[kirkn]

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

 

[tbpmusic]

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..........

 

[kirkn]

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. I've only done it by sight/feel on the needle valve spring-loaded gizmo or by blowing thru the fuel inlet tube and listening for when shut-off occurs.


Thanks for all the tips.

I put my carbs on the bike last night and had 'er running, but the float valves just weren't sealing at all. I was afraid they weren't going to and took a gamble. It didn't pay off. New needle valves and seats on order...

Made it impossible to get it running / idling nice. Carbs were either flooding or starving. There was a very brief window of sweet running while the float levels were "right", but it was kind of like juggling live cats while someone behind you randomly sticks you with a pin...

 

[tbpmusic]

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.

 

[KERRY]

Set the timing first - it affect every other setting. Set the float levels on the bike with a calibrated card. You can synch the carbs mechanically, and you can do this by feeling one throttle arm with the adjustment screws turned out and watching the other one. The exhaust pulses should now be the same because both cylinders should be firing equally: if they aren't, you should look for the reason. If you take a piece of vacuum tube, stick one end in your ear and hold the other at exactly the same place next to the opening of the respective exhaust pipes it will eliminate ambient noise and differences in your position. You'll get a better idea of whether the sound is the same.

 

[kirkn]

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

 

[tbpmusic]

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..........

 

[Bird76Mojo]

Every bike I've ever stored for the winter did that when you're emptying the bowls out using that method. As it leans out it revs up. It's not necessary to do it daily, unless you only ride it once a month. For winter storage it's a must.

GB :mrgreen:

 

[GBones]

Every bike I've ever stored for the winter did that when you're emptying the bowls out using that method. As it leans out it revs up. It's not necessary to do it daily, unless you only ride it once a month. For winter storage it's a must.

GB :mrgreen:

+1 on that.
My cb450 behaves in the same way. Good to know.

 

[kirkn]

Well, most bikes I've owned do that, just not to that extent. I guess I'll not worry about it. I guess they really do lean out as the fuel level in the bowl drops.

What is this 'winter storage' you guys speak of? :lol: :lol:

I always try to shut the fuel off a half a block or so before I get home. It leaves less fuel in the bowls to evaporate away (less wasteful), and less in there to go bad in case the bike sits longer than anticipated before the next ride...

Kirk

 

[Bird76Mojo]

The opposite would be true for your fuel tank. If storing the bike leave the tank full to the filler neck to prevent condensation and then rust. A fuel additive helps keep todays crap fuels stable as well.

Additionally, I don't care about fuel evaporating as a waste issue, but more of what it turns into in the fuel bowls. Varnish goo! ARGH! :evil: When it starts to evaporate it clogs the pilot jets really easily. It is good for the float needle valves to have the bowls empty. It makes them last years longer if they're rubber or viton tipped.
.
GB :mrgreen:

 

[kirkn]

Well, for one reason and another, I'm back to checking the float levels, and here's my question:

When you measure from "the carb body" to the bottom of the brass float for the 21mm, do you measure from the lip that extends below the level of the top surface of the bowl? Or do you measure to the gasket surface "up inside" that lip?

It's a difference of a few millimeters, and the Honda manual isn't clear...

Kirk

 

[CB200]

Hi Kirkn-CB200 here I've got your problem and you may have the same issue I did. A small hand full of the very earlest CB200's used different jets than the rest. If over the years the carbs were replaced or rebuilt and the more common #38 & #88 jets were used instead of the #35 & #95 -- carb tuning is like splitting a hair. It can be done but you need to set the floats to almost the point were they bottom out before opening. Then set the needle pin for the main jet to the deepest setting. Then tune the air/fuel at idle best you can. It will then-with the fuel valve shut off, rev up just before the fuel in the carbs run out---but it will tune quite nice other than just how close the float level is to bottoming out. If you can locate the #35 idle jets and the #95 mains then it tunes normal. A crafty home craftsman can ream the #88 main jets to 95, but the idle is out of the question.
Another tune issue-- due to the stops on the slides being independently adjustable one needs to mount the carbs to the motor and look at the amount of opening of the slides at idle and match them first (via the idle speed adjustment screw) then check if they close at the same time- but you may have already figured this one.
It's lip to float bottom-but if you have that jet issue it's more like 22 to 24 and ream the main--what is your motor's serial #?

 

[66Sprint]

"It's lip to float bottom-but if you have that jet issue it's more like 22 to 24 and ream the main--"

Ok...First of all, float height is measured from the body's gasket surface (without the gasket), NOT FROM THE LIP!!!!!!!... And spec is 21mm.... (However, I do agree on the bigger main)

Secondly, according to my manuals, the 38 pilot/88 main was factory on the CB models....The 35/95 combo was used in the CL carbs.....It is possible some CB's had the CL jetting, but I can't find any reference to that in my manuals.....Personally, I'd run 38 pilots, 98 mains (like the 175's used) as I prefer a little richer jetting.....

Steve

 

[Bird76Mojo]

Kirks last post on this topic was October 2nd guys..


GB :mrgreen:

 

[kirkn]

true, true...

Meanwhile, the bike has been returned to my Mom (I guess she wants to maybe ride it again at 73 years old after all!!).

I never COULD get it to run not rich. It had the original jets from Honda (as the bike has been in my family since new) and they matched the jets that came in the rebuild kit. It seemed to run fine, but plugs were always black and sooty and it got crappy mileage - 40~42 mpg. But, it started fine, idled, carbs were synced using manometer and it had good throttle response. Weird.

But, thanks for the reply re: setting from the gasket surface rather than the lip.

Kirk

 

[CB200]

The one photo I have shows the lip but it is a poor manual. I was never able to get the carb to tune real good at early progression untill I found out about the alternative idle jet and got a set. Now that I have the jets worked out I'll try setting the float to the seat rather than the lip.
I found the alternate jetting by way of a parts supplier's parts list. According to their list the alternate jetting was only for a few of the first production run 200's--- I am interested in the manual that the drawing came from--looks better than any I've got.

 

[66Sprint]

GB.... Posting date notwithstanding, I had to offer what I believe was/is correct (and why) when advice counter to my knowledge/understanding is given......I'd hate to have a newbie accept an inaccuracy as truth, or worse, act on erroneous information and get hurt ...
..... It's part of that Moderator stuff I've been entrusted to do......
It's also part of the learning/sharing we are all in this forum for, and I learn as much or more than I could ever teach or explain.... Steve

Kirk, If you set 21mm from the lip, it should be shutting off, running out, or leaning out sooner, not overflowing.... These bikes ARE prime candidates for viton tipped shut-offs, as the brass tipped needles almost never shut completely off properly... (which I assume might be your problem).... Did you try dropping the main needle in the slide, or hotter plugs?...........

CB200, The pic is from a big (1400+ page), old, hardbound Chilton's Manual that is one of my favorite references.... I think it cost $80 back in the day.....I don't know if you could even find one now......

 

[Bird76Mojo]

The pic is from a big (1400+ page), old, hardbound Chilton's Manual that is one of my favorite references.... I think it cost $80 back in the day.....I don't know if you could even find one now......

My local library has a whole bunch of them available.. Hardcover Chiltons...


GB :mrgreen:

 

[66Sprint]

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