Motorcycle Repair: throttle cable SNAP back- 1972 cL175

Question
Bill,
I have installed a new throttle cable on my 1972 cl175 K6 and the throttle does not SNAP back to return/ idle position. Is it most likely weak springs? What other factors are there to consider?

Answer
James, it sounds like it could be any of the following:

a. The cable is mis-routed and hanging up. Normally the cable routes around the steering head and runs down the left side of the frame and then over the top of the carburetor bodies. Route the cable ABOVE the forward fuel tank mount on the left side.
b. There isn't enough slack in the cable ends... adjust at the throttle housing and/or carburetor tops.
c. Carb slides are in backwards...  cutaways go towards the airfilters. It is a 50-50 deal as to whether they are in right or not. Common mistake when both carbs are taken off that same time and the cutaway/slide slots are not recognized as being unique to each side.
d. Lube up the throttle drum, where it turns on the handlebar.

Disconnect the carb tops and check for cable motion. If it moves freely in and out, then you have carb slide issues (backwards, varnished up, corroded, carb needle not fully inserting into the needle jet hole) and you will have to correct that. Try putting a slide into the carburetor body without being hooked up to see if it moves freely up and down inside the carb bore.

The carb return springs are plenty strong enough to return the slides to idle position in normal conditions.

Bill Silver