Author Topic: T6 Ignition Timing  (Read 296 times)

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Offline PaulW

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T6 Ignition Timing
« on: 11 Apr 2019 at 18:31 »
Having measured my ignition timing with a pointer on the front cylinder, I believe my ignition is significantly too far retarded.

I've checked the seating of the contact breaker in the BTH magneto and the taper key is sitting correctly in its groove on the end of the armature. At the drive end of the magneto, the peg unit is on a woodruff key, so cannot be moved on the armature taper.

So, if I'm not mistaken, that only leaves the magneto driving gear with its slot... and the idler gear that drive that.  In the photo below, the piston is at top dead centre.  Can someone advise if that slot looks to be in the correct place?

Many thanks

Paul


Offline eddie

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Re: T6 Ignition Timing
« Reply #1 on: 11 Apr 2019 at 19:39 »
Paul,
         If all the keys in the mag drive are in tact, the timing has probably been upset by someone allowing the small idler that drives the generator to drop out. You should be able to re-time the mag by the same method.
        Replace the magneto and set the crankshaft to TDC with the valves rocking on the REAR cylinder, then back it off and bring it up to 36 degrees before TDC (one tenth of a turn). Remove the generator and drive sleeve from the timing cover, and carefully withdraw the small idler until it comes out of mesh with the timing gears. Now turn the magneto until the points are about to open and it is firing on the FRONT cylinder with the mag fully advanced, then push the small idler back into mesh. Try rocking the crank back and forth to confirm the timing is correct. Replace the generator and it's drive sleeve before trying to start the engine - it is only the generator that keeps the idler in place!

  Regards,
                 Eddie.

Offline PaulW

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Re: T6 Ignition Timing
« Reply #2 on: 11 Apr 2019 at 20:02 »
Many thanks Eddie...I'll give that a go.