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The Dreaded Miss

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Well, a friend of mine rode my husband's 03 WR250F, and instantly fell in love with it. About a month later he went out and bought a used 01 WR250F. After buying it he was very disapointed in it. This guy is a pretty big guy, but he is a good rider. He told me he just couldn't climb anything on it, the bike dies all the time. He finally took it in to the dealer and they said it has a terrible mid range miss. :cry: He as about given up on the bike due to his fustration, and go to something different. If the bike is not what you want I respect that. I just hate to see someone come to the conclustion that it is the wrong bike for them, when it doesn't even run right. Anyway.....My husband has an 03 CDI box off his bike which I am guessing won't work. Does anybody know? :cry: Will an 02 box work? I know he does not want to spend $400 on a vortex, so I am just looking for a used stock box that wont cost a bundle. Any ideas?

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amber,

> He finally took it in to the dealer and they said it has a terrible mid range miss.

well, that was a helpful dealer. :cry:

did they suggest what the cause(s) might be? or did they just hand it back to your friend after stating what he already knew?

the way i see it, there are two potential causes of a midrange miss; one is ignition related, the other is carb related. neither is really difficult to diagnose, and certainly a simple midrange miss is not cause for selling the bike. so...

part A)

certainly if the CDI module is cooked, that could cause a miss. or, if the TPS is borked, that could do it as well since it may be feeding the CDI module the wrong info. the '02 WRF CDI is close enough to the '01 WRF CDI that it should work straight away. however, the YZF type CDI may not work due to differences in the electrical systems of the two models.

part :cry:

a midrange miss can also easily be the result of hosed up carb jetting, or simply gummed up jets or needle. perhaps this '01 WRF was stored for a while, and the old gas jelled a bit around the jets and needle. so as a first step, disassemble the carb and use copious amounts of carb cleaner to get everything sparkling again. or maybe the carb has sucked in some air filter oil -- a common problem with these high compression four strokes. in any case, a good carb cleaning is a prudent first step. it also gives you the chance to inventory the current jets and needle, which will aid jetting improvements later.

some questions:

how does the air filter look?

how does the spark plug look?

how does the tail pipe look?

when was the carb last cleaned?

did it run correctly when he bought it?

did it start acting up after some work was done?

what other work has he or others done to it?

jim aka the wrooster

'01 wr250f

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Thank Wrooster for the well thought out answer. :cry: I guess the dealer is saying that it is an ignition miss. Sorry, I didn't realize a jetting problem would be refered to as a "miss". My bad. :cry: So I guess the only cure is to find an 01 or an 02 CDI box and hook it up. I have a feeling that the jetting may be off too. I know from experience that it can take a while to get the carb ajusted and jetted properly, and this guy has never really taken the time to really work on it. As far as mods go, I think the only thing the guy did was the throttle stop, end cap, and I am guessing the grey wire (he doesn't know). I would like to just get the box stick it on, take the carb off and see what is in it, clean it up, and then give it a once over. This guy is used to old school 2 strokes and I think the new four strokes can be harder to get tuned correctly. There is just so much more areas to adjust. Thanks again Wrooster. :cry:

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He can buy my bike. I just pinched another tube today trying to put a new tire on... Thats the 4th one this week. 50 bucks worth in tubes. I'm fed up and thinking of selling it. :cry:

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I almost took my 03 back the day after I bought it because it had a very aggravating miss when held at steady throttle. Upping the pilot jet to a 42 cured the problem. If I had it to over, I might have went with a smaller PAJ instead.

Just an example of how the jetting can cause "the dreaded miss". I wouldn't bother to clarify anything with the useless dealer. Surely there is a TT'er in the area who can look the bike over for your friend.

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Hey amber just thought I would say HI.I hope marty can get that thing running right before he decides to sell it.He might decide he likes it.You sure caght some nice AIR yesterday at Hollister :cry: :cry: :cry: :cry:

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He can buy my bike. I just pinched another tube today trying to put a new tire on... Thats the 4th one this week. 50 bucks worth in tubes. I'm fed up and thinking of selling it. :cry:

:cry: :cry: :cry: I just hate that.

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Barton, Thanks for your imput. I don't know if the dealer did some kind of test, or if they are just assuming that it is the CDI causing the miss. I will have to let him know that he needs to play with the jetting more before we assume the CDI is the culprit.

JRambo, come on, my air wasnt' that big. :cry:

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