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Discussion Starter #1 (Edited)
2001 Honda Foreman 450 es quit shifting. I went thru the repair manual and trouble shot every connection and when I was done the repair manual said faulty ECM. I replaced with new one and it shifted thru the gears about a dozen times and quit shifting again. Not 100% sure the ECM was the problem in the first place. Any help would be greatly appreciated
 

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UPDATE! Came home from work and bike was shifting fine with no issues. Was test driving and had to make adjustment to Throttle stop screw since a snorkel kit was installed. While adjusting it quit shifting again. Does this possibly have something to do with rpm's not being right?
 

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No - sounds like a wire is being stretched causing a poor connection or it's a heat issue - keep me posted.
 

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No - sounds like a wire is being stretched causing a poor connection or it's a heat issue - keep me posted.
Thx for the info! Starting to think that may be the issue. Came home again and started up and shifted thru the gears just fine. Did notice the fan didn't turn on. I turned it off and just turned the key to the on position and the fan kicked on. So I started it back up and the fan stayed running but wouldn't shift gears again. Are these made to not shift when getting too hot?
 

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Not that I am aware of, but the more technology they incorporate into the design, the more problems that arise and it all points to the ECM, but if the ECM is getting faulty signals due to faulty connections all kinds of weird shit happens. Not every scenario is covered in the service manual. I was working on one (not Honda) that specified a ground connection at a pin on the CDI when the key switch was on but no connection when the switch was off. It had just the opposite - turned out to be a faulty ground on the brake light and coincidentally a broken filament in the taillight bulb shorting the brake light to the taillight inside the bulb - the CDI was looking for an 0 input at the pin when the brake light was on - due to the faulty ground at the brake light, the light would not illuminate and caused a 1 input at the CDI preventing spark. I had a clue the ignition system was working because it generated one spark each time the key was turned on and one spark when turned off. Repaired the ground and installed a new bulb and spark was restored.

You will have to play with it a bit more to try to determine if it's heat related - both engine heat and electrical component heat - turn the key on and wait 10 minutes and check the shifting - if it shifts immediately upon energizing the system, but fails to shift after 10 minutes with the key on but with the engine not running, then the problem is probably a faulty electrical component - if it shifts fine after setting turned on without the engine running, then quits after running the engine, it could still be an electrical issue, but you need to determine how long it has to run and at what speed and at what engine temperature the shifting fails - it might be heat related to the engine.

Good luck and let me know what you determine.
 

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I appreciate the advice. It all pretty much makes sense. I will start with the key on but not started and see if it stops shifting after a period of time vs with it started. It seems to happen within the first 15-20 mins. I think that will at least point me in right direction.
 

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I believe the problem is solved! I noticed the oil cooler fins were clogged with mud and the throttle was sticking due to throttle housing on carb full of mud. Cleaned the hell out of both and rode several times over the weekend and everything seems to be back at normal, (go figure). Son's bike, and like everything else they only clean half ass! Lol
 
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