Topic: Is there any way to repair a float valve?

[mycb750k6]

I have the early float valve for the 71 CB750s that leaks. I think they changed quite a bit in K3. Anyway there's the screw in seat with washer that screws into the carb and there's the floating thing with a little plunger on it that touches the float tang. What leaks anyway, the seat? Can that be lapped in. It's only brass. Or is it the plunger thing? what's that for anyway? I've noticed some plungers protruding further than others meaning swapping the needles would require a float height adjustment plus it probably wouldn't seat properly anyway. Anyway is there any float valve maintenance I can do to stop the leak other than just replace the whole thing? I don't know when I'll have any more money.
Thanks.

[jessezm]

I'd wait for others to chime in but on my K2, I dressed the float needles' conical surfaces with some super fine wet sanding and then some metal polish.  The springs behind the plungers were pretty shot, which makes it damn near impossible to set the float height correctly.  However, it did keep the floats from leaking until I replaced them.  Can you detect a worn-in ring around the cone-shaped tip?  that's what prevents them from seating correctly.  The lack of tension in the plunger will also mean that they are not held in place as tightly (remember, they are upside-down in the carb and the tang pushes against the plunger to keep them seated).

[ekpent]

Make sure that the spring on the tip of the float needle that touches your float tang is working correctly and is not gummed up with varnish or not functioning correctly. When the float height is set correctly it pushes the needle up to shut off fuel flow. Also some of the JUNK after market carb rebuild kits just work like CRAP. Do you have stock stuff or CRAP aftermarket.Look for a Kehin logo on the slow jets,rubber or stock gaskets etc for a clue.I am going to do a thread and show how BAD some of that stuff is.

[mycb750k6]

Jessem,
I can clearly see the ring on the cone of the needle. In fact that seems to be quite common. But I have a bunch of old needles around I could try chucking up in the dremel with semichrome or something to see if I could smooth it out in the seat. The key is the needle and seat much match I would guess, like a valve seat?

And ekpent, I wouldn't have any idea if they were after market CRAP or not. Could be as the PO said the carbs had been 'rebuilt', a word that sends shutters down my spine. I'll pull it out and take a picture. Can you tell from a picture? The seat has a little 2.0 on it but I have others in the 'box' with 2.4 or 2.5 on them. Maybe F carbs.

When I thought I'd fixed this last week, I pulled a float valve assembly plus it's float from a working K1 set so I wouldn't have to redo the float height. That was a good assumption wasn't it because the plunger length and tang would match? Anyway pushing up on the float now does not stop the drip.


And while I'm at it, what effect on mid-range acceleration will a single too full float bowl have?

[ekpent]

Sorry about being negative on the aftermarket stuff but I bought a K1 last week I am going through and the aftermarket #40 slow jets compared to stock Kehin ones are so big you could drive a truck through them  The float needles did not want to drop down in the holders,just not as good as stock stuff.  Not sure why a known working set from another bank though would not work on your carb body 

[mycb750k6]

I didn't take it  negative. I appreciate the response. I'll try lapping and see where that leads. My idle jets all seem to look the same with the 40 on the side. I don't recall seeing Klein on them though.

[ekpent]

Look to see if there is a stylized "K" logo stamped next to the 40. Also if you have a know stock 40 slow jet that is clean,look through the hole and compare to whats in yours just for kicks.