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Carb help needed

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70herald

Luke Skywalker
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The herald has a carb problem. (CD150 - no emissions stuff)

I can't get lean out the mixture at all. Using my nice new Colortune. I always have VERY rich mixture - dark yellow. In fact, it flood the 1 and 4 cylinders starting cold.

When I tighten up the jet it eventually starts stuttering, still looks rich and then stalls. At that point the piston is jambed WAY up, about 1mm above the normal bottom.
 
Hmmm. Is the piston traveling freely? That is does it return to the base with a nice solid clunk?

Sure the needle is the correct one?
 
W/o the damper, piston moves smoothly, with the damper, obviously it is more difficult to raise but comes down nicely. With the jet somewhat lower, it goes up and down.
Needle is new from Canley and is supposed to be correct.

Thinking about this a bit more I am starting to wonder if something is stuck in the needle valve, or maybe the float is not floating?????
 
Assuming you still have the old mechanical fuel pump. First suspect would be the fuel level in the float chamber; particularly if it smells strongly of raw gas and there seems to be a fuel wetness hanging around in the carb throat with the engine off.
This can be from a needle valve that doesn't shut off properly, a float that has gas inside it (leaking), or as was the case on my TR6 a float that was maladjusted putting the fuel level too high.
 
I've always loved the expression "raw gas" for some reason... Yep - gas level could be too high for the reasons mentioned.
 
tdskip said:
Did you change anything beyond the needle?
Click to expand...
Just about everything :yesnod: I got the "rebuild kit" the one that comes with throttle shaft, butterfly, everything that moves, but last year, it was working, after I did the rebuild so something seems to have changed over the winter.
 
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