I see oil on the spark plugs when opening them.
big problem?

 

Is it really oil??? or just unbernt fuel. Do you have blue some comming out the exhuast? Is it hard to start? Low on power? Have you made any changes (mods) recently?

 

Are you sure it's oil and not just carbon buildup?

If you have oil in your head you probably have a bad gasket or a crack somewhere in the engine.

 

nothing comming out the exhuast, it's start well but low on power when in low rpm (less than 4000).
there are no mods on this quad.

 

My guess would be that your seeing a wet plug from unbernt fuel. And the dark color is carbon build up. Make sure to keep your filter clean. Put a new plug in her and run it for about 10 mins or so. Then check it and see how it looks. WHat is your elevation. You may be jetted to rich for where you live. If it's not depositing an oil film on your tail pipe or producing blue smoke, I doubt it's your rings.

 

Thanks for your help

It doesn't smoke at all.
I have put new spark plugs two weeks ago, there was a lot of carbon on the old plugs, one of them was totally covered and didn't work at all (it ran on one spark plug), they both were wet on their sides. I put then the new plugs and now checked them again and they are wet again.

Don't know exactly the elevation here but it's about sea level.
Is there a way to check the oil/fuel on the plugs to know if it's oil or fuel?

 

If the plugs are only 2 weeks old and they are already black and wet then you do have reason to be conserned. I find it hard to believe that your exhaust isn't also black. I would also think if it was oil or running extreemly rich that would would notice it at the exhaust in the form of smoke. It doesn't have to be a lot. Does the exhaust smell like oil? Are bloth of the 2 week old plugs black or just one of them? You could have leaky valve guides and it's just not bad enough yet for you to notice in the form of ehaust smoke i supose. Have you done a compression check yet to see? Hope somebody else can chime in cause im running out of idea's...LOL

 

not sure if you've fixed the radiator, but the damage could cause some weird problems. At least from your photos, the rad looks wrinkled enough to maybe cause overheating and engine damage. Or maybe its just a weird photo angle.

Also, ensure the choke is pushed in all the way. It sometimes feels in when it's only half way.

I've used a lighter to check oil for indications coolant but never used anything to find fuel except my nose. If I was going to get a lighter near a wet plug though, I'd make sure I was in a safe place so as not burn down the house if I chucked it across the room when it ignited.

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Found the problem - broken piston.
I have traded my beautiful baja [img]i/expressions/face-icon-small-sad.gif[/img] , got a baja X from the dealer.
Have a look at my page.

 

Man that really sucks!
What happened, do they know? (assuming under warranty being an '04)
Was it "pinging"?
Did it get hot?