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It's a vacuum-operated petcock, so when the engine stops, the fuel stops. Somewhere between the vacuum port on the carb or throttle body and the valve in the petcock, it's gone wrong. Plugged vacuum line, fuel valve, stuck diaphragm, and perhaps something else has stopped it working.
 

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Discussion Starter #3
I changed the tank. and the petcocks are from a special unit.

The vacuum diaphragm is brand new, It was doing this before I changed it,

I can check it again, but I just changed it last week.

could it be a plugged gas cap pressure release on the tank?
I heard it hissing along time after I shut the engine off.
 

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could it be a plugged gas cap pressure release on the tank?
I heard it hissing along time after I shut the engine off.
Yeap, could be. Try opening the gas cap next time the bike stutters and see if that helps.

You can also check the line to the petcock with a vacuum gauge while turning the engine over. You'll have to find the vacuum specs for your particular bike though.
 

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Discussion Starter #5 (Edited)
found the cap was plugged up good, opened the orifice with a drill.
Still stutters, but it seemed to help a bit.

Good idea with the open the cap thing! heh heh!

How about cracked carb boots? could that do it?

I might need to clean the carbs out with a tool...

wanted to post this pic of the paint job... it is gunmetal black and orange metal flake, over Canyon Brown Poly(obsolete). the rest of the bike is oxide red and yellow mix....I used the same flash on it, and is just looks bad!!!!
I think it looks wild
 

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Discussion Starter #6
float level was off, so i pulled the carbs again today...
the manual says the bottom of the floats is supposed to be 1.01" from the throttle body without the bowl gasket... yep the floats were out exactly the way the fuel level was in the test before I pulled the carbs! bend the tang, fix the rich/lean prob.
 
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