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Discussion Starter #1
Just purchased a used Yamaha 2000 XL700 . It was not a rental.

The first time we took it out, it ran great although it smoked quite a bit. The second time was yesterday and it would not stay running.

It kept dying shortly after applying the throttle. It would get up to full speed for several seconds and then shut down.

The only way I could get it re-started was to choke it.

I pulled the plugs back home and they were oily wet black. I don’t understand because that would ordinarily mean it’s too rich, but having to choke it to crank means the opposite.

The fuel filter had a little crud in it, but I didn’t notice any water in the fuel.
 

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You wrote me about your jetski stalling and told me to tell you what it was when i figured mine out because it sounds like we were having the same problem. Well it turns out i blew a hole in one of the pistons so the thing for you to do would be a compression check and make sure thats not your problem!! If it is then you better get ready to hand some money out!!
 

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Discussion Starter #4
You wrote me about your jetski stalling and told me to tell you what it was when i figured mine out because it sounds like we were having the same problem. Well it turns out i blew a hole in one of the pistons so the thing for you to do would be a compression check and make sure thats not your problem!! If it is then you better get ready to hand some money out!!
Wow, sorry to hear that.

I tested both cylinders twice with two different gauges just to be sure. I got 140-142 on the front and 138-140 on the rear.
 

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Discussion Starter #5 (Edited)
Try replacing the plugs and see how the jet ski will run. You have a 2 stroke motor in the ski so chances are you just fowled a plug.
I cleaned the plugs real well with a wire brush and verified the gap was correct.

Even though it's a two-sroke, the smoke is excessive from this engine. Also, the water coming out the back has lots of oil in it.

I can't imagine these things being engineered from the factory putting out this much pollution both with smoke and oil. Something is amiss.

Another clue is that the idle is now too high. I didn't notice that yesterday out on the water.
 

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You could have an air leak somewhere causing the higher idle and use of choke. Cleaning your plugs usually doesn't work. Could need a good de-carbonizing very soon. Sea-foam or yamaha ring free. Mercury makes some good products too. Check your oil pump setting and cable.
 

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This sounds like a blown engine. I know you said you did a comp test but you also said it had excessive smoke which comes from oil. This amount of oil will sometimes mask a lightly scored bore. If you have just bought it the previous owner may have adjusted the oil injection to make it run. DO NOT keep running the engine or you will completely destroy the bore. If its still managing to start then it may only need a minor top end rebuild at this stage.
 

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Discussion Starter #8
This sounds like a blown engine. I know you said you did a comp test but you also said it had excessive smoke which comes from oil. This amount of oil will sometimes mask a lightly scored bore. If you have just bought it the previous owner may have adjusted the oil injection to make it run. DO NOT keep running the engine or you will completely destroy the bore. If its still managing to start then it may only need a minor top end rebuild at this stage.
You may be right.

For now, my plan is to put two new spark plugs and a new fuel filter and hope that it runs well again. If not, I'll run it on the hose and spray around with WD-40 to see if that makes the engine slow down or speed up to check for leaks.
 

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Its your choice salt dog. However, think about it before you go doing more damage to the motor. WD-40 and plugs wont do the job.
Too much oil? adjusted to fill the combustion chamber with oil so it gives a false compression read!
Stopping at high revs? piston catching once it heats up!
High idle out of the water? Adjusted high so it will idle under load in the water then will sound as if its leaning out on the trailer!
 

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When pulling the plugs out, check them both for uniform color. If one is very light or aluminum shaded you probably have a problem. You can ground the spark plug wires and try holding your hand over the plug holes to see if you have good compression but chances are that it's a no go.
 

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Discussion Starter #11 (Edited)
When pulling the plugs out, check them both for uniform color. If one is very light or aluminum shaded you probably have a problem. You can ground the spark plug wires and try holding your hand over the plug holes to see if you have good compression but chances are that it's a no go.
Both plugs were oily wet black. I'm not sure I understand your comment about checking compression with my hand uless you're saying it will tell me if the oil is masking the true condition of the rings.

You may not have noticed my post above about checking the compression with two different gauges.


SaltDog
 

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Discussion Starter #12
Is it easier to replace the rings by taking the engine out or leaving it in?

Also, how much should I expect to pay someone to do a top-end rebuild versus doing the job myself? I'm looking for rough numbers here.
 

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Discussion Starter #13 (Edited)
Is it easier to replace the rings by taking the engine out or leaving it in?

Also, how much should I expect to pay someone to do a top-end rebuild versus doing the job myself? I'm looking for rough numbers here.
Talked to a mechanic yesterday and he says $300 to rebuild the carbs and that includes putting it in the water and tuning it out.

He says a top-end rebuild would cost $600 but would include rebuilding the carbs.

He warns to not drive it and risk major engine damage and says it doesn't take but a short distance to happen. Not that I plan on doing that.

Anyway, he's suspicious of the ten year old oil injection system and indicated it may be supplying too much oil which is a whole lot better than not enough.

Thought I'd report.
 

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Discussion Starter #15
So is one of the cylinders slightly scored. Cause if it is it will probably need a little more than just rings.
I haven't pulled the head to look. I was just getting estimates based on your gut feeling that the engine has an internal problem.

That $600 estimate includes going with an .020 oversized piston if necessary.
 

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Discussion Starter #16 (Edited)
I'm not getting much advice, but I'm going to keep posting each step along the way to fixing this issue in the hopes of helping others.

The next step is to make sure I have good clean fuel of the right mixture which means siphoning out the old fuel. When I pulled off the hose at the tank I could see inside and there was about a tablespoon full of black crud on the bottom of the tank.

Remember, there was also black crud in the fuel filter. Even if this dirty fuel isn't what is causing the problem, I feel a lot better about keeping that garbage out of the carbs I'm getting ready to rebuild.

If you want to quickly check the condtion of your tank, pull the hose and look inside. You may be surprised at what you find.

SaltDog
 

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People have given their advise. It's up to you if you want to believe them. This mechanic you said quoted on the re-build should always drain and clean the tank on a re-build. It is standard practise for any mechanic when doing a re-build. Why don't you just pull the head off and see for yourself. If its not slightly nipped up, it will only cost you a cheap head gasket.
 

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Discussion Starter #18 (Edited)
People have given their advise. It's up to you if you want to believe them. This mechanic you said quoted on the re-build should always drain and clean the tank on a re-build. It is standard practise for any mechanic when doing a re-build. Why don't you just pull the head off and see for yourself. If its not slightly nipped up, it will only cost you a cheap head gasket.
I don't mean to sound ungrateful, I appreciate the advice. The reason I doubt the engine is bad is because I know and trust the guy I purchased it from. He purchased a new Yamaha because this one has been so good. Even so, once the new fuel and filter is installed, I'll just run it long enough on the hose to see if it made a difference and will also check for air leaks.

SD
 

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Thats cool. I just think your going around in circles. Until you pull the head off, you will keep damaging the engine more. And if it is fine, a head gasket is cheap anyway.
 
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