2006 Gas Gas 300 Top rpm/Open throttle range problem

[joppiesch]

Good day guys

I have Three Gas Gas 300s. I have sorted out the jetting on the other 2 and they are running 110% with loads of crispy power through the entire rpm range.

However the last one I'm having difficulty with the top rpm range. From closed to 3/4 throttle range it has loads of power and torque and runs perfectly, but as you fully open the throttle it still accelerates, but I can feel its low on power, especially compared to the others. Its like it runs better on 3/4 throttle.

Now I have the stock gold needle in a brand new Keihin pwk 38 mm carb, with a 42 pilot jet. I have played with numerous bigger main jets as I thought with the top rpm range being the problem that the main jet might be to small. However there is no difference even if the main jet is 20 sizes bigger up to 200. I have numerous sizes slides (5-9), Main jets (145-200) and Pilot Jets (38-48).

I did notice if you lower (richer) the needle clip the bike has more power at open throttle, which i don't understand, cause thats the main jets function. So the clip is at the lowest slot of the needle at this stage.

Is there anything else I could do maybe with an exhaust, silencer, new spark plug, carb slide ??? Maybe any recommendations for a thinner/other needle?

Cheers
Joppie