float levels

My carbs are dumping fuel from the overflows. I have cleaned all passages and installed new float needles and needle seats. I have set and reset the float heights to 40/64 (16mm +/- 1mm) measuring from the gasket surface to the top of the float with the carbs tilted over at apx 70 degrees to relieve pressure on the float needles. I have done on-bike wet float level testing with using a clear tube attached to the drain nozzles while bike is running and all of the fuel levels rise up just to the bowl screw. But, still overflowing.

I am now resorting to incrementally adjusting the floats outside of the 40/64 (16mm +/- 1mm) spec heights in order to see if they will shut off eventually and stop the overlfow. Is this acceptable?

When pressed down, should the floats be able to touch the carb bodies? Is my 40/64 (16mm +/- 1mm) float height measurement correct?

 

17.5 mm is correct. The tube method should show the level 3mm +-1mm down from the gasket surface. Sound like your levels are too high.


Also You should tap the carbs as they fill - dry needles/floats are know to stick.

 

Thanks, my factory service manual says 15mm to 17mm is within spec. I will raise them up a little more.

Aside from the overflow it is running awesome now.

 

I'd check the little float needle that the floats operate. Mine had come unscrewed just a hair. Which was apparently enough to keep the float from doing it's job. It was a bitch of a job trying to figure out the overflow. these carbs can be tricky but keep plugging at it and you'll be happy with the results.

 

found the culprit. the brand new aftermarket float valve pins i installed:

1) top springs occasionally sticking down when fully depressed.
2) not shutting off the fuel flow even with the float heights set to 17.8mm which is .8mm over max spec. Even though the float heights were correct when the floats fully depressed the pin springs the floats were bottoming out.

Although the new pins were seating correctly and sealing the valve on bench tests, they just didn't work when right-side up with fuel. I put the old original pins back in, re-adjusted the heights to about 16mm and low and behold NO LEAKS! The original pin springs do not stick and the floats do not come anywhere near bottoming out.

So, all I ended up using from my full 4 carb rebuild kit was the 4 new float valve seats and 1 bowl gasket.

Those needles cost me ten hours easy. I was sure something was sticking or the levels weren't right.

Spend the extra money for OEM.

 

cool glad you nailed it

 

Thanks again to everyone who responded to this post and all of my other posts. My bike is finally running great. I have riden my bike to work 30 miles each way yesterday and today. It is awesome. No more carb overflows.

Now I am working on a little fine tuning of the pilot screws.

 

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Thanks,
Rick

 

Pins???? You mean needles as in needle and seats?
Last week I tried installing new Sudco Hitachi needle and seats. I spent 5 hours and couldn't get them to stop overflowing. I gave up and put my old ones back in. Set levels and it runs good.
I found that the needles are 2 mm longer than the stock needles.
They cost me about $45. I'm not sure if I want to try them again. I was pissed and my garage reeked of hydrocarbons!