Drippy Carb

[robert campbell]

Hello,
Time to ask the experts again. My 1972 Hodaka B+ suffers from film around the float bowl. I have had it running for a couple years now and it is just right on for tune and fun. It is a stock VM20. For the last two years I had it running with a new float and needle/jet assembly. It seemed odd at the time when I put the this float/needle/jet assembly together that the tang on the float would not reach down far enough to touch it. I had to perform some near reconstruction of the tang to reach it but all and all it seemed to work fine except for the film. At one point I thought that I had a countershaft seal leak, but it was the carb. It is not a huge leak, but annoying. I am confident it is not coming out of the overflow port or the gas lines. I have the new style fuel petcocks.

I tried to get one from Paul. but he does not have any floats or seats right now. I got a perfect used one, except the needle has a tiny groove on it, but it seems to hold. I found out that the first needle and seat combination was quite a bit "shorter" than the used one I have now. This combination fits right in and has a nice 7/8 inch height on both sides, no gasket, with nearly no adjusting of the tang what so ever.

So, I assembled it and back on the bike we went. As soon as I turned the gas on it was weeping around float bowl. I am confident that the float level is good, but the needle and seat may not be holding? Before assembly, with the carb upside down with the float "weight" on the needle, it seemed to hold when I blew into a gas line I put on the carb to test it.

I must be missing something. It runs fine, but I can tell that the float may be a little higher than before as the idle changed just a bit and it starts a bit harder when hot.

1. Is there a better float level setting?
2. Does anyone have a new or good needle and seat?
3. Gasket is new (twice) and it would seem that the float bowl should not leak even with a high level?
4. What am I missing?

Hope to cure this soonest, so I can go to Hodaka Days. It can go like this, but heck, I hate weeping gas. I was on-line and found a Canadian company that is selling parts on Ebay. It looks like the Kawasaki KD and KH 1976 series bikes used a VM20. The float looks similar. Does anyone no if this will interchange?

Rob

[matt glascock]

Robert, have you precisely located the site of the leak? It sounds like from what you are describing it is leaking where the float bowl mates to the carb. Several issues may be occurring. The mating surfaces may be deformed from improper tightening courtesy of a DPO. Try laying the gasket surface of the bowl on a precision flat stone, plate of glass, or other flat surface. If it rocks, it will need to be lapped. Obviously after performing any lapping operation, make sure to THOROUGHLY wash the parts lest you'll introduce metal particles into the engine - bad. Also look for cracks around the screw holes as a result of the same improper tightening. Make sure there isn't any crud, varnish, cheese whiz, etc. in the gasket groove on the carb. Sorry if I'm missing the point on the site of the leak.

[Bullfrog]

Matt's advice is quite good . . . but I'd like to add that I've seen carbs which have never had improper tightening of the screws . . . but which exhibited leaks at the bowl to carb body gasket. The leaks came from the "ears" of the float bowl being bent slightly. This results, over time, due to the pressures being highest right at the screw heads, and the "ears" press further into the gasket than the rest of the sealing surface . . . and they take a permanent bend.

The "ears" can be gently coaxed back into plane then a light lapping can really true up the sealing surface. As I recall, you might have to do the lapping on a surface with hole in it to accommodate the vent riser tube. I've used 3/4" MDF (medium density fiberboard) as the lapping surface to make custom "lapping plates" with holes. It is certainly flat enough for parts the size of the float bowl.

You might also want to use a magnifying glass and inspect closely for die casting flaws or cracks. Odds are against finding something like that, but then again . . .

Ed

[matt glascock]

Good call, Captain. I was not aware of that potential development with the float bowl "ears". Good to know.

[robert campbell]

I am fairly sure that the leakage is the float bowl to the carb gasket area. I will remove the carb and disassemble and check the bowl flatness. This happens on Holley accelerator pump housings all the time and I have flattened and smoothed them to achieve a flat surface. a sanding block is a huge help.

Does anyone know of the parts for the Kawasaki carbs? Below are links the them. They look very similar.

Rob

http://www.ebay.com/itm/NEW-KAWASAKI-OE ... lA&vxp=mtr

[robert campbell]

Here is the link to the float.

http://www.ebay.com/itm/Kawasaki-KD80-G ... cg&vxp=mtr

[Bullfrog]

According to logic (seemingly not always applicable) - if your float or needle/seat were the cause of your problems, you would see excess fuel exiting the vent tubes. So . . . long distance diagnosis based on the description of symptoms is as offered in my previous post.

Um, keeping mind that a weeping tank petcock or fuel tubing joint will result in a damp/wet carb body and float bowl. (and a lot of problems of that sort have been solved after the owner has clearly stated that his fuel valves do not leak . . . by re-checking for leaky fuel valves )

[Bill2001]

Yes. Remember that although you may think that the leak is coming from a certain place, it may be coming from a fuel line or a fitting or somewhere else.

[robert campbell]

Bullfrog,
I agree. Any thoughts on the Kawasaki float and needle seat assembly? I would like to have some fall back parts. I will address the float bowl ears and flatness.

Rob