Last nite's trip with my kids seems to confirm that the TiiCo vibration demons are gone.  Did two things yesterday. Filled the frame rails where the engine cradles attach with polyurethane foam. Right and Left sides from forward of the firewall all the way back, and accross the rear.  There are lots of openings to squirt into.   Called Great Stuff (Minimal Expansion), it's used mostly for insulation in houses. The idea was to deaden any vibe transmission or "ringing" through these channels.  Seems to have made a big difference.   If you try, WEAR GLOVES!  This stuff is VERY MESSY and does not come off skin.  It has to wear off. 

I then dropped the shift linkage and "rebuilt" it without using new parts.  I figured that most with the TiiCo engine are reporting shifter buzzing (including me), and that since the shifter is one of the only direct connections between engine and body (no/little rubbrer between) it would make sense that it's transmitting vibes. I knew that the rear shift rod bushings (nearest the selector arm) were worn, so maybe tightening them would interrupt the sympathetic vibes of the whole rod.  Removed the shifter rod from behind the gas tank to the selector, put it on the bench and opened the clamshell steel mount that holds the plastic bushing.  Very worn and very dirty.  Old grease, grit and sand.  Surprised the shifter moved at all. Looked like the only way to remove the bushing was to drive out a drift pin on the selector arm and remove it?  Nah.  That's asking for trouble. Decided to cut the plastic bushing on the diagonal with a small coping saw.  Got it off, cleaned and removed more material from the slot where it had been cut so that it could grip the shaft more tightly.  To get it to grip more tightly, I cut some rubber from and old bicycle inner tube to place between the clamshell mount and the bushing.  When installed, it now closed the gap that I had created where I cut it open.  Reinstalled and found a nice change.  Besides the shifter being much more accurate and direct...no more buzz. 

 

After my crusade to kill the vibes, at around 4k rpm I can tell that the engine is in it's vibration period, but nothing in the body resonates with it. Now winding this engine up is really a pleasure. 

 

Gary