Hi Gordon
A few thoughts:
**Although you stated that you have balanced the carbs, did you check that they
are being opened the same throughout the throttle range? Do you have a kinked
or otherwise compromised set of cables? Did you try balancing at around the
throttle
position you are having a problem?
**Are your carb float bowl vents in good condition and both plumbed to approx.
ambient pressure?
**If you switch from both to left then right mag, is there a change?
**I am not sure, did you check the tracking of the blades? Did you measure that
the blades are the same pitch, especially at the approx pitch where you are
having
vibrations?
**Did you ever dynamic balance the blades?
**Did you do the mod to undercarriage mounting frame? Is it or the motor mount
cracked? Is the engine mounting bolts (Binx nuts) properly torqued? Are the
motor
mounts in OK condition?
**Is the choke (enriching circuit) cables completely closing the arms?
**Is there a leak in the balancing tube?
**When was the last time you replaced the spark plugs? Is there a chance you may
have wires that got mixed up?
**Is the spinner tight with screws tight and no cracks and does it track true?
Is the backing plate cracked? Did you by chance install different hardware where
on the spinner, back plate or other is causing the prop to be out of balance?
** How many hours on your gearbox since it was checked? Do you have a slipper
clutch?
Do you use 100LL a lot? do you have a problem starting?
Have a look through here, especially vibration:
http://www.europaowners.org/forums/gallery2.php?g2_itemId=81550
Ron Parigoris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=348176#348176
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