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Discussion Starter #1
Hoping somebody can help me.

Last weekend, I unscrewed the thumbwheel by the float chamber to drain-off fuel after a good soaking in river. It was the wrong screw ... Should have opened the allen screw. :wanker:

I believe the thumbwheel is actually the fuel/air mixture screw. Put it back to roughly where it was, but now stutters when holding revs steady at mid/high throttle.

What should the setting be? Pls note I have the 350cc big-bore kit fitted.

Thanks

Andy E
 

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Put it in gently until it just goes firm, then back out by about 1 1/2 turns.

If you put it in too hard, the end snaps off and you have to buy a new carb.

Did you replace the spring, washer and O ring that goes on the screw?
 

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Discussion Starter #4
The thumbwheel I am referring to can be seen at weblink.

All I did was unscrew it and then, when I realised it was not the drain screw, I re-inserted it until it was full tightened and then wound it out about 1.5 turns ie did not replace any spring or O ring.

How do I cure the hesitation that previously was not there until I messed with the screw?

Thanks

Andy
 

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Take it out again and fish out the spring, washer and O ring... if they are still there.

Examine the end of the screw, it should be a machined point. If the point is broken off you need a new carb and screw, buy a stainless or brass version, not aluminium.

If the end is OK, slide the spring onto the screw, followed by the washer and finally the O ring.

Put it back in the carb, screw in gently til it bottoms out then out 1 1/2 turns
Start and get the engine up to operating temperature
Adjust the idle as low as possible without stalling.
Slowly turn the screw in until the engine starts to slow down and then unscrew 1/2 of a turn. The screw should be in the 1 to 2 turn range.
If less than 1 turn, the pilot is too big - install the next smaller size. If more than 2 ¼ turns the pilot jet is too small - install the next larger size.

Then set the idle speed to how you normally have it.
 

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Discussion Starter #6
Thanks Kev. Ill check again and hope that I have not snapped the pin. New carb sounds expensive...
 

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Discussion Starter #7
Sorry, forgot to ask. Which screw do I adjust for the idle? Is it the other thumbwheel in my photo ie top left? Cheers
 
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