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Help with adjusting carbs

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Brandon -

Looks like everyone is on to something. Again, as I have mentioned several times in the past, the throttles on an HD carb should be fully closed at idle.

If the throttle levers are touching the throttle shaft lever (in the red circles in the picture) on the shaft between the carbs when the throttle is full off, then this means your throttles are partially open at idle. This can cause the variability you are talking about.

You need to adjust the levers such that they back off and are just slightly off from being engaged when the throttle is off.

Also, you have OEM carb air filters so you are ok there.

Finally, I notice that you have a rubber plug on the outlet for the Brake Servo on your intake manifold. Check this carfully for cracks or loose fitting, if this plug has any air leaks in it, it will cause air leaking into the manifold and cause variability in idle speed as well. You might consider putting a hose clamp on it just to be safe.
 
The butterflies are both closed completely and they open together. I've attached a picture of each closed just to make sure I'm not missing anything.

I've attached a closer picture of the throttle shaft. I'm not exactly sure what I need to do here. Can you tell anything else from the attached picture? Do I need to adjust anything?

Alan - Good call on the plug to the servo. I'll add a hose clamp to it.

PS - The air filters are pain in the a$$ to get off!! /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

Thanks!
 

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OK Brandon, looks pretty good. Except the butterfly in the rear carb may have been buggered upon installation. See the little wrinkle in it on the right hand side close to it's shaft. Further, baring a bad shadow the upper left hand edge appears to be unsymmetrical and may be leaking air.--Keoke
 
I zoomed in on it and it does look like there is a small gap in the upper left hand edge. Is there any way to fix this or is it that big of a deal where I would notice a difference?
 
Yep Brandon,Send the carbs to Joe Cutro for a proper rebuild. I also forgot to tell you, as I looked at the inboard side of the front carb's shaft the gland is missing.---Fwiw---Keoke

P.S. I can still make it run for you if you do not want to fix em up right now. Course it might burn a little more gasoline. /bcforum/images/%%GRAEMLIN_URL%%/grin.gif


---OPS! about them air cleaners wait till you go to put them back on!--- /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif
 
Well then, my next task will likely be to have them rebuilt.

However, that may be a few months off. In the meantime, what is the best quick fix?
 
Brandon -

I think Keoke is right, the rear butterfly valve is not seating properly.

You don't need to have the carbs rebuilt to fix this, all you need to do is to remove the carburettor and then loosen the two fixing screws (just loosen them, don't take them out) and then seat the butterfly flap in the fully closed position, then tighten the screws down.

This is a very common "PO" mistake with HD carbs... the butterflys have to be able to close fully otherwise the slow idle will never work correctly. With other carbs like HS or H carbs, this doesn't matter so much (because slow idle runs through the main throat on those carbs).

If you want and you are feeling up to it, I'd also get the teflon bushes from David Nock and put them on the carb throttle shaft while the carb is out of the car. If you do this be sure to get new butterfly flap screws (62 on the moss page) as well, as you will have to remove them to remove the shaft. Removing the shaft is pretty easy, as long as you have a small punch to drive out the little pins that hold the levers on the throttle shafts.

I also checked your question on which O rings to get for the slow idle screw... whether to get 50 or 51 on the moss motors page. Really all you need is the rubber piece (51) but while you are at it why don't you just get both... they're only a dollar a piece.

Hope that helps.
 
Alan - Do you think that small gap would be causing my problems? I'm in the process of ordering the parts so we'll see in a few weeks, but I wasn't sure if that would cause my issues.

PS - I found an easier/faster way to put the nuts back on the air filters. I used a telescoping magnet pickup tool to get them on most of the way. Then it took just a turn or two of a wrench to make sure they were tight. Took me hardly any time at all!
 
Brandon -

Pretty cool technique with the carbs... once you go through a process or two, the carbs are very quick and easy to remove as well. I can have them off in 15 minutes, and on in 15!

I might suggest also that you order carb to manifold gaskets (at least 2 if not 4). You run the risk of ripping the gaskets when taking the carbs off... and these gaskets are very very important for a good vacuum seal on the intake manifold.

Regarding the gap on the butterfly flap - absolutely - getting rid of this is critical for good running for an HD carb. If there is a gap, you will never be able to properly synch the carbs at slow idle and the only cheap and easy solution is Keoke's /bcforum/images/%%GRAEMLIN_URL%%/crazy.gif ...
 
Yep Alan,you are just about right.---Keoke- /bcforum/images/%%GRAEMLIN_URL%%/cowboy.gif
 
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