Carby slide height

GoldenMotor.com

rohmell

Active Member
Jun 2, 2010
1,531
6
38
New York
Hello to all on the forum!

I have just completed my first MB kit, and I would like to lower the idle. When at rest there is a gap between the bottom of the carburetor slide and the carb itself. The gap is about 1/16". I know that the idle screw adjusts the slide as to at what point it hits the ramp in the slide, but even with the idle screw completely removed, the gap is there.

All of the cable slack adjustment screws are fully homed and I have noticed this gap with I first got the kit and was playing around with the parts. The throttle and cables have been lubed and everything operates smoothly.

It looks as though the throttle cable is a wee bit too short, or the cable housing is a wee bit too long.
What I want to know is: is the slide supposed to be completely closed when at rest and the idle screw is removed? I believe so, because then the idle screw can control the slide height by use of the ramp/screw adjustment.
 
Last edited:

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
So far you are correct. If the idle speed adjusting screw is removed, the slide should close off the carburetor. I can only suggest that you take a look inside the slide bore and see if there is anything in there that would prevent the slide from having full action. If you think that there is something wrong with the length of the inner cable of the throttle control cable, you could disassemble the slide from the cable and remove the locking nut on the cable adjuster that screws into the carburetor slide cap, and reassemble it all back together. I have to ask though, how is your cable routing from the handlebar control to the carb? If there are any tight bends in it then the cable cannot slide inside the housing smoothly, and may prevent the inner wire from extending completely out of the carburetor end. Also, alot of bends will effectively consume some available length of the inner cable and reduce it's overall workable length.
Lastly, be sure that there is nothing inside the handlebar control that may be causing the twist grip to not fully rotate to the throttle closed position.
 

rohmell

Active Member
Jun 2, 2010
1,531
6
38
New York
Hi GearNut, thanks for your reply to my post.
When I first got the kit, I practiced assembling and disassembling all of the various components to familiarize myself with them, and even then, with a brand new straight throttle cable, no kinks or bends, it was always the same with that 1/16" gap. I think the gap was there even without the twist grip attached.

I thought maybe that was some sort of preset minimum slide setting, and I never experimented with the idle screw at that time.

I think I will disassemble the cable and just drop the slide in by itself and see where it goes. maybe there is some casting flash or a rough spot keeping the slide from going down all of the way.
 

rohmell

Active Member
Jun 2, 2010
1,531
6
38
New York
Success! The hex cable adjuster that screws into the carburetor slide cap did not have threads on it all the way to the end where the cable inserts into it. I threaded it to the end with a die so that it could be screwed in further and the slide almost closed fully. A little bit of filing on the throttle cable end allowed me to be able to close the slide completely. Now, the idle screw will be able to perform its intended function.