Throttle cable/idle adjustment vm34

[Noidea]

Hey all been a while since i posted on here but ive been around reading old threads finding answers through other people problems for the most part. Now I got my own set of questions that I haven’t found in other threads. (Please link me to others if I overlooked them)
Ive got a 73 motor Hughes CDI kit with Vm34s at “baseline”spec
180 Main
22.5pilot
22mm float height
Middle slot on needle
Air jet removed
Unibpod filters
Pandonium ya mama exhaust

Main question I have is should my top throttle adjustment be screwed out this much to maintain idle at 1200?

I see in the carb guide theres a section on cable adjustment Stating
“Bear in mind that the carb-top cable adjustors are used to set lift synch; if they must be turned out to eliminate cable slack, the cable assembly is too long.”
It won’t really idle without throttle unless i have it at this setting. On the cable itself the adjuster is also maxxed out. Can someone send the thread the grizld speaks about in the guide using a cable adjuster to take up slack?

My throttle stop screws obviously don’t do much in this situation since the slide is set higher than the stop screw can go which makes me wonder if I’m cheating my idle. Ive read and continue to reread the carb guides both bs version and vm as well as the sudco guides. Didnt see much there fir it besides that those screws are for throttle sync. It does run ok i still need to tune it properly justworkin on a proper idle as i should.

Alsooooo anybody have any ideas of way to use this empty space seeing as I’m not running points or a mechanical advance anymore?

 

[jpdevol]

You're describing a condition with too much cable length. It was suggested to find a cable with less travel between the inner cable and the outer sheath. I have vague memory of Grizld1 also recommending a longer cable adjuster (perhaps one with a bend) to take-up additional slack -perhaps similar to this listing for a VM cable adjuster: https://www.partsgiant.com/p354057-sudco-carburetor-cable-adjuster-assembly-elbows

 

[5twins]

Something is not right with your carbs if you can't set the idle speed with the idle speed adjuster screws on the sides of the carbs. They should work even if your cables are too long. The tapered tip of the screw works against an angled slot in the side of the slide, raising the slide (and the idle speed) the more you screw it in.

 

[Noidea]

What would it be? I cant think of what would cause that issue. Because the screws on top are turned out the slides dont sit on the stop screws. Before this set up i tried every range of jetting all the way down to 17.5 pilot and 165 main to 25 pilot and 185 main and in between. The only way id get an idle in all ranges was the have the throttle turned slightly to lift the slides about that high up.
I can also try the cable adjuster suggested by @jpdevol but if the lift is too high than id be putting bandaids on the problem.

 

[AUTOMAN]

Seems like pilot circuit is zilch.
Need to jack up slides to idle is just starting the pick up transition CA circuit.

Screw the screw, how high are the slides at "idle"?

cliff

 

[Noidea]

Ive been measuring the slide from the side that the carb attaches to the engine but when trying to phrase what sideI was measuring for this message I looked at carb guide and it says measure from air intake side. Does that mean the side with the filter or the side at the intake manifold? Regardless from the side with the intake manifold I fit a 1/4 smooth side drill bit in there. The side with the filter is about 5/32 which is what the guide mentions.

 

[Noidea]

And what Circuit is the CA circuit?

 

[Noidea]

My caliper was off had edit the drill bit sizes

 

[Kevin Werner]

I have just muddled through this scenario. My process was to screw the carb top adjusters all the way in. Back the idle adjust screws in the carb bodies all the way out. Take most of the cable slack out of the throttle cable at the handle bar adjustment. Now, start the engine and screw the idle adjust in on both carbs equally (mostly) until the motor will idle. As it warms you may need to reduce the idle setting on each side equally. You can be crude here, approximately 1/8, 1/8, 1/8 each side until you have your 1000-1200 rpm idle. Now connect a manometer and adjust your idle speed screws until each cylinder is pulling equal vacuum. Now you have a nice idleing bike. Twist the throttle gently watching your manometers. Surprise. One cylinder pulls harder than the other. This is where you adjust your carb top adjuster screws. Screw one or the other out until both carbs are even as you roll the throttle on.
Now, go back and check your manometer at idle and adjust if neccessary. Now you know that the idle slide position is "sync'd" and your cables pull the slides equally.
Now readjust your handle bar throttle cable slack adjuster to remove all or most of the remaining slack.
Chech you manometer again.
It is a simple process when you are able to see the results on a manometer. There are several member here who have built thier own manometers with $5 worth of parts. Search is your friend here.

 

[AUTOMAN]

CA=Cut Away(how rich/lean the off idle pickup point is.

