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MO1L Ignition Timing

Good morning All,

A quick question regarding ignition timing.

I used the Hans method to time my ignition and managed to get the points opening at pretty much bang on 7/16" (fully advanced) BTDC.

Looking at the workshop manual, I'm assuming the " - " shown as the figure for fully retarded timing BTDC intimates it should actually be 'At TDC'.
What I've found is, setting the fully advance timing as near as I can, then checking the fully retarded timing, it will actually fire at approximately 2-3 degrees ATDC (sorry for mixing the two measurements, it's so minimal I struggled to measure it in a linear fashion).
I'll have another crack at it tonight with a DTI but my question is, if the mag does indeed advance / retard a little more than it should for whatever reason, which way would be the best (and safest for the engine) to set it up?
I'm guessing firing anytime after TDC really isn't desirable?

Mant thanks in advance,

Gino

email (option): gino_kerekes@yahooooo.co.uk

Re: MO1L Ignition Timing

Hi Gino...If you read the piece I wrote for the 'Technical Section' it explains why ignition advance and retard is needed and may help to clarify the principles of what is happening and why....

Regarding your question though, where the engine fires at full retard doesn't really matter as it is never run fully retarded...

The only thing that matters is the '7/16" BTDC fully advanced setting' as that is where the engine is operating at anything over starting/tick over/slow running speeds.
The retard setting is done manually using the lever and as such can be set anywhere from fully retarded to fully advanced as required...Ian

email (option): ian@wright52.plus.com

Re: MO1L Ignition Timing

Many thanks Ian,
Fully understand now!
Cheers,
G.

email (option): gino_kerekes@yahooooo.co.uk

Re: MO1L Ignition Timing

I have just read and also printed Ian's topic on ignition timing and will check my settings using those notes as reference. I am sure my engine timing is right as I set it when the head was off and measured piston position with verniers and checked a number of times. My bike starts easily with a bit of advance and runs on full advance without problem. I have set the idle speed at the retarded setting as when advanced the engine speed increases. That way my idle speed is set at a constant speed. I find it is easier to engage gear with engine idling at slowest speed at retard position. The engine will not pick up revs in this position and frequently stalls or back fires through carby, obviously because it is retarded. I did lift the carby needle one notch hoping a bit more fuel might cure that problem, but made no difference. It can be a bit awkward with clutch in and try and advance the ignition so that I can move off as both controls are on same side. Putting into gear in advanced setting with increased idle speed can cause a crunch of gears if not done very slowly.

email (option): tknalder@iinet.net.au

Re: MO1L Ignition Timing

Kim are you saying you retard the ignition to change or engage gear? Might be better to slow the tickover down a bit. Ron

email (option): ronpier@talk21.com

Re: MO1L Ignition Timing

Ron I do slow the engine down to engage 1st gear when stationary (retarded), not so on the move. What is the best position to set idle speed in the advanced or retarded position. If its set in the advanced position the engine would most like stall when retarded. What is the norm here.

email (option): tknalder@iinet.net.au

Re: MO1L Ignition Timing

Kim I always start with the pilot air screw 1 1/2 turns out. Warm the engine up and set the ignition to about 1/2 retard and set the throttle stop screw to a slow tickover, then screw the pilot screw in or out at 1/4 turns to get any raise in tickover speed. Then adjust the throttle stop again to the desired slow tickover. Of course it's all nice in theory when everything in your carb/engine/ignition is perfect.

A slow tickover at full advance will often be a bit lumpy as the ignition is happening before the piston has reached TDC and is effectively trying to be forced backwards......Which is what happens when you get a kickback when trying to start the engine on full advance.

Your crunching when engaging gear might be more to do with your clutch or its adjustment?

Ron

email (option): ronpier@talk21.com

Re: MO1L Ignition Timing

Thanks for the tips Ron, I will give it a try. At the moment it is pouring rain so shed can stay locked.

email (option): tknalder@iinet.net.au

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