Motorcycle Repair: 1985 vf1100 Sabre vibration

Question
Hi, I bought this unseen and had it shipped, big mistake. It vibrated horribly when I first got it, on the stand as well as riding it. New plugs, cleaned and re-oiled the air filter, it got better. Had all 4 manifolds replaced, 2 were improperly installed, and carbs adjusted. Got a little better. Now there is no vibration when reviving the bike on the stand, but under acceleration there is. If you let off the gas at high speeds after acceleration, there is no vibration which I would think eliminates a bad tire. The bike has 24000 miles on it, it has the oiler mod for the cams and otherwise seems to run ok.  Drive shaft, worn out motor?

Answer
Hello Craig,

Most common issue on pre-1988 VF series (that could cause vibration) is punctured vacuum slide
membranes.
Remove the carburettors top cover and check each one for holes and/or rips.

Next comes camshaft timing. It's an easy-to-do mistake when reinstalling the camshafts of a pair of cylinders and time them wrongly compared with the other pair. Does your bike sound more like a V-twin? If yes, then look no further. Remove the valve covers and check timing.

Get back to me if you need guidance on cam timing.

Best Regards,
Lazaros.