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help with 01 250f

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I just got a 01 250f 2 months ago.Already have fouled 6 plugs.I start the bike just like the drill says minus the trottle.I use no trottle at all just the choke.Sometimes it starts first kick and sometimes it takes forever.Once I get it running it will run all day and start right up hot.But after a few rides it want start so I check the plug and its always black as it can be,put a new plug in and it fires right up. :confused:I moved the pilot jet c-clip up one ring but all that did was make it pop and not start.Any help would be appreciated. I'm getting very discourage.Also when i had the pilot jet adjusted different the motor seemed like it never wanted to fire kinda like the kick starter was torn up.But when I changed the jet back to stock It fired up after a few kicks.

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i have the same bike with the same problem and it is being fixed as we speak. your valve clearances will be out and this causes bad starting and fouled plugs, try adjusting the air/fuel mixture screw underneath the carb and see if it makes a difference. but i would suggest that you take off them rocker coivers and check the valve clearances as this was said to the be problem to my mystery :cheers:hope this has helped.

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Hard starting and a black plug could mean many things.

Bad Gas- Try changing the brand of fuel you are using to another manufacturer. Use 93 octane or higher. I actually use a blend of 93 pump and race fuel.

Pilot jet- Too fat a jet and the bike will be hard to start when hot.

Fuel mixture screw- Turn the screw in clockwise untill it bottoms out, but don't force it, go easy. With the bike running at a fast idle, turn the screw out so the idle speeds up and slows down. The point where it falls off the peak and starts to slow down is right where you want your adjustment.

If your peak idle falls down after only 1/2 a turn out, then your pilot jet is too fat. Step it down a size.

If your peak idle is more than 2 turns or more out on the fuel mixture screw, than your pilot is too lean, so step it up a size.

Compression loss- How is the compression? Can you kick it through without the decomp lever? ( if it has an 03 cam, then never mind this, lift the valve cover off and check out those valves anyway.) You should not be able to easily kick through the stroke with out the decompression release. If you can then it is time to check those intake valves.

Too much oil on the air cleaner, or you have not cleaned it in about a month.

Could be any of these things and more, but I figured I would throw some things your way. Maybe it will help you out. I know that there were only two things that ever made my bike hard to start and caused a black plug. Valves hanging open, and bad fuel.

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yeh, considering the year I would check the valve clearances, especially the intakes. they are notorious for stretching on 01's and 02's.

Also when you get it done open the plug gap to 0.040". It helps to make a brighter spark and helps a lot with starting. You should consider throwing a $130 at it and swap the exhaust cam for an 03 cam if it hasnt been done yet too.

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I had the same type of problems with my 01 too, but I have fixed the problem. Traded it in on an 05 yz250,everythings OK now.That 01 yzf250 was my first and last 4 stroke. That bike SUCKED!!!!

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i have the same bike with the same problem and it is being fixed as we speak. your valve clearances will be out and this causes bad starting and fouled plugs, try adjusting the air/fuel mixture screw underneath the carb and see if it makes a difference. but i would suggest that you take off them rocker coivers and check the valve clearances as this was said to the be problem to my mystery :cheers:hope this has helped.

1) Valves out of spec will not change the mixture, and therefore could not be the cause of fouled plugs. They do however seem to negatively affect starting.

2) Your wording is so confusing and vague that I could be completely off here (if so I appologize), but the screw under the carb, the black one, is idle speed adjustment and does not affect the mixture at all.

3) "Them rocker coivers" ain't got no rockers under 'em! This is why we have shims, as the cams directly actuate on the valves/springs themselves; no rockers needed.

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very true about the rocker covers but that is actually what they are called. and stretched valves can mix up the mixture because if the intake valves are always open gasses are going everywhere and cause cause it to lean and richen.

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