 

[Noidea]

So ive tried @Kevin Werner advice no change in my situation i bought those angled cable adjusters that @jpdevol mentioned those are too long and cause the slides to be lifted way too high. Ive cheked over my timing it fires on the fire mark when i get it to idle. Adjusted my valves and cam chain
Set plug gap to .040 as suggested in hhb guide reset float height as well as jetting. Still getting same result of pilot circuit not functioning properly. I messaged pandemonium on instagram about the exhaust and asked his jetting he mentioned this
25 polit 175/185 main
2.5 slides
1 to 1.5 turns on air screw
P-6 needle middle clip

I have 2.0 slides would it make my compromise that much different??
Im currently at the highest pilot I have which is 32.5. I ordered higher sizes a couple days ago to see if maybe i just need to up my jets way more. But if that doesn’t work im totally out of options tried everything multiple times. Still goin for it. Any helps appreciated

 

[Kevin Werner]

So ive tried @Kevin Werner advice no change in my situation i bought those angled cable adjusters that @jpdevol mentioned those are too long and cause the slides to be lifted way too high. Ive cheked over my timing it fires on the fire mark when i get it to idle. Adjusted my valves and cam chain
Set plug gap to .040 as suggested in hhb guide reset float height as well as jetting. Still getting same result of pilot circuit not functioning properly. I messaged pandemonium on instagram about the exhaust and asked his jetting he mentioned this
25 polit 175/185 main
2.5 slides
1 to 1.5 turns on air screw
P-6 needle middle clip

I have 2.0 slides would it make my compromise that much different??
Im currently at the highest pilot I have which is 32.5. I ordered higher sizes a couple days ago to see if maybe i just need to up my jets way more. But if that doesn’t work im totally out of options tried everything multiple times. Still goin for it. Any helps appreciated

Double check that your throttle cable is riding in the "groove" of your twist grip.
132.5 is a "lot" of pilot jet. I am at 20 with 190 mains , stock motor, VMs, pods, slightly open commando muffs.
You should be able to adjust the slack. If not you need to add spacers or get a better fitting cable. Cheers

 

[AUTOMAN]

Pilot circuit completely non-op
You are forcing the throttle open enough for the "off-idle" cut-away/needle jet fuel to flow, just to idle!

cliff

 

[Noidea]

Pilot circuit completely non-op
You are forcing the throttle open enough for the "off-idle" cut-away/needle jet fuel to flow, just to idle!

cliff

Yes thats what i figured. Whats the solution? I cleaned the circuit out multiple times. Sprayed carb clean and compressed air through the circuit and jet Same result.

Double check that your throttle cable is riding in the "groove" of your twist grip.
132.5 is a "lot" of pilot jet. I am at 20 with 190 mains , stock motor, VMs, pods, slightly open commando muffs.
You should be able to adjust the slack. If not you need to add spacers or get a better fitting cable. Cheers

Ive been adjusting slack with the adjuster on the cable. If I add spacers wont it still make my slide rise past the point of the pilot? Where would I add a spacer anyway? Between the male and female end of the adjuster?

 

[AUTOMAN]

Forget the cable adjust
Concentrate on idle, you are confusing us and yourself.

cliff

 

[Noidea]

All ive been doing is trying to focus on the idle. I asked for solutions and noones got any. So i inquire about the suggestions being made.
Nobody answered what they think about the slide situation and getting a 2.5 so i ordered them see if that works. Dont think it would though from this thread though it seems would only lean it out with a bigger opening.

Go here: www.amckayltd.com/vm34-36.pdf. A 2.5 or 2.0 slide both will work fine in a VM34 on an XS650 , you just need to select a richer pilot jet with the 2.5; from sea level to 800 feet or so, usually 22.5 or 25. You'll find more by clicking the Tech button at the top of the page.

Im just trying to consider everything because it feels like nothing is working. Dont mistake that for confusion. Im Just trying to do what i can with what I have

 

[Noidea]

https://www.xs650.com/threads/vm34.61522/

This was where I got that quote the only thread i really saw talking about slide cutaway size.

 

[Noidea]

I received the 2.5 slide and that was the answer I needed.Running that 2.0 the curve in the slide was way to shallow and didnt allow my engine to run without the throttle bieng opened up . The height that the 2.5 slides arc is cut to makes it a lot more open than the 2.0 even when the idle screw isnt screwed in all the way theres space for the engine to breath and I can finally use the carb how its intended to be used turning the mix screws have an effect as they should and the idle mix screws work properly.

Im surprised that the only thread I saw on slides was that one and that i posted not much info on them from what i saw in the grand scheme. But that did it thanks for all of you that had an input I appreciate the effort. Now down the worm Hole of tuning!!

 

[AUTOMAN]

Nothing to do with idle.

 

[Noidea]

Ok care to explain instead of leaving a cryptic message with measurements? Thought the point of this whole forum was to educate and inform people on these machines. Your not providing any insight. Just leave a sentence response and expect me to read your riddle. Apparently it does have to do with idle if it completely changes my idle situation.