having a problem with the bike holding its self in gear going down hill,it seem to runaway (neutral).If i give it a bit of gas,it will take hold again!I"m thinking it's in my clutch!The bike has roughly 3500 km ond nearly 400hrs

 

Sounds like the clutch to me...but not the one youre thinking of though. Its the one way (sprague clutch). Its in the centrifical clutch houseing. Thats what allows engine braking. Its like a roller bearing, except the rollers are ecentric, instead of perfectly round,....it freewheels in one direction, and locks the inner race to the outer race in the other direction.
Im just curious....what type of oil has been used. Have you been using automobile oil? Theres a link between using oils with moly, and one way clutch failure.
Welcome to the forums

 

I'm using Honda Oil from the dealer!I've adjusted the slack adjuster on the outer housing-It's seem's to have helded alittle!The clutch you mention;Is it hard to change?And exactly where's it located?

 

If you go here
(hopefully this link works, its in the ronnies site, in the honda parts finder. Look under clutch, and its #27 in the pictoral. Its called "clutch, one way"
I didnt realize these were that expensive...97 bucks.
If you dont have a service manual, you might want to get one. Theres a nut on the assembly that may be difficult to remove,the drum needs to be held still while breaking loose the nut. and then theres getting the assembly off the shaft...the manual shows a special puller.
Before you buy the bearing, ... get the centrifical clutch and drum out of the motor, .....and test the inner clutch assembly,it should only spin ccw in the drum. When you try to spin it cw, it should engage the drum. If it freely spins both ways, its bad. The service manual will show this.
I didnt want it to sound like i was blameing you for the type oil you use, i was just curious. It could be defective just from use, or it might have been marginally in tolerance when it was made, and now its not.

 

Thanks for your help HONDABUSTER !
I hope i did not sound hastey about the oil--I was just answering your question about the oil.
I was looking for any help possible to correct this problem,It even crossed my mind about bad oil!