DOHC float heights

S

Snoosky

New Member
While interrogating my carbs, im noticing all of my floats are consistently out of spec. These are the plastic non adjustable type. Im measuring these with the floats hanging down. Honda says theyre 0.61" from carb base, mine are 0.8-0.9". Im thinking a possibility of incorrect float valves or is it reasonable that these are just old and their warped equally over time? The valves measure about 0.68" in total length. I'd hate to spend $100 on new floats to find out the same measurements. Please tell me im missing something here.
81 cb750C
Keihin VB42A
 

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Bought the bike non running. Thought i might get lucky and not have to tinker with the carbs. Noticed fuel leaking from the 1/2 carb joint when i was ready to start her up.
 
Snoosky said:
Bought the bike non running. Thought i might get lucky and not have to tinker with the carbs. Noticed fuel leaking from the 1/2 carb joint when i was ready to start her up.
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Dont mess with that just yet, clean them, inspect the needles for damage and get new gaskets and try to start it up then. I usually clean the float seat and passage as far as i can with q tips
 
Ive done the cleaning which didnt affect float height. Ive read theres a tolerance +\- 1 mil for floats but mine a a good quarter inch from that. I dont recall the bowls leaking out the overflow, just thefyel joints. And to complicate matters i found the secondary main jet a 120 instead of stock 102. I still need separate the carbs to fix the fuel joint leaks. It seems like ive opened a can of worms with these carbs. :o.
 
Are the float valves worn?


needle.gif



This would explain why the float height is out of spec if nothing else has changed.
 
Float valves look good, no indentations or wear. When i pulled the hinge and look at the floats they dont appear to mis shaped in anyway. Im really starting to think ive got an incorrect (longer) float valve to make this thing stick up so much higher. Any shop guys or carb gurus with a few of these around take a measurement??? Mine are about .68" long.
 
Sorry - I was thinking your float height was too low, not too high.


Do the float needles have spring loaded tops? I think you might be measuring them wrong if they have - carbs should be at about 45 deg in most cases.


Or if not, maybe you can trim down the float valve top pins?
 
The first digit of the scale is on the base of the caliper (hard to see in the pics) The general measrument of these valves is 0.658" and yes they do have a spring loaded pin on top
 
You don't measure float height like that. Carbs should be set at about 70 degree angle so tab just touches pin of shut off valve.
They are adjustable but you have to be real careful not to break stainless tab off the plastic
 
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