FIRE in the intake pipe!!! (carb work)

82 apencade:
Brought my bike back to life recently (currently)... compression
is great (which suprised me for 75K miles). Cam's are within service
limits, timing belts are tight, cyclinder leak down says about %5
percent on each cylinder (again, very suprising for 75k). valve
tappets are set. I pulled the carbs, removed the gum from pri and sec
jets, needle, etc, checked vacum pistons, set floats (3 of the 4
floats were very lean), carbs are synced (all at ~7-8 in/lbs at idle,
~13in/lbs at ~1400 rpm).
When I went to re-check the carb sync's late one night, I noticed
that on #4 card, when I removed the little screw, that 1/2" flame shot
out of the screw hole almost every time that cyclinder fired. It
didn't do this on the other cards. Any ideas? I don't 'think' it
does this when the screw is back in it.
Before I sat the bike up (not on purpose), the bike didn't like
going paste~70 mph. I was hoping that after the carb work, that it
would act better, but no... still the same feeling of slow
acceloration, and low top end speed. And for an 1100, it sure doesnt
have the acceleration that my older 79 gl1000 did. Fuel press/flow is
all good. Strange how everything seems fine, but it just doesnt have
the 'go' that it should have. Any ideas???

 

Check that you don't have a broken intake valve spring, had it happen to me
twice in 20,000 kms
I bought the bike after it sat for a number of yrs and I suspect
condensation caused rust pitting on the valve spring and after a while of
working and flexing the spring if finally broke at the pitted area.
The first time it caused a bent valve, but the second time I noticed a lack
of performance and popping back thru the intake at higher rpm, but it would
idle fine. So I pulled off the head cover and caught it before any further
damage was done.
Total milage is only 61,000 kms or about 35,000 miles
82 Aspencade.
There are two springs per valve and you may have only one of them broke.
The reason the leakdown test wouldn't show this is the air pressure holds
the valve shut.