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1990 Rmx250 Ign Timing

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Sep 12, 2014
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#1
Good Day All

I have been looking for help with my RMX250, Its got a racing Magneto set that doesnt use a woodruf key to lock it into position, I have it currently set to 1.8mm btdc, and it starts and runs ok, but Id like to know if this is actually the factory settings or if someone can help me out with factory settings, in either BTDC or mm btdc ??
 
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#2
Or if someone can pull the spark plug out of one of theirs and measure how many mm btdc on their stock unit?? I'm tempted to set the timing to 7.5 degrees btdc but when i set the timing initially it measures up to around 15 degrees btdc?
 
- a d v e r t i s e m e n t -

Joined
Mar 8, 2008
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#3
Can't really help you out with it as I don't own that bike. If it runs OK I'd try to advance ignition about 5mm or retard timing for the same amount, seeing that way if it becomes better or worse. Turning clockwise retards, and counter clockwise advances.

To retard the timing, simply remove the timing cover, slowly kick the engine over and watch which way the flywheel is spinning. Then turn the stator plate in the opposite direction.

To advance the timing, go in the same direction as the flywheel turns. Thanks to zig06 :)
 
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#4
Hey Arengo, I found the bike at liek 15 degree btdc and found in a clymers manual that the timign should be at 7.5 degrees btdc at 9000 rpm, ( but the bikes never had advance/retard timing?? ) so i set it to that as base, have yet to fire her up and test though ( bit of a pain in the arse to alter the timing on these keyless magneto's! )
 
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#5
I can imagine, be aware that some aftermarket crank shafts have a reputation to come with an advanced timing which in turn could throw off your calculation. How is that magneto fixed? With no Woodruff key?
 
- a d v e r t i s e m e n t -

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#6
Its a stock Crank, only the magneto and rotor are after market, the rotor it a press fit on the shaft itself