Hey Guys,

I'm trying to get my Keihin CVK (thats what I think they are) carbs running properly but there are a few issues I need to get sorted first, before I can actually fire up.






First question is regarding the drain plug screw at the bottom of the fuel bowl; on my carbs each screw has a flat end on the tip - not properly sealing the bowl. At first I though one was worn but they are all the same.

Is it normal for the bowls to NOT be completely sealed at the drain screw?

I'm wondering that if I do drip feed the carbs there probably wouldn't be enough pressure to push the fuel out of the bowls via the drain? Any comments?

I cranked the engine a while ago and discovered alot of fuel leaks, turns out the built in fuel rail seals were expired. There was also a bit of fuel coming from the drain plug holes but it was difficult for me to confirm as it's all a very tight fit. I'm just wondering whether the leaks (from the bowls) will still happen when the pressure is dropped from the stock facet pump pressure to drip feed.

to much fuel pressure
float level to high( fuel pressure )
drain screws have flat ends but are tapperd
fuel leaking out of overflow, flooding
drain/overflow uses the same fitting
bowl overflowing, not leaking out of drain screw
should be able to set flot level lower to compensate
for higher fuel pressure
tommo

you may be missing an o-ring on the drain screw, some carbs have them, (mikuni's on smaller kawasaki bikes I have owned)

p.s. your intake runners look quite long, should be more torquey, was that your intention?

Chris you need the fuel drain hoses to be directed away from the exhaust area.
I put mine in the past through the brake line hole and attached on the inner
firewall area of the guard.
They only drained once when first running them due to perhaps dirt in the
custom made gravity fed fuel bowl.
You best run a fuel regulator at 3psi as I remember someone elses practice.

There is some info on the carb online for the enthusiast restorers of that
particular Honda model. It has exploded diagrams etc.
Do you have the model number exactly?

It is a good choice to go these carbs but must be tuned on a dyno or you
could end up with glazed bores which I did on my first version of the mild
cammed 77.5mm bore a15. A blast once tuned and ignition curves sorted.

i just love your balck and white photos chris, that chrome looks fantastic. can you email me some in hi res, i need new desk top pics ;)

sounds like somethings missing, fuel shouldnt come out the bowls unless seal missing or too much pressure as tomo said(and D).

2 to 3 psi thru a reg should be fine.
are carbys on same angle as on bike??

The fuel in the bowl isn't pressurised so the fuel pressure isn't your problem, unless it's blowing the needle off the seat and causing the carbies to flood. I ran 6 psi fuel pressure with a facet pump and never had a problem with flooding.

Yeah okay sounds like fuel pressure is the issue then. Model is a Keihin CV34.... and I think the CVK may mean that they're of a Kawasaki - (Constant Vacuum Kawasaki?). They're very similar to the Mikuni BS34.

I'm pretty sure the carbs are on the same angle as they were on the motorcycle. I have seen a few pictures of them fitted and they're definitely level.

I'll replace the seals along the fuel rail built into the rack and run them again at a very low pressure and see what happens.

So it's normal for the fuel bowls to be open? I guess that when they overflow they simply drip?

These have a really good reputation for fuel economy so I'm also looking forward to that, but I really want this car up and running.

Remember motorcycle carbs are gravity feed; I my Keihin Flatslides I'm running a regulator at 2 P.S.I. , much higher and the float needles won't seat. At 3 P.S.I. gas flows out the float bowl vents.
Most bike carbs have a vent tube in the float that sticks up above the float level, rather than pour down the throat it leaks out the vent line. The vent line normally extends just below the swing arm pivot (at least on the four bikes my garage are) One other consideration on CV carbs is the spring acts as the damper rather than the oil in a GX carb, so if you need to change the rate the slides and importantly the needles rise you need to change spring rates....just a tuning note.

Tom

Thank Tom!

Lots of useful information there. I've repaired all the leaks and put a little in line tap in the fuel line to limit the flow. I also have a softer spring that I intend to put in the fuel pump to alleviate the back pressure on the facet diaphragm.

I cranked the engine with no spark plugs in and I let the fuel pour into a container, looks like the flow is nice and gentle, must be careful not to mess with the tap. I also found that the fuel is a little old, so there is another thing to look at before I can even expect to get this one the road.

So in changing the springs/spring rate of the slide what would one expect to achieve? sharper throttle on acceleration? How would the light pressure spring affect the return of the throttle..... Or is this more an issue with how one would drive the engine? Obviously if the throttle is blipped/revved/wrung at frequent intervals (like motorcross etc) one would prepare a heavier/stronger spring rate to ensure the slide is back at it's original position ready for the next acceleration?

Is that the general gist of things or have I lost it?