Topic: Fast idle cam (choke plate adjustment)?

[denward17]

I just rebuilt my carbs (78 CB750K --- PD42A).

After getting the carbs re-assembled when I pull up the choke lever by hand, the choke plates will not move.

Not sure if I put them together correctly or not, but I think I did after searching and reading many threads here.

Is there any information available to adjust the fast idle cam?

I'm not sure where to find a service manual that would explain this how to.

Thanks
Dennis

[stocky]

Take the choke plates back off and try and see if the choke rod will move freely through the carbs when you pull the choke lever, lotta times the choke plates are installed back and not aligned, so it’ll catch on the side of the carb wall.

[denward17]

Take the choke plates back off and try and see if the choke rod will move freely through the carbs when you pull the choke lever, lotta times the choke plates are installed back and not aligned, so it’ll catch on the side of the carb wall.

Thanks stocky,
I loosened the screws/bolts on the throttle back plates and now they move freely.

I read in a thread last night (doing a lot searches here, very helpful) to make sure when you tighten the backing plates that the carbs are on a solid level surface, and my work bench had a piece of carpet under the carbs, but I think I may have worked half way on and off of that carpet.

[denward17]

After I put the front plate and rear plate back on, I loosened all the choke plate screws and aligned the plates, then tighten them back up, all is good now.

Also found the adjustment procedure for the fast idle cam.  I will wait and check this after the carbs are re-installed on the engine with the choke cable connected.

[stocky]

It’s been awhile but I think you can check if the fast cam idle is working before putting the carbs back on, just hold the choke open fully and visually see if the slides are opening slightly more. If it does then that should be good enough and should work fine when carbs are back on as long as the cable and everything else is adjusted properly. Should also be visually checked once they’re mounted and cable is hooked up.

[denward17]

It’s been awhile but I think you can check if the fast cam idle is working before putting the carbs back on, just hold the choke open fully and visually see if the slides are opening slightly more. If it does then that should be good enough and should work fine when carbs are back on as long as the cable and everything else is adjusted properly. Should also be visually checked once they’re mounted and cable is hooked up.

Indeed, Thanks for that.  I went and looked at, the procedure calls for closing the choke, with the fast idle cam just barely touching, then let go of choke and turning adjustment in 2 1/2 turns.
After that adjustment, and fulling closing the choke again, I can see the throttle slides open up just a wee bit.

And to update, my carbs are PD42B, not A.

[Airborne 82nd]

You can build a carb jig and set up the carbs on the bench.