GPZList Digest, Vol 40, Issue 29

[schnowz]

If it was running OK before the only way I know for it to get richer is with the float tang wearing or bending, float needle leaking or an air passage got clogged. If you have to adjust the pilot screw  you may be going after the symptom  - not the cause.
You don't have to take the carbs off just to check the float height.
Course if you get it to run right at least you know it's carburation related.

    Pete S
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I'm
thinking (initial diagnostics) are to reset the idle screws a bit

 leaner (2
turns?). I've avoided messing wiht the carbs because 
they're
 such a
difficulty getting in and out, but I may just have to 
'suck
 it up princess'
(as a couple buddies have been know to say), 
and
 just do it, damn the
difficulty.

I'd check the float height 
with a clear tube on the carb drain before making any adjustments.
?Also
 as others have pointed out the battery can do that if the plates short 
out with buckling from heat - but if IRC it doesn't crank either.
? 
If all else fails clean the carbs..

??? Pete S