Getting sick of my carb situation KZ750 H3

Carb 3 leaks out of the overflow. I polish the seat and it stops leaking. A few months later, Carb 2 leaks for the same reason. I polish the seat and it stops. A month later, Carb 3 is leaking out of the overflow again...

I have a fuel filter and it is no where near time to replace it... what is going on?

Is there some modern carb assembly I could get that's still being manufactured? I saw some Mikunis that are supposed to fit other models of 1982 KZ750, but it didn't list the H model...

I have the stock Keihin CV34 carbs that came with the bike, and they were remanufactured by Wired George, and he did such an amazing job that I'm just dumbfounded. Every time I polish the seats, there never appears to be anything to be making it dirty when I look visually...

I'm starting to get really annoyed...

If you bend the tang too much the needle will cock sideways and it will leak.
Steve

What Mikunis did you find & are they suitable for ganging them together into a 4 carb bank? A link would be good.

From the 750-4 manual. models w Mikuni BS34 carburetors. 82 R1, 83 L3, 84 KZ700 & 84/85 ZX750A models.
edited to include the R1 & L3. see following reply by Nessism

Mikuni BS32 carbs. 82-83 KZ650-CSR. same airbox as the 750E/H models. same carb holders & airbox ducts.

For more recent carburetors you can probably use the carbs from a 99-2005 ZR750 (ZR7 & ZR7S), but I think they all had Keihins.

Kawasaki started using the Mikuni BS34's with the 1982 GPz/R1 750, and continued that with the L and ZX series bikes. I'm not sure about the boots needed but installing them should be doable. That said, just fixing the carbs you have is the simplest path forward. It sounds like debris is getting through from the tank to the float needles. Using a fuel filter won't save the day if your tank is rusty because gravity feed type fuel filters are not able to filter fine particles.

I haven't bent any tangs.

The Modern Mikinus I found were Mikuni RS34-D21-K RS

I had my tank de-rusted and gelled professionally so there shouldn't be any rust getting through.

I'm using a cone shaped filter and the petcock is vacuum actuated rather than gravity.

I've rebuilt/restored several sets of those Keihins and have found them very finicky regarding float valve sealing. The float needles are rubber tipped and the needle springs are designed for light seat pressure. After 36 years the rubber can deteriorate and many times the needles should be replaced. Real deal Keihin needles are still available but expensive. Aftermarket needles range in quality from decent to crap. Any which way you choose it's important to perform the clear tube test to verify fuel level in the float bowls before putting the carbs in service. Very few carb restorers do this extra work though. I don't know about Wired George's rebuilds but from what I've read, the restoration quality from his shop varies quite a bit depending on who did the work.

Partzilla should have the float valve as there is a photo of it. $27.35 + sh.

From a quick internet search of the RS carburetors. google search = Mikuni RS34-D21-K RS fitment.
other searches may yield more info. such as RS34 fitment or whatever.

mikunioz.com --- Mikuni RS34 ... Excerpts from the description:
Before rushing in and ordering please firstly check your carb spacing and carbie sizes for compatibility (the spacing is listed).
This Mikuni kit comes with the following carb centre to centre spacings for direct fitment to ... ALL, Kawasaki KZ 750. et al.
The OD at the motor end on 34’s is 40mm. OD at the air-cleaner end is 55mm. Front to back length is 100mm

ps: a vacuum petcock is still gravity fed. the vacuum feature basically makes it an automatic fuel valve. engine vacuum actuates a diaphragm to allow fuel to flow by gravity. when the engine stops, a spring returns the diaphragm to the closed position. the diaphragm assy has a plunger w o-ring that plugs a fuel port on the petcock body when the engine is off.

I had to bite the bullet and order all 4 float valves for my 29s.... 2 were leaking and one just barely ...... since they have no over flows its doubly important that they seal up.

jetsrus.com/individual_parts/018_880_su.html

$9.82 each for real deal Keihin needles.

These are cheaper... www.amazon.com/gp/product/B00NO5OMQG/ref...06_s00?ie=UTF8&psc=1
I've used them before and they are passable, but I recommend spending the extra $20 for the Keihin parts.

Setton wrote: I haven't bent any tangs.

The Modern Mikinus I found were Mikuni RS34-D21-K RS

I had my tank de-rusted and gelled professionally so there shouldn't be any rust getting through.

I'm using a cone shaped filter and the petcock is vacuum actuated rather than gravity.

The RS34's I have develop an occasional drip only when parked at an angle on the side-stand.
IMO the fuel migrates between carbs as it seeks to level, and it eventually breaches the top of the drain tube in the lowest bowl.
It may not leak if the bike sits undisturbed, but if it gets jiggled or moved the slightest amount, then some fuel will inevitably drip. :huh:

I shut my petcock off just before entering my drive and lower the level a little and then use around a 2 inch block of wood to keep the bike a little more level (but not to much or it gets pretty tippey) to keep the new bowl gaskets dry.

martin_csr wrote: Before rushing in and ordering please firstly check your carb spacing and carbie sizes for compatibility (the spacing is listed).
This Mikuni kit comes with the following carb centre to centre spacings for direct fitment to ... ALL, Kawasaki KZ 750. et al.
The OD at the motor end on 34’s is 40mm. OD at the air-cleaner end is 55mm. Front to back length is 100mm

So it will fit the H3 then I take it?

I think I'll try Nessism's suggestion to use real keihin needles, first. Then if that doesn't work I'll bite the bullet and buy a set of RS34s... I'd prefer just to get what I have working right, but if that doesn't work, I'd rather have something modern, for which parts are still available.