Twinstar Carb Question

[Slacker]

Picked up a 78 Honda CM185 beater bike for Momma to learn on. The carb had been overhauled in more recent times. The problem is that the return on it is slow. The engine wants to stay at a medium rpm for a few seconds after returning the throttle to idle position. If I rap the rpms up, when the engine is staying at mid rpms, then the engine will return to idle quickly.

I have the throttle cable relaxed, so it shouldn't be the problem. I'm thinking weak return spring at the top of the carb. Anyone know if I'm on the right track? I have overly Seafoamed the thing.

 

[satariel666]

Picked up a 78 Honda CM185 beater bike for Momma to learn on. The carb had been overhauled in more recent times. The problem is that the return on it is slow. The engine wants to stay at a medium rpm for a few seconds after returning the throttle to idle position. If I rap the rpms up, when the engine is staying at mid rpms, then the engine will return to idle quickly.

I have the throttle cable relaxed, so it shouldn't be the problem. I'm thinking weak return spring at the top of the carb. Anyone know if I'm on the right track? I have overly Seafoamed the thing.

Most of the time its bad spark plug if that things happens.

 

[Slacker]

I did change the plugs this morning. Thanks, though.

 

[naughtyG]

I had the exact same problem on my ex's CM200T.

Open the top of the carb, and pull out the throttle with its spring and cable. On the side of the throttle, you will see a groove, and inside the carb body, there is a pin that goes into that groove (stops the throttle from spinning).

Basically both the pin and groove get gummed up over time, and stop the throttle from sliding back down freely. You need to clean the hell out of both, maybe even use 2000 or 1500 wet n dry sandpaper in order to remove the hard residue.

I found that polishing the throttle to a shine also helped a little, but it never went away until that pin and groove were totally squeaky clean.

 

[Slacker]

Cool beans. I'll give it a go tomorrow. I had lifted the lid and sprayed some carb cleaner and a pinch if liquid wrench in it. Sounds like she needs more than that. Thanks for the info.