shimming carb question

[tlepac]

Is this something you do only with CV carbs or does it relate also to VM Carbs? I am having a hesitation between 4 and 5000 rpm on the bike and am wondering if this may relate to my problem. I am also changing out all of the vacuum tubing with new to see if this makes a difference. (As far as I can tell the vacuum tubing to my petcock and the breather hose is original with the bike so I am changing that out for new just on general principles) My problem does seem to be getting a bit better as I ride it more but the bike is still very cold blooded and I havent been able to get the idle down to 1100 to 1250 yet on my 79 GS 750L in addition to the above problems. It has new O rings, valve shims done and new petcock from Z1---Old one was shot.

I have not done recent plug chops but the plugs when I pull them are tannish to slightly white.

Thanks for any thoughts

 

[Guest]

VMs should have notches in the needle for adjustmenst so no need to shim.

 

[Detroit Diesel Man]

VMs should have notches in the needle for adjustmenst so no need to shim.

True that VM's have notches for the needle but with mine I went one notch down to richen it and wasnt quite enough and a whole notch seemed a bit much...so I used feeler gauge material and made 4 "shims" and used those under the needle clip to get between the 2 notches..


DDM

 

[Guest]

I use washers for 1/2 notches.

 

[tlepac]

Do you guys think this will help the cold bloodedness as well? I have to run the bike with the choke on at 3/4 to 1/2 for about five minutes before the throttle will work. Prior to that it bogs down and wants to die if I try to throttle at all. But once the throttle works then I am able to get going and within 10 minutes it acts more normal, although I dont seem to be getting the acceleration that I think I should be getting.

Thanks

 

[Steve]

Adjusting your needles will help with operation on the road.

To help with your "cold-bloodedness", turn the pilot fuel screw (the one on the bottom of the carb) out about 1/8 turn. You will have to also re-adjust the air screw on the side of the carb for proper mixture, but adding a bit of fuel to the pilot will help considerably.

.

 

[tlepac]

Thanks Steve

I will try that and see what I get