2008 Ktm 250 Xcf Review
2009 KTM 250 XCF hare scramble race bike, with a race winning pro level rider. The problem is this bike won't complete a race without cutting off. Carb has been jetting and adjusted and setup with proven winning spec's with no change. Race starts and it runs as it should but give it 25 to 35 minutes and it cut's off. Hard to start back but will eventually. Rider was told over and over nothing wrong with bike "your just stalling it". He brought the bike to me and asked if I would take a look. So I check over the bike and the carb everything clean as a whistle. I had a friend try it in about a 4 acre grass bottom. Wide open as he could hold it, must have made about 10 laps, come out of the turn rolled on throttle it just fell on its face and died. When you start it up it runs but it continues to stumble off idle. Let cool it's good to go again for another half hour. I'm thinking there's something electrical going on. I have checked everything (hot and cold) that can be checked by ohm meter without finding a problem. KTM did change a cdi box right after the purchase. Anybody heard of or had any problems like this?
Follow the path of the fuel system from the cap vent to the carb. Verify the cap vent works properly, then follow the fuel path and look for places that could introduce heat. Four-strokes with their compact packaging have proven to be much more susceptible to fuel vapor lock issues. They are easy to solve if that proves to be the problem.
It does have a extended fuel line to allow for an in-line fuel filter. I will double check the fuel path and maybe do away with fuel filter and shorten the hose and test again. Thanks
I checked the fuel lines over good today. The vent hose didn't seem to have any restriction's but it was very long running along the frame under the tank and down by the carb ending up at the swing arm pivot. I replaced with a short hose behind the number plate. Gas cap is out of the equation because it has an ims tank with a dry break. It has an unusually amount of clearance around the head, not really even close you can lay your hand on top of the valve cover. Checked the screen in tank and it was clean. Replaced the extended fuel line and filter with a short fuel with the largest id possible. No kink's easy flowing.
Took it out for a test run it was misting rain and almost dark. I just ran about 600ft back and forth it took ten minutes and it started cutting off. Not going dead but I had to feather the gas to keep it running back to the shop. Pulled into the shop held the throttle around 4000 rpm and it just popped, cracked and stumbled bad. Pulled the choke while holding the throttle at the same time made no difference at all. If it's a fuel problem I'm still puzzled?
close the gap of the plug (if it´s a new one... otherwise get one) to half and see if it´s better... easy, simple and fast, might worth a try... :cool:
could be also very thight valve clearance...
I can't help you much. I did not get the problem fixed. I talked with a KTM factory tech at the races he was betting it had electrical issues. I talked to CPW about any carb problems they also said "sounds like electrical problem". KTM tech and CPW said "take it to the dealer they should fix it no charge". I talked to the dealer and they said to bring it back they would fix it. I have not heard anymore about it. I saw your post and tried to contact the owner with no luck.
I was just to the point I was going to spend his money switching out parts. If there was a chance the dealer would fix for no charge I thought he should give them a try. I have not seen or heard from him either at the races or by phone so I don't know how it came out.
Thanks anyway, appreciate you replying.
I think Matt90GT has sorted it for us, will give feed back once we've tested again tomorrow.
Brad Russ said:
Thanks anyway, appreciate you replying.
I think Matt90GT has sorted it for us, will give feed back once we've tested again tomorrow.
Let us know, be interesting to know what you found.
BSWIFT
Sponsoring Member<BR>Club Moderator
This sounds like a heat related electrical problem at the stator. If you have the factory spec for resistance of each terminal, meter it cold. Use a hair dryer or heat gun and watch your meter. The resistance will start to climb. Don't use excessive heat. If the resistance climbs out of the tolerances AND you can still touch the stator bare handed without burning yourself, you've likely found your problem.
A question for the rider, "does the cut out happen AFTER a open straight and followed by tight corners?" The open straights would allow the engine to heat fast and then the slow turns would not allow it to cool down sufficiently with the lack of air movement around the engine case. A stator in good shape should only see a modest increase in resistance even under the above situation.
I finally got in touch with the owner of the bike and asked what the dealer came up with on the bike. The dealer told him that they replaced the carb with a brand new one and also replaced the head pipe with a new one. They then jetted the carb and told him it was ready to pick it up. He picked the bike up and took it for a test ride and did the same thing. Dropped it back off at the dealer and told him it was doing the same thing. The dealer kept it a few days called for him to come pick it up and said "had to adjust the carb" He says it's been running fine ever since.
It just seems strange to me that the dealer would have such a hard getting 2 brand new carbs to run. (The one that came with the bike and the replacement). I have to wonder if the dealer is telling the full story.
Source: http://dirtrider.net/forums3/threads/2009-ktm-250xc-f-problem.172371/
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