Set the timming

I haven't posted for a while, the Christmas season and just plain laziness is to blame. I received some kind words about my blog from members of the Old Ski Doo Forum and it's motivated me to update my progress.

Really close to finishing, good thing because there's a ton of snow and I seem to be the only one not on it.

Set the timing today, I was worried about this because I thought it would be to technical for me, I was wrong, Bones on the forum held my hand all the way through it and I realized that it's not so scary.
Here you can see the stator plate with the lighting, brake and generator coils, the funnel shape on the crank shaft is the breaker cam, this is what opens and closes the points, to set the point gap, take the fly wheel and breaker cam spring off, slip the cam back on the shaft, now spin the cam on the crank until you see the points open, continue spinning the cam by hand until you see the points close, now spin the cam to the position approx. in the middle between start open and close when the points are fully opened. this is where you set point gap.


Now to set the gap on the points, in this picture I have the feeler gauge in the point between the contacts, just to the right there is a screw, loosen this screw then tighten it when the correct gap is set, on mine and most single rotaxes it's .16 of an inch.


Now your ready to put the flywheel back on, In the above picture I've place the breaker cam where it should be located, the 2 small tabs on the cam must fit into the advance lever, this is the lever with the large screw attached to the flywheel, this lever is spring loaded and will advance the timing when spinning at high revolutions centrifugally,

Once you've installed the fly wheel back on it's time for the timing, I bought a tone tester but found it useless the best and easiest way is to take a light bulb, this case my head light, attach one wire to the wire comming from the points to the ingnition coil, mine was blue, the othe wire from the light bulb to the positive post on the battery, then ground the battery to the motor. When you do this the light will work, spin the motor, when the light is dull the points are opening when the light is bright the points are closed. To set the timming You must have the piston at Before Top Dead Center (BTDC), for my motor with the 1971 TNT 292 cylinder and piston it's between 3.55 and 4.06 mm, with the points beginning to open.

I bought this dial gauge and magnetic stand, first find the highest the piston will go up or top of the stroke, this is called Top Dead Center (TDC).

Then spin the motor with you finger pushing down on the timing advance lever through the inspection holes on the flywheel so the timing is fully advanced. Pictured above (not so clearly) is me moving the lever to advance timing with a screwdriver, if you look into the large sloted hole to the left you can see the lever to push down. While pressing against the lever spin the motor, when the light goes dim and the points begin to open check the dial gauge. If it is not within the timing spec, mine are 3.55 to 4.06 adjust the stator plate, There are 3 set screws on the plate in sloted holes if the light dims before your within your spec turn the stator plate to the right to advance the timing, if the points open after or late, turn the stator plate to the left to retard the timing. Make sure you measure the BTDC while holding down the advance timing lever. I lost a few hours scratching my head over why I coulded get the timing right until I realized I wasn't advancing the timing.
After tighten the set screws on the stator plate, you should have a correctly timed motor, I was really pround of myself until I realized I had to pull the flywhell again to get the fan shroud on, No big deal, only 1/2 hour wasted. But the motor is timed!!