CB200 Carb Sync & Float Level Tips?

19293 Views 21 Replies 7 Participants Last post by 66Sprint, Dec 16, 2009

kirkn

Discussion Starter · Jun 10, 2009

OK, how 'bout listing up your favorite methods for syncing the carbs on a CB200 (independent slides) and for setting / checking the float levels.

I've had to completely disassemble, clean and soak the carbs on my '74 CB200 - standard rebuild technique. My synchronizing style is to bench-sync them first, just by eyeballing the gaps beneath the throttle slide and trying to make 'em the same. But, I have no idea where this will leave the idle speed setting.

Next, though, is connecting the two separate cables to the slides and trying to set free play. Here, I just try to sync them so that I can just hear the slight "click" the slides make as they close and try and get 'em together. But, my ears aren't as good as they once were...

But this is kinda crude. Anyone got any better suggestions? Anyone drilled & tapped the manifolds for using a mercury-type carb synchronizer?

How 'bout setting float level on these? Anyone fabbed a screw to thread into the bowl drain and connect a clear tube to check actual level? I guess I should start with the manual, to see what it actually says about setting float level...

Thanks for any tips and techniques.

Kirk

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tbpmusic

· #2 · Jun 10, 2009

You have to pull off the air filters, then back the idle speed screws out till they have no effect.
I use the pinky of one finger to lightly touch one slide while actually watching the other slide.
It's very akward to do. Use the adjusters at the end of the cable (on top of the carb) to make the slides both move at the same time.
Later CB200's had vacuum taps as stock, you might look around for a pair of manifolds.
It would make things way easier.

Then get it to idle, set the mixture screws, and "balance" them by feeling the exhaust pressure, like you would with a 350 or 450.

I always set floats off-bike, using real gas.
Can make a little mess, but works for sure.

Throttle cable routing is absolutely critical on CB200.
There's barely enough cable to reach, and if you don't get it right, it will give unpleasant surprises when you put the tank on..........

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tbpmusic

· #4 · Jun 10, 2009

kirkn said:
Cool. Thanks for the tips re: sync-ing. Your way looks at when the slides first lift off. Mine "listens" for when they both seat back down. Interesting.

Hmmm.... never done anything by feeling exhaust pulses. What do you feel? Can you really tell something by that? You must, or you wouldn't've mentioned it... How does it behave when they're in sync vs. not in sync?

As for float setting and real gas, do you mean looking for when the liquid flow actually starts and stops? That's a good idea.

Getting the slides to move at the same time is the "synching" part.
I don't hear well enough to use your method.
With vacuum taps, you just use the adjuster at the throttle grip to get it running about 3,500 rpm - then use the adjusters to make them even on the gauges.
Restore the throttle grip adjuster, then do the same balancing act with the idle scews (at idle, and after doing the mixture screws).

"Balancing" is the part where you feel the pulses - read the 450 link, it's all the same for you except the part about the throttle flippers. http://www.hondatwins.net/forum/viewtopic.php?f=29&t=537
You're feeling the relative pressure of the exhaust - it's half art......
Once again, vacuum taps make it easy to do this.

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tbpmusic

· #7 · Jun 17, 2009

kirkn said:
OK, thanks, all. Got the float levels set at 20 ~ 21mm using the on-the-bike-with-gasoline method. Worked very well. Also followed Bill's sync advise and mixture screw setting. Set the point gap and timing per the shop manual using test light before any of it.

All in all, it idles nicely and has clean, snappy throttle response.

BUT, when I shut off the gas and let the engine run the bowls empty, it revs up quite a bit as they empty out. I've heard that float level is really important, but I've never had one climb so much as they empty out. Maybe up to 3500 rpm or so.

Does this all sound normal? As soon as I turn the gas back on and the bowls fill, the rpms come right back down and it idles just fine. Seems weird to me, but as long as it all seems OK otherwise, I think I'm just going to run 'er that way.

Kirk

I have no idea what to say about that - very strange indeed.
But as long as it runs well..........

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tbpmusic

· #21 · Dec 16, 2009

66Sprint said:
Excellent point GB!....... In these days of instant electronic access to lots of information, we often forget these repositories of knowledge..........

Sadly, if I depend on Chiltons, it's usually more like a "suppository" than "repository"........... :shock:

:? :?

What ?....

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