make a decision.
I've never used an SBT top end kit myself, but have heard other say that they do not perform as well as original. I don't think that they are plated, but Nikasil plating may be an option............I'm just not sure. I'd give SBT a call and see what they tell you. I think that they also do the Nikasil replating there at SBT. I'd look at trying to repair the one bad cylinder, either with a light honing, or replating then a new piston.
 
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