Message text written by Cliff Hansen
>After balancing with a Unisyn and setting the mixture the old
way (lifting the piston and listening), I have noticed that the
front piston lifts noticeably more than the rear when maintaining
3000 rpm. The front is up about 1/2", the rear is about 1/8" lower.
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Cliff, The higher rise of one piston would suggest either more
vacuum to one of the carbs, or that the piston spring on one side
is weaker/stronger. Try switching the springs and then see if
the opposite carb now rises higher.
If so, one of the springs is out of spec, but it will be tough to tell
which one.
The spring is carefully chosen so that the piston just reaches the highest
level
as the engine reaches peak RPM (has the most air demand). You could try to
advance the throttle and check the height at 5000 rpm. If the high piston
has already hit max, then probably its spring is weak.
Another possibility (not vacuum or spring) is that there is something
binding
around the piston and restricting its motion.
Slowly advancing the throttle to max RPM while watching the piston
SHOULD be infomative. Do both pistons move smoothly? Is one
too high or too low at/before max RPM?
New springs are $3.00 each from Moss. New piston & Chamber
is $75.
-Tony
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