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ignition timing?

ullose272

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i got a new motor for my sled so im transfering the mag and everyithing. should i just set it where it was in the old motor or what? i suspect the slots in the mag are how you adjust the timing?
 

retiredpop

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In the timing specs it should give a figure in thousands of an inch BTDC for timing the engine. Put the dial indicator in the mag side sparkplug hole, find TDC and zero indicator gauge, then rotate the engine backwards a bit then forward until you get the proper thousands of an inch BTDC indication on the gauge. The marks on the flywheel and housing should line up at that point. Rotate the stator and tighten. If you have a timing light made for 2 strokes then you can use it to check the timing at the operating rpm. Most automotive timing lights are incapable of flashing at the ignition pulse speed found in 2 strokes.
 
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rmk727

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Just from the sound of your question and responce and not knowing your ability and knowledge, call a dealer and take him the parts in a box and ask him to put the case halfs together and set the timing. Were you a young guy and the case clean I would do it for around $25.00, just ask; a good dealer will work with you
 

ullose272

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im pretty mechanicly inclined, ive built muiltiple 4 stroke motors. just never a snowmobile so i wasnt sure. im pretty sure i can figure it out. thanks tho
 
J

JohnnyH

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In the timing specs it should give a figure in thousands of an inch BTDC for timing the engine. Put the dial indicator in the mag side sparkplug hole, find TDC and zero indicator gauge, then rotate the engine backwards a bit then forward until you get the proper thousands of an inch BTDC indication on the gauge. The marks on the flywheel and housing should line up at that point. Rotate the stator and tighten. If you have a timing light made for 2 strokes then you can use it to check the timing at the operating rpm. Most automotive timing lights are incapable of flashing at the ignition pulse speed found in 2 strokes.

So you adjust the Stator before you check the timing with the light ???

Do you just use the dial indicator to verify that the timing marks on the flywheel are in the right place ?
 

ullose272

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yea you would have too cause all that stuff has to be on before you start it and the stator is behind all that crap.
 

retiredpop

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So you adjust the Stator before you check the timing with the light ???

Yes you adjust the stator so the marks line up when the piston is at the specified distance BTDC. After you tighten the stator at that position then you put it all together and check with a timing light if you have one that will work. Otherwise you just assume the pulses that come from the stator trigger the CDI at the proper time and therefore the timing is correct when it is running.


Do you just use the dial indicator to verify that the timing marks on the flywheel are in the right place ?

Yes and no. You need the marks to line up when the piston is at the proper distance BTDC and it is important to know that the marks are at the right place if you use a timing light because that sets the reference point. But if you had loosened the stator then you use the dial indicator to line up the marks. A small bit of piston travel changes the relation of the two marks to each other quite a bit so you have to be very precise.

Think of the timing as being two separate but related functions. The first is the relation of the stator to the crankshaft (static timing) which is set by lining up the marks at a certain point in the crankshaft rotation--given as a distance BTDC. The second is the CDI unit taking the pulses from the stator and varying the spark at different rpms (dynamic timing). The dynamic is part of the programming in the CDI.
 
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