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Old 02-21-2013, 07:07 AM
Russ McClay's Avatar
Russ McClay Russ McClay is offline
Motorized Bicycle Senior Member
Join Date: Jan 2013
Location: Taipei
Posts: 85
Default Re: First time firing up the engine, problem! :(

Hi bairdco!

Your post was extremely helpful for me.

I've already got 270 miles on my first build (66 HT / NT carb). But still dealing with a little 4 stroking in the mid-range and some loss of power WOT. So been doing a lot of reading here.

I had been using the cable adjustments at the throttle and the carburetor cap to set the idle. I didn't understand why the idle set screw did nothing.

I followed your simple instructions of how to adjust the cable and saw the light! I spent ten minutes on it:

1. First removed the air filter housing.
2. Loosened the idle screw almost all the way out.
2. Then loosened the lock-nut on the cable adjuster on the top of the carburetor cap and the lock-nut on the throttle end of the cable.
3. Then observed the barrel as I twisted the adjuster nuts at both ends so that the barrel was all the way down. I started with twisting the adjuster on the carburetor cap so it was all the in and then finished using the adjuster on at the other end.
4. Then tightened the lock-nuts both ends.
5. Then observed the barrel as I adjusted the idle screw to see that there a slight gap at the bottom.

I then pedaled, popped the clutch...and nice! It was running and idling sweet. And giving it the gun (twisting the throttle) is smooth and returns back on release easily.

I knew I was adjusting the throttle cable wrong but I didn't know the right way. Now I do thanks to you. =)

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