Wednesday, May 22, 2013

Mon. 13 May, I took the Dondolino up to the USCRA event at NHMS, Loudon, N.H.  It ran well the first practice but, starting the 2nd lap of the second practice, it suddenly started running poorly and I pull right off.  I found the high tension lead on the magneto loose.  That's got to be it.  I tightened it up and started it up again.  It would idle alright, but if I gave it throttle under load,  it would stumble badly.
Looking the motor over again, I notice the exhaust valve lash cap was missing and there was huge clearance there.  I started to replace the lash cap, but noticed the action of the rocker wasn't smooth.  I took the rocker box apart and saw the exh. pushrod wasn't sticking out as far as the intake.  I then took the timing cover off and found the problem.  The motor has roller rocker cam followers and the exh. roller spindle had broken and the roller was laying in the bottom of the case.  This allowed the rocker to bear directly on the cam lobe and galled it up.
Open hear surgary

the left (exh.) cam lobe worn by the rocker.  Mark Gibson photo

intake on the left and broken exhaust on the right.  Note the worn and discolored rocker were it rubbed the cam lobe directly.
It's not clear yet why it broke, but the Dondo was done for the day.

Henry Syphers let me race his 550 Honda four in the Heavyweight Super Vintage as he was just racing it in Super Masters.  My practice on it consisted of one 'scrub' lap and the ergonomics were all wrong as Henry and I are quite different sized.   But, I had a fun ride and finished a distant 3rd behind  Rabbie Demetrius and Rich Midgely and ahead of Kerry Smith on their 350 Honda twins.

To me, the highlight of the event was Jim Jower's recently acquired Rudge.  It's a 1930 chassis with a 1934 motor.  The motor is a 500cc four valve single.  The intake valves a parallel, but the exhaust are radial.  The exhaust pushrod opens the right exh. valve via a rocker.  This rocker also operates a second rocker which actuates a third rocker to open the left exh. valve.
Rudge valve gear

The bike has two front brake drums and twin carb floats.  I ran well in practice but when off song in the race with suspected magneto problems.
Another interesting bike was Frank Camillieri's Yetman framed 100 Yamaha.  Frank told me this was the first Yetman frame they made.
The Camillieri's also had an AT-1 Yamaha with a home made cylinder head.

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