Uneven throttle cables

[20975]

Hi All. I am hoping you can share your wisdom with me. I have recently refurbished my 75 R90 including a complete carb rebuild. I have set the idle mixture and idle speed. At idle the motor purrs! The throttle seemed sluggish so I took the carb tops off and carefully reset the needles to the second notch, measuring to check they were the same.
My issue is balancing the throttle response at aprox 1500rpm. I have to take the right side out about half or more of the cable adjustment to balance. The left side is screwed all the way in. The bike seems to run and accelerate done this way but it seems odd I need to take the right out so far. Anyone have any thoughts or ideas?
Thanks in advance.
John
Victoria BC

 

[Visian]

Do you have the Bing Manual? It is pretty helpful, if not somewhat poorly written.

From what I read, you're supposed to:

- set the right side adjuster until the cable is slack with 1/32" of play when the throttle is closed.

- Then adjust the idle jet screws (the manual is somewhat unclear, they talk about the width of a screwdriver instead of how many turns out from seated).

- Then start the motor, adjust the left-side cable adjuster using a balancing tool.

- Then turn in the idle jet adjusters in until the engine nearly stalls. (creates a lean condition)

- Then go for a ride and fiddle with your idle jet adjusters to get rid of any lean hesitation as the carbs transition from the idle circuit to the main jet.

- Then set your idle speed screws to get the engine idling at the speed you want.

(Get the manual, I am doing a terrible job here).

The idea is to get the bike idling smoothly with as lean a mixture as possible, to minimize fuel waste.

Are you sure your idle jets and circuits are clear? (does the engine hesitate when you increase revs off idle when riding)

Are you using a TwinMax (or other balancing tool)....

I am going through much of this same problem on my refurbed R80G/SPD... but I have a non-stock setup (R100 cylinders, 40mm carbs... and the left side "stock" throttle cable appears too short) and I can't seem to tune out a lean-hesitation issue. My carbs were sitting for two years (float bowls drained) and I am beginning to think my idle circuit(s) may be clogged. If I can't get this straightened out after a tank or two with fuel conditioner (Berryman's was recommended to me) I am going to have a friend with an ultrasonic cleaner.

Hope some of this helps. I am going to start from the beginning on my bike after re-torque of the heads and adjusting the valves.

Ian