06-01-2017, 08:50 AM
"So I guess the way to adjust the timing would be to vary the position of the coil relative to the flywheel. But to measure the timing you would have to calibrate the flywheel, then run the engine with the shroud removed and check it with an inductive timing light"
EXACTLY THAT.
except the engine need not be running to set timing.
i never used to bother with setting up timing top dead center and was very comfortable with just using coil "sight marks" setting the coil for about forever.
but lately i've gone back to being precise.
mostly Scott K ruined my day pointing out some of the cranks are cut differently year to year
SteveO then further wrecked my day showing the typical flywheel variance allowed in factory tolerances back in the day.
With most of the motors being of unknown Factory Original Purity there is an excellent chance any motor new to you could be a composite of years and parts.
Since Mcculloch changed flywheel timing slots and timing keyways on cranks it is possible to make a really badly timed motor.
So any method of timing that doesn't determine top dead center of the actual motor , as currently assembled ,may result in a poorly running motor.
Occasionally that can ruin a piston ,or more likely , wreck your weekend of fun driving with endless bad starts.
to set and or determine top dead center and set your timing precisely you want to build a little dohicky out of a used spark plug and bolt.
the bolt will go through the spark plug body and be adjustanble.
once you've determined top dead center for the engine you can easily set timing using a cheap plastic compass.
i think it was scott that posted exactly how in a thread that now is somewhere in the old forum copy.
it'll be a little hard to find but i'll take a look.
i'm pressed for time right now but i'll dig up the thread about setting timing on a two stroke later on this week..
EXACTLY THAT.
except the engine need not be running to set timing.
i never used to bother with setting up timing top dead center and was very comfortable with just using coil "sight marks" setting the coil for about forever.
but lately i've gone back to being precise.
mostly Scott K ruined my day pointing out some of the cranks are cut differently year to year
SteveO then further wrecked my day showing the typical flywheel variance allowed in factory tolerances back in the day.
With most of the motors being of unknown Factory Original Purity there is an excellent chance any motor new to you could be a composite of years and parts.
Since Mcculloch changed flywheel timing slots and timing keyways on cranks it is possible to make a really badly timed motor.
So any method of timing that doesn't determine top dead center of the actual motor , as currently assembled ,may result in a poorly running motor.
Occasionally that can ruin a piston ,or more likely , wreck your weekend of fun driving with endless bad starts.
to set and or determine top dead center and set your timing precisely you want to build a little dohicky out of a used spark plug and bolt.
the bolt will go through the spark plug body and be adjustanble.
once you've determined top dead center for the engine you can easily set timing using a cheap plastic compass.
i think it was scott that posted exactly how in a thread that now is somewhere in the old forum copy.
it'll be a little hard to find but i'll take a look.
i'm pressed for time right now but i'll dig up the thread about setting timing on a two stroke later on this week..
Dave L.