Topic: CB500 initial carb settings?

[puppytrax]

OK; I've cleaned out my carbs, and reassembled them. Float height set at 22mm as per the manual.

How about the air screw opening? They were set at ~1 3/4 turns out before cleaning. The manual says 1 + or - 1/8. I've read in a thread here 2 turns. This is just to get it running; which is closest/safest??

Slide opening. I've read here how to get an approximate sync using a drill bit...but what size drill bit?? I'd hate to have an idle way too high and have to try loosening, screwing, tightening, etc...all 4 carbs on the bike...while it roars merrily away at a zillion RPMs...     I'd like to get a nice low sync and then increase it with the idle screw on the rack...

Thankyouverymuch!   

1972 CB500 w/627A carbs

[TwoTired]

If your bike has stock exhaust and air filter, use the stock air screw settings from the manual.

Doesn't matter what size drill bit.  In fact, you don't need one at all.  You can avoid the risk of tool marking slides and carb bore with the following procedure:

Look through the carb bore with a strong light on the other side.  Back off the idle stop screw until you find the first slide to cut off the light.  Actually, it doesn't matter which one you pick just find a setting on your favorite where the light JUST cuts off.

Leave the idle stop setting alone for the rest of the slide adjustmment.  You can work the throtte any time, but leave the idle stop screw alone.   Pick another carb and adjust the SLIDE HEIGHT ADJUSTER to where the light just cuts off on that one.  Lock it down and work the throttle so you can see they both cut off light at the same throttle position.  Do the last two carbs the same way.  The slides are now all at equal height with each other and bench synced.

Now you can give the idle knob enough twist so that all the slides are at about 1/16 inch open. This is an approximate idle setting that you can fine tune after the engine is running.

Cheers,

[Dennis]

Doesn't matter what size drill bit.  In fact, you don't need one at all.  You can avoid the risk of tool marking slides and carb bore with the following procedure:

Look through the carb bore with a strong light on the other side.  Back off the idle stop screw until you find the first slide to cut off the light. 

Interesting variation on bench synching. Never thought to do it that way.
I like it.

Thanks Lloyd     

[puppytrax]

Interesting variation on bench synching. Never thought to do it that way.

Me neither...Thank You, TwoTired!   

[puppytrax]

I bench-sync'ed my 627A's today with TwoTired's light method...I ended up with one adjuster showing one thread; two adjusters showing two threads; and the last adjuster showing four threads...(when finished and snugged back down)...

Didn't look right to me...took the four thread adjuster off again, cleaned it again, reinstalled...still four threads showing...

Gotta go with it, I guess...   

Set the air jets at 1 1/8...then set the idle screw [on rack] at ~1/16" showing under slide...

Re-installed on bike...new insulators, cleaned manifolds, good booties...new filter...no fuel line... 

But it's slowly getting there...