Please help me..

[Decidium]

Hello,

I have been having some issues with my bike that I desperately need fixing.
It is good at low rpm, but when I start revving it it vibrates and just won't let me get up to speed. It also makes a rough sound and seems to rev up and down when at full throttle. It still has compression, the spark plug is fine (just bought an NGK B6HS) and the engine is running a good mixture. I am using the highest quality fully synthetic racing oil built for high RPM and I am using 95 octane petrol.
The clutch arm is very close to the carburetor, but I have tried to adjust the clutch but I can't fix that problem. I had a look at the bucking bar and the ball has pushed a dent into it which may be causing the arm to be so far back, but I am unsure.
There is also this thud sound every so often, but only really when I try and go fast. The sound is sporadic and is not consistent.
The thud sound makes me think it is a bearing problem but I really don't know.

I am getting really frustrated as I just can't figure it out.
Any help is GREATLY appreciated!

Gareth.

 

[crassius]

I would first take off the clutch and reseat it to be sure the factory got it straight and fully onto the end of the shaft.

 

[darwin]

Any vacuum leaks with the intake?

 

[Decidium]

How do I go about that?

 

[Fabian]

Make sure that the engine mounts are securely fastened to the bicycle frame.

Rotate the clutch arm to the proper position by moving it two notches on the spline.

Check for carburettor to manifold air leaks and make sure the throttle slide cap is screwed all the way down.

 

[Deleted member 12676]

that engine vibration is the mother of many problems so please fix that.
How to is explained on my site. click on my signature link