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Syncing the CL77 Carbs

Fuel System: Gas (Petrol) tanks, Carburators
gbyoung2
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Syncing the CL77 Carbs

Post by gbyoung2 » Sat Feb 08, 2020 5:12 pm

Curious what ya'll might be using to sync the CL's carbs?

I have one of the old Uni-Syn tools from my sports car days, and used it syncing the carbs on the Kawasaki triple 2-strokes back when the earth was still hot. I may slip off the carb-to-filter runners and see how it does.

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brewsky
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Re: Syncing the CL77 Carbs

Post by brewsky » Sun Feb 09, 2020 5:04 am

I would think a good mechanical sync should be plenty good for a twin.

I have used ball bearings to bench synch several 4's and then checked them with mercury synch tools.

Each time they were within the vacuum spec differences.

The more above idle the slide gets, the less difference it makes anyway.

I don't know if this method could be used on a scrambler, but maybe its worth a look. (drill bits are a common alternative)


https://www.bing.com/videos/search?q=ba ... &FORM=VIRE
66 dream, 78 cb750k, 02fz1, 09 wing

DJM
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Re: Syncing the CL77 Carbs

Post by DJM » Sun Feb 09, 2020 7:09 am

Just watched the video, what a brilliant and simple idea, it would only work though on carbs that you can keep bolted together when they're off the bike so wouldn't really work on a CL77.

As pointed out, for a twin, mechanical synch. should be enough, I've always used the drill bit method or similar with pieces of round bar stock.

As an additional check, open the throttle wide and check that the cutaway sections of the slides disappear at the top of the carb. throat at exactly the same time, in some respects this is better as in negates any error in throttle stop settings.

Get them both right and you should have a good smooth running set up, if not, you know it's down to balancing on the air screws.

These old carbs aren't super critical and, provided both air screws are screwed out by the same amount you should be good.

gbyoung2
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Re: Syncing the CL77 Carbs

Post by gbyoung2 » Sun Feb 09, 2020 12:44 pm

Come to find out the Uni-Syn wouldn't work anyway. The tower for the pith ball won't clear the tank's rear mounting boss for the LH carb, so some of the other means will have to do. Will say I've never heard of the ball bearing method on a set of racked carbs. I originally used the Carb-Stix, and now the Twin-Max when syncing my Concours' carbs. If the insulators were more readily available, I'd modify a couple of them and stick in port barbs to use the Twin-Max. That would be ideal.

Since I've just recently gotten my CL running, I haven't got the idle nice and smooth the way I'd like just yet. Air filters are new, timing is dead nuts, advancer is working, and valve lash is at spec. I had to increase the size of the mains to eliminate a bogging issue, so maybe I need to bump up the size of the pilots as well.

We'll keep diddling with it, and when the frustration level peaks, we'll try the pilots.

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brewsky
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Re: Syncing the CL77 Carbs

Post by brewsky » Sun Feb 09, 2020 1:13 pm

DJM wrote:
Sun Feb 09, 2020 7:09 am

……... it would only work though on carbs that you can keep bolted together when they're off the bike so wouldn't really work on a CL77.
I would be tempted to try it with the carbs mounted,...……. carefully! ......…...since the rear of the slide is lower than the front, the bearing should catch at the rear instead of falling into the intake tract if you don't open it too far. Retrieve the bearings with a small magnet on a stick?
Just thinking out loud...….
66 dream, 78 cb750k, 02fz1, 09 wing

gbyoung2
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Re: Syncing the CL77 Carbs

Post by gbyoung2 » Sun Feb 09, 2020 2:00 pm

"I would be tempted to try it with the carbs mounted,...……. carefully! "

I just felt a shiver go down my spine. :-)

Be my luck that I'd sneeze just about the time I was carefully cracking the throttle. Now, if the choke slides were on the other side of the throttle slides, maybe.

LOUD MOUSE
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Re: Syncing the CL77 Carbs

Post by LOUD MOUSE » Sun Feb 09, 2020 2:48 pm

Visit the FAQ area and go to "How I Tune My Engine. ........................lm

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