Author Topic: How to achieve float of 21mm for my cb350f carbs (Read 5703 times)

yd72 · « **on:** July 20, 2007, 08:39:28 AM »

Can any kind heart soul in this forum show me in photographs and clear explaination on how to adjust my cb350f carbs float.

I have seen the manual and some posting on how to adjust the float, but still I am not very sure whether I have done it correctly anot.

Can anybody help me?

Jugghead · « **Reply #1 on:** July 20, 2007, 09:15:33 AM »

When I disassembled/rebuilt a set of 350F carbs, this photo tutorial was tons of help:
http://www.salocal.com/sohc/tech/carb/carbpg2.htm
http://www.salocal.com/sohc/tech/carb/asmpg_mgs/adjsttang.htm
Good luck to you!

crazypj · « **Reply #2 on:** July 20, 2007, 09:15:44 AM »

Tilt carb body so float arm just touches shut off valve (Honda say about 60~80 degrees) If its completely inverted as shown in manual its going to be closer to 26mm when fitted.
In link above, second and third pics show correct angle
PJ

kslrr · « **Reply #3 on:** July 20, 2007, 11:59:36 AM »

To make the job easier, I check float hights after the carbs are fully assembled (less the float bowls) as well as the whole carberator/throttle linkage assembly complete (would not work for older 750's though). I then put the assembly in my bench vise at the proper angel for float hight messurement.

super pasty white guy · « **Reply #4 on:** July 20, 2007, 01:09:10 PM »

A question: What is the reason for the angle of the carb bank when checking? I've understood that it's so the float doesn't compress the spring in the valve. Is that right?

If so, wouldn't it be really easy to just take a valve (or whatever they're called) and glue/solder it so that the spring can't compress?

Just wondering.

Dave

kslrr · « **Reply #5 on:** July 20, 2007, 02:17:14 PM »

Interesting idea Dave. Insert that one 'test' float valve, set the hight and then replace 'operational' float valve for each carb? Sounds like it would take more time and would not result in more accurate hight settings.

IMHO.

yd72 · « **Reply #6 on:** July 20, 2007, 07:10:47 PM »

Thanks guys for all the help. Let me try it out.
Should the float be almost parallel to the gasket surface of the bowl?
After dismantling the float I notice that all the float are all measure at 30mm over and tilting at 60 degree.

I was think did mine mechanics set the float correctly when he was servicing my bike? It was so different from the specification of 21mm.

What will happen if the float is not set correctly? Pls enlighten me.

: )

super pasty white guy · « **Reply #7 on:** July 20, 2007, 07:20:52 PM »

Yeah, except that you could probably do this on the bike. I'm a big fan of leaving the things on the bike.

Dave

Quote from: kslrr on July 20, 2007, 02:17:14 PM

Interesting idea Dave. Insert that one 'test' float valve, set the hight and then replace 'operational' float valve for each carb? Sounds like it would take more time and would not result in more accurate hight settings.

IMHO.

Jugghead · « **Reply #8 on:** July 20, 2007, 07:22:30 PM »

Two things can happen.
at one end of the spectrum, your floats will let too much gas into the carb bowls before turning off/tripping the valve closed and you will have gas leaking out of your overflow tubes.
on the other end of the spectrum the floats will close the fuel valve before the bowls fill completely, and at high vaccuum/wide open throttle, there won't be enough gas in there and you get overly lean running conditions/loss of power due to fuel starvation.

yd72 · « **Reply #9 on:** July 20, 2007, 08:54:25 PM »

I still don't understand, I have adjusted one of the float to 21mm and inverted the carbs so that all the floats drop in gravite. I noticed that two of the un-adjusted float are actually the same level as the one that I had just adjusted.
So strange! I am puzzled? Why is it so?

crazypj · « **Reply #10 on:** July 23, 2007, 06:29:06 AM »

You don't have the floats in upside down do you?
PJ

yd72 · « **Reply #11 on:** July 25, 2007, 08:31:12 PM »

Thank guys for all the reply.

Finally, took some photo on the carbs when I was adjusting the height.
Those who have done it, pls comment.

Side view before adjusting, it is tilted at 90 degree.

Front view

Side view, after adjustment 21mm. It is tilted at an angle of 80 degree.

After adjusting all 21mm, and I inverted it and let the float drop with gravity, 3 nos of float needle drop down and made the float stuck!
Am I doing the right thing??

super pasty white guy · « **Reply #12 on:** July 27, 2007, 05:07:10 AM »

I'm not familiar with these carbs, but are you sure you don't have the floats in upside down?

Dave

Trevor from Warragul · « **Reply #13 on:** July 27, 2007, 06:17:36 AM »

Definitely upside down!

Kevin400F · « **Reply #14 on:** July 27, 2007, 06:32:26 AM »

NO, the floats are not upside down!!! In the early pics, they are definitely out of adjustment. The latest pic looks like they're adjusted correctly. When the spring clip is reinstalled on the main jet and the bowl is installed, the floats will be restricted from dropping down as far, and should eliminate the "sticking" problem you noted when letting them drop freely with the bowls off. Looks like you're on the right track.

Morini---what makes you think the floats are upside down? I included a partial screen capture from an online parts fiche at http://www.mrhonda.com which shows the correct geometry....(rounded portion toward carb body, flat surface toward bowl).

crazypj · « **Reply #15 on:** July 28, 2007, 08:24:56 AM »

The last picture (with the rules) is showing 21.5mm. (or is it non-parralax from camera?)
Floats are right way up, not sure if carbs should be tilted a couple more degrees though?
PJ

Bodi · « **Reply #16 on:** July 28, 2007, 08:43:11 AM »

I don't want to take my running carbs apart to check, but in the picture it looks like they are at an angle that will press in the spring pins a bit when you're measuring the height, the float tang should just touch the pin but not press it in at all. The floats should be at the correct setting with the pin just touching at a height where the flat is almost parallel with the carb gasket surface: you measure the float height at the centre of the flat part, not the highest or lowest point. I have a carb set apart (where I work) and I will try to get pics next week.

yd72 · « **Reply #17 on:** August 01, 2007, 06:06:21 PM »

Sure like to see your photo, Bodi.

I sure like some more comments on this issue. I am still scratching my head anyway. Is this possible to achieve this 21mm in height? I personally feel it is not possible!
Anybody, has any step by step of the adjustment of the carbs? I think everybody will be delighted to see and use.

Bodi · « **Reply #18 on:** August 02, 2007, 10:31:58 AM »

Here are some pictures of a 400 carb body. The camera is level, the angle of the carb is as shown. First is the carb floats installed the right way up. Next is the float tang not touching the valve pin with the carb vertical. Then the pin spring compressed with the carb horizontal. Then the pin just touching with the carb at an angle. Last shows the 21mm setting with the carb angled to have the tang touching the pin but not compressing the spring.

yd72 · « **Reply #19 on:** August 02, 2007, 10:00:35 PM »

Thanks Bodi again.

Very good photographs and good information for everyone and my friends.
I will try it out. I think few of my steps are wrong.

News:

Author Topic: How to achieve float of 21mm for my cb350f carbs (Read 5703 times)