does anyone know about any potential problems with the transmission on a 2003 - YZ450F

Never heard of any yet. Why? are you having trouble with you tranny?

ya, it keep slippin uphill, can't get enough power

ya, it keep slippin uphill, can't get enough power

Your clutch is slipping from what you described. IMO

You need to inspect your clutch plates, basket and cable per normal maintenance as described in the manual...simple and very effective.

What exactly do you mean by "slipping"? Manual transmissions don't slip. Clutches do, however, and transmissions will develop problems staying in gear.

Clutch slip is characterized by rpms that rise with the throttle but don't translate directly into higher speed. It's worse in the higher gears because there's more load on the clutch then. If you can run your bike on some pavement, you can spot that right away. Lack of free play in the clutch cable is the most likely cause, but you could have plate or spring problems, too.

Transmissions will "skip" out and into gear. The locking dogs will wear and lose their ability to hold under a load, and the gears will separate from each other, sometimes catching hold again immediately, giving a jerking sensation. When it gets bad enough, it will just jump out and stay out, or occasionally jump all the way into another gear. Replacement of the gears and shift forks involved in the problem is necessary.

Sometimes people will confuse a simple lack of power, or another engine performance problem as a problem with the trans. Be sure of what you're seeing.

a year ago I took it to the shop, they put in new shift forks and new 4th gear. now it's slipping in and out of gear, just like it did a year ago. any thoughts?

when i shift, i don't use the clutch -- could that be the problem?

Yes, that is the problem, the fact you now need to change the selector fork again (twice in one year) seems fairly obvious.

I have raced enduros for a few years and have been riding for about 15 years now and I have never had to replace any transmission parts. Apart from a selector shaft seal or two. Use the clutch your engine will thank you in the long run :)

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