quiz answer

[Michael Mulholland]

thanks to all who replied with answers. you were all in the right area and
most of you picked the woodruff key on the harmonic damper as the most
likely. it was not the woodruff key. as it turned out i redid the timing
belt three times not believing that i could have overlooked something. i
have done these several times already. after the third time i took each
component off and examined it carefully..cam pulley...ok, timing belt
...ok, damper ok, cog for timing belt on damper..ok, no, hold -on
here...seems to be a lot of dirt between the teeth, but only on half of the
teeth , hmmm, just happens to be on the teeth that are invisible when the
timing is set. the dirt filled almost the entire gap between the teeth. it
was evenly spaced and did not quite allow the belt to slip. in fact the
dirt raised the belt and made it tighter. the result of the raised area
over half of the cogs was that the gear ratio of the crank to the camshaft
was changed. the crank pulley was now egg shaped and thus a larger diameter
so for each revolution of the crank the camshaft would turn too far. i
couldnt believe this..but with my cycling background i remember elliptical
chainrings and such which effectively changed gear while pedalling. i
simply chipped away all of the crud between the teeth and redid the timing.
the engine fired on the first rev and idled well, whew. btw the crud was
the same colour as the normal between the teeth colour and so was not
readily seen. i knew that the belt wasn't slipping because when turning the
engine by hand i could watch the cam pulley for any change or halt in
motion and there was none...but still the timing changed. definitely needed
a drink after that one! btw the compression is still good so a cold mc
engine does not contact the valves. when in the fault condition it cranked
as if the valves were bent or burned...there was no compression because the
valve timing was so far out
mike