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3,989 Posts
Discussion Starter #1
Just got to the setting/balancing the carbs part again.
Got the notes from JBA, Haynes manual, and Amal.
So the sliders disappear on full throttle, and they`re synchronized.
JBA says put a 3/16" drill under the sliders or an appropriate size for the cutaway.
3/16ths is the standard size of #3 sliders (6/32"), but mine are #3 1/2...7/32".
"Screw in the throttle stops on each carb until the drills lust begin to dip...find a `sweet spot`.
OK the sliders are just resting on the throttle-stop screws.
I am able to adjust for faster revs but not slower,
because the sliders screws are at minimum.
"slowly open the throttle until both dip at exactly the same time by adjusting the cable adjusters". Done!
"Start the bike, it will likely idle too high, wait for the engine to wam up, (not done yet)
then adjust each throttle screw down (out) by EXACTLY the same amount..."
NO Adjustment!!!
May I make a suggestion?
Use the next size up drill for setting up.
In my case, for 3 1/2 sliders (7/32 5.5mm) use 6mm drills.
This will give 0.5mm of adjustment for slower tick-over.
Incidentally, Haynes takes a different view..."screw the throttle stop screws fully in and adjust for slow running".
Something not quite right for both of these methods.
Maybe the first method with the drills should read "Find the spot where the drill begins to dip, and turn the throttle-stop screw IN half a turn...or whatever).
Repeat for both carbs.
Any comments?

1,547 Posts
Hi Caulky, :)
here's my third way just to confuse things a bit more ;)

I have never been one for sticking things in me carbs, apart from my fingers.
Tickover problems can be poor cable adjustments.
I start off by slackening all three cable adjusters,
then slacken or remove the tick over screws so slides a as far down as they can go.
Pull both slides up with the cables, this pulls the splitter bit too the carb end,
let the cables return, then take up the slack with the two adjusters nearest carb’s, leave an equal 1/8” slack in both cables.
(An 1/8” is a bit big you are aiming for around a 1/16”)
Judged by lightly pulling on the outer cable near the carb top and adjusting until an 1/8” gap is achieved for both cables.
Then twist the throttle to be nearly flat out, shove your finger in the carb and feel for the slide, note its position,
then with out moving throttle, move you finger to the other carb and feel for the slide
if it hangs down further you should tighten it’s adjuster a touch,
if the slide is not there, you should tighten the other carbs adjuster a touch.
Repeat this process until both slides hang down the same amount and you still have approx 1/16” slack on BOTH cables when slides are closed.
Screw the tickover screws back into carbs, as you turn feel the slide for movement,
just as it moves stop turning and repeat on other carb.
Then adjust the adjuster near the throttle leaving 1/16” slack in that one.
The cables should now be set, all other adjustments after they are, should be on the carb air screws and tickover screws.

About 8mins into this is the finger trick.

3,989 Posts
Discussion Starter #3
Thanks Plewsy,
Nice video!
I`ve actually set them up using 6mm drills, which gives 1 turn...ish of low end throttle screw adjustment.
If it over-revs and I`m unable to adjust it out, I`ll try again with your method.
Initially I`m looking for nice even tick-over at about 800rpm or so.
Also I have been dogged with smokey, rich mixture, wet oily plugs, etc., which couldn`t be tweaked out.
This was the reason for the head refurbishment.
But that also called for the change of slider (leaner) and a smaller main jet (leaner), and iridium plugs.
Wondering if I should use the middle needle notch, its in the lower notch at the moment. (richest)
How it will run after these mods, I have no idea.
If it runs nicely and the carbs are adjustable...I will fit long velocity stacks (with gauze), and dispense with those awful air-boxes.
I think whoever designed those, bought his qualifications from tesco.:rolleyes:
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