Topic: Float height adjusting

[UK350F]

Ok, Iv'e rebiult the carbs on my 350F. Just a little confused how to adjust the float height.

I know it says set to 21mm from when the float just touches the needle, but the float tab touches the needle all the time or it will fall out ! what am I missing here guys?

 

[bollingball]

Take your float off and look close at the float needle it has a wire on it that the float tang slips through now push on that wire and you will see it has a spring inside. When you tilt the carbs to set the float you don't want the weight of the float to compress that little spring.

Ken

[flybox1]

Not on the 350F bollingball 
UK350F, they wont fall out.  your floats shouldnt pivot out past that point.
roll the carbs onto their long side, where the floats hang down from their pivots, resting on the needle tips.  set your floats at 24mm  

the 21mm float height is wrong for stock 350F carbs

[Deltarider]

1. Why do you think you have to adjust?
2. More than once I've seen people put in 350F floats in upside down.
3. Float height of 21mm is correct for 350F and 400F.
4. Float height is always correct except when PO has messed with them. Very rare, unless PO was reader of this forum.
 

[mono]

i don't think my PO is/was on this forum, and when i took apart my carbs to rebuild them, all of the float heights were different.  vastly different, and none was at the correct height.

if you've got the carbs apart, you might as well check everything! 

[flybox1]

i don't think my PO is/was on this forum, and when i took apart my carbs to rebuild them, all of the float heights were different.  vastly different, and none was at the correct height.

if you've got the carbs apart, you might as well check everything! 

+1

Per Hondaman, the fuel level, for all of our CB's should be at 4mm below the bowl gasket seam (using clear tube method)
To reach this optimal fuel height, floats for stock carbs and floats on 350F's needs to be at 24mm's.
21MM in Clymer is a misprint.

[bollingball]

Not on the 350F bollingball 
UK350F, they wont fall out.  your floats shouldnt pivot out past that point.
roll the carbs onto their long side, where the floats hang down from their pivots, resting on the needle tips.  set your floats at 24mm  

the 21mm float height is wrong for stock 350F carbs

Fly what are you saying they don't have a spring in them. I have never worked on a 350. Sorry for any bad feed back

Ken

[flybox1]

Hey Ken, no worries.
They have then internal spring just like all the others, but they dont have the little wire loop on it that the float tang fits through.  the needles wont fall out as the brass pivot between the floats hits the float posts before they open too far.

[phil71]

if all 4 were that far out, I'd be suspect of where you're measuring from.

[UK350F]

Thanks for the comments.

I need to check them before I finish the rebiuld. 2 are 21mm and 2 are 23mm. I have 3 manuals that all say 21mm.

I checkd the needle valve in the closed position just touching (but not compressing) the spring. I'd guess that 21mm is correct for a 350F since all the manuals give this measure.

I inittially checked the level while the carb was in the upright position, hence the valve always touching the float tab.

I realise this was not the correct way to check them.

baffles me how they could ever got to be incorrect, it's not like anything every puts any pressure on them.

Ive set them all at 21mm now but if there is a problem with running i'll have to set at 24mm as previous post mentions.

[lucky]

Take your float off and look close at the float needle it has a wire on it that the float tang slips through now push on that wire and you will see it has a spring inside. When you tilt the carbs to set the float you don't want the weight of the float to compress that little spring.

Ken

With the new plastic floats you do not have to worry that when the carb is upside down and you are measuring the float height that the float will depress the needle valve.
IT is not heavy enough with that light weight plastic.

With the heavier brass floats it was a concern.

[Lostboy Steve]

1. Why do you think you have to adjust?
2. More than once I've seen people put in 350F floats in upside down.
3. Float height of 21mm is correct for 350F and 400F.
4. Float height is always correct except when PO has messed with them. Very rare, unless PO was reader of this forum.
 

lol +1

[bytio]

What effect on the performance does an incorrect float height have?

[flybox1]

too much or too little gas in the bowls..

[lucky]

Take your float off and look close at the float needle it has a wire on it that the float tang slips through now push on that wire and you will see it has a spring inside. When you tilt the carbs to set the float you don't want the weight of the float to compress that little spring.

Ken

Some float needles do not have the wire.
If his needle is falling out then there is the problem.

[ewanhughes]

When I took the big bold step of stripping down my carbs for the first time I found the document below to be invaluable.  It is fairly idiot proof and takes small simple steps with loads of good pictures.  Pages 14 to 16 show a great way of getting your float height right.

I can't post an external link but the doc is by a guy called Tim Boughen and is called carb rebuild 101 or carbv02.doc   and it''s easily accessible on t'internet.

[HondanutRider]

This may be what you were referencing: www.cb400f.btinternet.co.uk/carbv02.doc

[jstfkndi]

Just rebuilt the carbs on my 350F and got no overflow when setting the floats to the 24MM mark. Yes they are in correct and they are black (not sure if plastic or hard rubber). Guess you can go with the manual settings and if it doesn't work, pull em off and set them farther.

[jessezm]

You won't get overflow setting the floats at 24mm because by doing that you are actually LOWERING the fuel level in the float bowls when they are right-side-up.  It's an inverse relationship.  While I've always seen 21-22mm as correct for the 350 adn 400f, I myself set mine at 24mm anyways to try to compensate for some off-idle richness/bogging.  It seems to have helped.  But if you are running completely stock there's no reason to deviate from the recommended levels, I would think.