MKIII Carb Sticks balancing attempt FAIL / Suggestions?

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Tinkerbell

Tinkerbell

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Hi All,
I bought a set of the Motion Pro carb sticks vacuum balancing tool. I attempted to use it on my Norton. BUT the bike was a mess without the balancing tube in place between the manifolds. I can't see how I am going to fine tune anything under those circumstances. I am considering making a special balancing tube with a restriction in it , such that the bike gets some balance, but still can generate enough of an independent vacuum signal to give useful indication on the carb balance tool ... Any experience here?
Very Sincerely,
Kara
 
Tinkerbell said:
Hi All,
I bought a set of the Motion Pro carb sticks vacuum balancing tool. I attempted to use it on my Norton. BUT the bike was a mess without the balancing tube in place between the manifolds. I can't see how I am going to fine tune anything under those circumstances. I am considering making a special balancing tube with a restriction in it , such that the bike gets some balance, but still can generate enough of an independent vacuum signal to give useful indication on the carb balance tool ... Any experience here?
Very Sincerely,
Kara
Click to expand...
All the better quality vac gauges have a dampening adjuster fitted, it's very difficult indeed to tune single cylinders without one.
 
Tinkerbell said:
I attempted to use it on my Norton. BUT the bike was a mess without the balancing tube in place between the manifolds. I can't see how I am going to fine tune anything under those circumstances.
Click to expand...


It might help if you gave a description instead of saying the bike was "a mess".

Tinkerbell said:
I am considering making a special balancing tube with a restriction in it , such that the bike gets some balance,
Click to expand...

Again, I'm not entirely sure what the problem is. Presumably, you mean a lack of damping? The usual answer is to add a restriction to each gauge line, however, if it is the type in the link below, then it comes with restrictors but I don't know how they are supposed to fit.

SyncPro™ Carb Tuner - Motion Pro

Motion Pro - High quality cables, tools and controls for motorcycles, ATVs, snowmobiles and personal watercraft.
www.motionpro.com www.motionpro.com

Restrictor Jets for SyncPro™, Set of 4 - Motion Pro

Motion Pro - High quality cables, tools and controls for motorcycles, ATVs, snowmobiles and personal watercraft.
www.motionpro.com www.motionpro.com


Tinkerbell said:
but still can generate enough of an independent vacuum signal to give useful indication on the carb balance tool ... Any experience here?
Click to expand...

Amals don't seem to generate much vacuum so some balancer readings can be low enough to be almost off the bottom of the scale.

I have a Morgan Carbtune which I connect to the balance tube inlet stubs so that works fine with the balance tube removed although it has to be hung in the inverted position to get good low vacuum readings and this is mentioned in the instructions. The tubes have restrictors to damp the pulses.
 
Tinkerbell said:
Hi All,
I bought a set of the Motion Pro carb sticks vacuum balancing tool. I attempted to use it on my Norton. BUT the bike was a mess without the balancing tube in place between the manifolds. I can't see how I am going to fine tune anything under those circumstances. I am considering making a special balancing tube with a restriction in it , such that the bike gets some balance, but still can generate enough of an independent vacuum signal to give useful indication on the carb balance tool ... Any experience here?
Very Sincerely,
Kara
Click to expand...
The balance tube's primary job is to keep vacuum at lower RPMs so that pilot circuit remains full of fuel. If you sealed both balance tube connections, the bike should run fine but not idle as well. British twins were around a long time before balance tubes were added. If the balance tubes are open to the air, you'll be very lean, especially at idle.

If you're trying to balance the carbs at or near idle - don't use a vacuum tool - follow the workshop manual instructions. Or, PM me and I'll tell you how I do it - I don't want to start a war here.
 
"If you're trying to balance the carbs at or near idle - don't use a vacuum tool - follow the workshop manual instructions."

Actually follow the Norton instructions? :eek:

If folks did that we wouldn't have all the great solutions for the problems that have been invented over the years! ;)
 
Hi All,
Let me clarify. The bike was running very nicely and idles nicely with the balance tube in place. I wanted to use the sync tool to see how well I did with my mechanical setup and mechanical sync technique. WHEN I installed the sync tool to the manifold ports, the bike ran really rough and crappy and did not want to idle. I could not see any leaks in my setup. The conclusion I came to was that the 850 really likes its balance tube. I theorized that I could construct a balance tube with a restriction in it that would do two things: first it would still allow the bike to run decently, but allow a measure of independent vacuum signal from each port that would still be usefully measurable on the sync tool. My inquiry was seeking others' experience with sync tools of this type.
Thank You!
Kara
 
Tinkerbell said:
Hi All,
Let me clarify. The bike was running very nicely and idles nicely with the balance tube in place. I wanted to use the sync tool to see how well I did with my mechanical setup and mechanical sync technique. WHEN I installed the sync tool to the manifold ports, the bike ran really rough and crappy and did not want to idle. I could not see any leaks in my setup. The conclusion I came to was that the 850 really likes its balance tube. I theorized that I could construct a balance tube with a restriction in it that would do two things: first it would still allow the bike to run decently, but allow a measure of independent vacuum signal from each port that would still be usefully measurable on the sync tool. My inquiry was seeking others' experience with sync tools of this type.
Thank You!
Kara
Click to expand...
I've never needed to do that with a commando
But there is no reason I can see why your idea wouldn't work
Incase you haven't done this before make sure you get the carbs balanced on the idle adjusters
Then micro adjust the cables to get the vacuum the same as as the slides lift off of the adjusters
Also cable tying the the cable splitter to frame helps to keep the carbs in balance
Cheers
 
Tinkerbell said:
WHEN I installed the sync tool to the manifold ports, the bike ran really rough and crappy and did not want to idle. I could not see any leaks in my setup. The conclusion I came to was that the 850 really likes its balance tube.
Click to expand...

The balance tube doesn't make that much difference. Repeat your test with the manifold spigots capped to confirm. Any auto parts store will have rubber caps for vacuum lines.
 
Shouldn't be drawing air when hooked to the carbs sticks. That should be only thing that would cause your bike to run poorly when checking.
 
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