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djo269

bike stalls alot on tight mx track

29 posts in this topic

I took my newly acquired 03' yz450f to this track that has tight turns and close obstacles and I kept stalling the engine over stuff. I tried going down to second gear and still I kept stalling over half the track. It sucked cause I was on the face of a jump a couple times and it almost spit me over the bars. I was pissed when that happened. What can I do? Change the gearing some? I upped the idle to help, which did little to nothing. (Please help) :D

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I have the same problem with my '01 426. I'm usually on the gas when it cuts out so I flood it on top of being stalled. I really make Yamaha look bad because everyone on the track sees me spending more time kicking then riding. I have actually given up trying to kick it to restart it. I just push it up a hill, take a nap, and then bump start it to get it going. :D

I'm using the clutch religiously in the corner, but sometimes I just miss it and it stalls. I guess I'm going to have to try to clutch it a little earlier coming into the corner and rev. it a little more going out.

Or I just have to switch to a track that doesn't have any turns.

I look forward to the responses because I'm having the same problem.

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I don't have this problem with my yz420f. My gearing is 14/49 too! On my track I'm in second gear the whole time because the track is not big (Metcalfe in San Jose). If you are having trouble stalling I'd say put a 13 sprocket on the front $20 and go for some flywheel weights. I don't know how you ride and without seeing you ride it is hard to say. You shouldn't have to religiously work the clutch on a 450 cc motocrosser. You are either not aggressive enough in the corners and off the face of jumps or the above mods are needed. My bike can crawl from second gear but I'm usually trying to get through a corner as fast as I can and I'm on the gas approaching a jump. Hope this helps. Try giving your bike to a more experience rider at your local spot and see if they can maybe pinpoint your best options. Were all in this together....good luck man! :D

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One of the things that helped me out in racing and riding a tight track was just turning up the idle a bit. It's not as effective as a fly wheel weight or using your clutch perfectly, but it's cheap and it does help :D

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I would think running rich/flooding the engine with a quick twist would cause a stall instead of a lean condition. :D I know having a clogged air filter causes stalling tho. Hey thanks for the links Greyrider I might get one soon. I dont plan to go back to this particular track anymore so...The other tracks I ride, I can hold the wick open harder and longer so I might be good with stock flywheel but we'll see...Man this bike rips!!! :D

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03 450 YZF

Flywheel, 4 or 6oz DR. D and up the idle a LOT!!!! will CURE the stalling problem.

Changing the gearing will smooth the HIT out if you want.

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When I first rode my 03 It was stalling a lot, so much in fact I thought somthing may have been wrong with the bike. I would listen to cobra427's advice and let someone with seat time on a bike like yours take it for a spin before I would invest in any mods. I learned to ride it differently and turn up the idle. I have noticed that the bike favors high RPMs, If i run it so I am allways pushing it, It will not stall. Run it a gear lower than you normally do to keep the revs up. Try not to engine brake, pull the clutch, break hard, downshift then put power on hard enough to activate the pump. The light flyweel is the issue, but if you ride it very agressive it can be your benifit insted of your handicap. Its took me a month or two before I learned to ride the bike without stalling it. However, if your track is really tight you may have to do some mods like weights as its hard to ride aggresive in all conditions.

Hope this helps.

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Alot of good ideas from you all, thanks. I took to my favorite track today. Things started out really soft,deep and loamy but as practice went on it became kindof a hard/soft pack which is what I like. The guy that owned the bike before me had a secondary gearing of 14/49. Which supposedly will exaggerate the "hit" even more. My biggest problem is not finding enough traction to accelerate. The stalling issue was just with that one track, which I dont plan to go there anymore anyways. I like the hard hit and instant response, I guess I need more saddle time on it and find a really good rear tire. I am getting pretty good at clutching it on the track to get it to fire up when it stalls. Usually if you are in 2nd or 3rd gear and have enough momentum you can fire up a dead engine with the clutch. Is clutching to refire the engine hard or bad on the engine? I wanted to say this again"This bike is off the chain!" 03yz450f

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I have buddy that races the 03 YZ 450F his was stalling in the corner bad he put a 50T sportket in the rear. Left the front sprocket alone and heavier fly wheel. work great now!!!!

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You can bump start it with the clutch, but I have been told never to pull the hot start while doing so. This was what I was told, I dont know if there is any truth to it.

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i noticed my 01 426 did the same thing and i found that my spark plug wire kept popping off after I changed it out and put the gas tank on the wire, also make sure your spark plug is nice and clean. you may also want to try running a little hotter plug.

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My biggest problem is not finding enough traction to accelerate. I like the hard hit and instant response, I guess I need more saddle time on it and find a really good rear tire. I am getting pretty good at clutching it on the track to get it to fire up when it stalls. Usually if you are in 2nd or 3rd gear and have enough momentum you can fire up a dead engine with the clutch. Is clutching to refire the engine hard or bad on the engine? I wanted to say this again"This bike is off the chain!" 03yz450f
Ease of bump starting is one of the big advantages of Auto Decompression. You can do the same thing with manual decomp, but it takes a lot of practice to do it quickly. Clutching the engine back to life is not hard on anything.

Traction is one of the things a heavier flywheel will improve. Whereas, in stock form, you grab some throttle and the rear wheel blows up, with the addition of 5-6 ounces (when using a welded weight. bolt-ons have to be heavier), the same throttle grab in the same place with the same tire will be less likely to produce runaway wheelspin, and more likely to produce a runaway motorcycle. Or a wheelie. It WILL still be a beast, and it will still be all the way "off the chain", if not even more so. it will just be more under control, that's all. I've never heard anyone say it wasn't a better bike with the extra weight.

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Ease of bump starting is one of the big advantages of Auto Decompression. You can do the same thing with manual decomp, but it takes a lot of practice to do it quickly. Clutching the engine back to life is not hard on anything.

Traction is one of the things a heavier flywheel will improve. Whereas, in stock form, you grab some throttle and the rear wheel blows up, with the addition of 5-6 ounces (when using a welded weight. bolt-ons have to be heavier), the same throttle grab in the same place with the same tire will be less likely to produce runaway wheelspin, and more likely to produce a runaway motorcycle. Or a wheelie. It WILL still be a beast, and it will still be all the way "off the chain", if not even more so. it will just be more under control, that's all. I've never heard anyone say it wasn't a better bike with the extra weight.

:D:D:D

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Heavier flywheel for sure. I have an 04 YZ450F and i was not sure who was riding who at times.

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