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2001 WR250F Problems after 03 Decomp Cam Mod

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Hi,

Just did the decomp cam mod on my 01 WR250F. I was not able to completely line up the "I" (on the fly wheel) while having the cam marks level with the top of the head. If I move the fly wheel to line up the cam marks level, The "I" is about 1/4 of an inch to the left of the TDC mark on the lower case. If I move the chain to a different tooth, it is way out so I figure this is a good as it gets. I am counting 13 pins from the 12 o'clock positions. It is all back together and starts fine, but as soon as it gets to a lower rpm it coughs and stalls out.

I have also shimmed my valves and are now within spec, but it still does it!

One thing I have noticed is the cam I ordered was 5UM-12180-10, I see that thumperfaq sayes to order the 5UM-12180-00. This is apparently the same one, or is it?? From what I have read this is a 05-06 p/n. Will it still work?

Before everything was working fine, maybe a bit of a lower idle than normal. I have done nothing to the carb, so dont want to mess with it at this time. Can anyone please give me a tip on where to start diagnosing this problem??

Thanks!

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Either your timing chain has stretched (needs to be replaced) or your timing is off (need to reset). For the 250Fs, there should always be 12 pins between the "imaginary" 12 o'clock marks. For the YZF cams, there should be dots at 12 o'clock for both cams. For the WRs, the exhaust cam's dot is at around 11:30, while the intake cam's dot is at 12 o'clock.

There are pictures at this link that will show you how things should look, however this is for my 06 YZ250F and not a WR.

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I will try that but before I spend the money, as far as the tensioner, do you turn the screw all the way down, or are you suppose adjust it until the marks line up?? How much is too much tension?? Thanks again!

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Download a manual from this link, then read what they tell you to do. The tensioner is automatic, it will push out and adjust itself I believe. Follow the instructions in the manual and you'll always be good to go. :)

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hey,

I just did this a few weeks back and couldn't get it just right, I ended up having to re-time the chain 2 more times... I had to keep my socket on the bolt as a weight to keep the crank at TDC (was off by a tooth on the crank itself.

your symptoms will be that it's hard to start, and it wont' stay at idle with a normal RPM

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