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Discussion Starter #1
Hi guys I am a newbie and very new to pwc's. I have a 2003 yamaha gp800r, my problem is that while running it will die and after further look into it I noticed the spark plug was getting shut. I guess the Liston is barely hitting it and closing the gap on the plug. I had the motor rebut by a local dealer about 2 years ago these belong to my in laws at the time and they never did anything about the issue after the rebuild. Now I bought them from my in laws and plan to fix the problem. I am fairly familiar with engines and things like that, is there a chance that the gasket that was put on the heads is to thin maybe the wrong one and it is causing the piston to hit the plug?
 

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If the problem has been happening since the rebuild, I'd guess the guy used the wrong type (length) of spark plug, or the wrong thickness of head gasket, or even the wrong size of piston.

If the problem has just started occuring now 2 years after the rebuild, I'd guess that the engine is failing again.
 

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Discussion Starter #3
My father in law said he changed the spark plugs after it started acting up. Bit I will be checking that tomorrow to make sure. It has been doing this since about 2 months after the rebuild. I will have some free time tomorrow so the first thing I'm gonna do is check to make sire the right plugs are in there, if that's not it I'm hoping it's not the piston and may e just the gasket
 

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Problem with a rebuilt engine is how do you know what the "right" plug is. The NGK-R is a very common plug. I'd measure the thread length on the plugs you have and take it to an auto parts store and try to find one that has a 1 or 2 mm shorter thread length, and see if that will work.
 

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Discussion Starter #6
Well after further inspection on these things my in laws let them sit so long that am gonna have to do some work on them to ge them to start right first then I can start on the plug issue.

Any tips on what to do if these things have been sittin more than a year? I'm gonna drain the gas tomorrow and see how that goes.
 

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Discussion Starter #7
After messing around with them for a while today I found that they aren't getting any fire to the plugs. Any thoughts?
 

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Discussion Starter #9
I got them to fire yesterday afternoon sorry I didn't update. But they still won't start. So I am going to pull fuel lines and make sure no clogs and then rebuild the carb
 

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im having the same problem, try some starting fluid in the open carbs (take off the airbox and spark arrestor) spray for like 3 seconds in each carb, close the choke and it should catch 2-3 cranks!! it got mine running but then it dies lol
 

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i had the same problem whit mine, after trying and trying i finally pulled of the head to find if there where any problems. I found a complete defect cylinder and piston! this was only from a 6 year old ski, the dealer told me he sees this kind of problem after 10 years of use. Mine only took 5 and died.

Now getting new sleeves and a new top and kit.

My PWC started at the beginning but keeped failing while i was on the water. Very annoying!
 

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Startig fluid is never a good idea on a two stroke that is not getting fuel washes the cylinders and rings, good way to ruin a good engine. use gas and oil mixture poured or sprayed in carb or intake.
 
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