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spark plug trouble every ride

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bike is a 2001 yz250f. it seems every couple rides and some times every ride the plug stuffs up. it has a little bit of corrosion on it and one time it had heaps of corrosion. im sick of it. it seems i have to change it before every ride. i have known the bike my whole life and owned it for the last 3 years. today it had a charcoal black tip and further up it was wet. it had very very little corosion. its only started happening the last few months. which also happens to be the same time my dad started riding it as a bought a new one. the engine is pretty old could worn rings or piston or some thing like that be the cause. im thinking the spark plug cap is old and worn letting moisture in when a wash it causing it to corrode. also my dad is very slow.kind of just toots around. would this have some thing to do with the matt black tip?

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How many hours do you have on your piston/valves/head? If you have high hours, you are probably burning oil through ring blowby or worn valve guides thereby fouling your plug. Corrosion on your plug could indicate a blown head gasket, you would be losing coolant and running hot if this was the case. I hope this will give you some help. good luck

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I am not an expert but if your dad is just putting around on it perhaps it's time to lean out the mixture

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Plug fouling on an old engine is a good indicator that the piston and rings need replaced.. The first thing I would do is pull the jug and check things out..

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yeah its about 250 hours and never even adjusted valve. but it still has heaps of compression. i want try rebuild it but i couldnt do any more than piston and rings and maybe cam chain. i wouldnt know how to do valves or any thing. it has also started to become hard starting when cold. starts first kick when hot though. what do you guys think? how to rebuild if i did it my self? what if i put it in the shop?

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it now seems like it only starts cold with out the choke. it used need the stoke

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Clean the carb change/clean air filter if starts with out choke.

If you have corrosion on your plug you have coolant/water inside cylinder if not is impossible to have corrosion.

250 hs seems to be a little bit too much for that engine, so a refresh of top end and crank would be an excellent option...

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Wrong forum.

This is 2 stroke yz's

The plug on a thumper is way different to the 2 stroke

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Wrong forum.

This is 2 stroke yz's

The plug on a thumper is way different to the 2 stroke

Agreed. Post over in the 250F forum and you will get some better info.

However, if your plug is black and wet, it is possible that you have a bad oil seal on your intake valves. With 250 hrs and no topend maintenance, you are just begging for a catastrophic failure (read uber expensive).

Time for some winter maintenance.

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sorry i didnt realise i put it in the rong forum. i ment to post in the 250f. sorry. thanks for help.

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hey sorry guys but its not burning oil. and the weep hole is not blocked. i think its carb. is it to rich or to lean? is some thing blocked? what do you think

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