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#868418 01/08/22 1:02 am
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DAMadd Offline OP
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As posted in a primary chaincase thread my inherited A65t project is winding down but it wouldn't fire. Sooo, in going thru my process and rethinking and searching the forums for tips and tricks BEFORE asking stupid questions that 900 people have already answered. I happen to see so4mething about anti clockwise vs clockwise on a Boyer. Well having only the experience of my TR6 to go on (and nothing in the BSA manual about it) I just figured if the ignition was on the right side it would be clockwise. I had never really specifically looked for a left side points case on the myriad bikes I've seen, didn't seem important. Well, come to find out... 😂 they can run anticlockwise when it's on an idler! Explains why it wouldn't fire. Snowstorm activities prevented me from correcting that today but maybe tomorrow or Monday. There could be a few other issues but I'll wager having it timed completely backward could be a place to start corrective action.


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Timed 180 out before.

Just thinking out loud, sorta, A65 when viewed from timing side:
Rear wheel rotates clockwise under power.
Drive sprocket rotates clockwise.
Main input shaft to trans clockwise.
Drive side sprockets clockwise.
Crank clockwise.
Idler driving cam which has the ignition points and auto advance, counter clockwise.
Swap the wires at the coils instead of retiming for a quick check. On an old V-8, rotate the distributor 180.

Which segways into other timing stuff:

1) What is the stock non-advanced ignition timing? Asking because if my leg has to provide the input for rotation to start the beast, would it not be good to have the timing after TDC? Say 5 degrees? Leg rotation speed is slow like 60 rpm, right? Maybe a few degrees more to account for the slack in the mechanics.

2) On an electronic ignition, would it not also try to fire at this same stock timing assuming it uses the stock auto advance mechanism? Then after it fires up adjust the curve to it's internal program according to speed? Perhaps, discounting the mechanical advance at some point? I would guess that todays electronic circuits might be sophisticated enough to look at the rate of change of the speed and take advantage of the particular engine's characteristic even without a throttle position sensor. Which segways into...

3) If an EI were to be programmed to any particular application, would it not be advantageous to have it extract energy values at any moment and advance or retard spark?

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Triumph twins are clockwise because the point are on the cam. The A65, as you found out, are on the intermediate gear.
Stock timing, if I remember right is 34 degrees BTDC full advance. The retarded timing depends on whether you have ET ignition or battery type ignition. ET retard is only 10 degrees at the crank. battery ignition is 24 degrees.
Swapping the coils wires will not fix late timing due to assuming the wrong rotation direction of the point cam.
To get the engine to run with 5 degrees ATDC timing would require opening the throttle from the idle setting since there would not be enough power to get it through the next compression stroke.
EI ignition would only fire at the stock timing if it is just a switch replacement for the points or it was programmed to the same timing. Fully electronic ignition does not use a mechanical advance mechanism. The ones made for these bikes are fairly simple with only RPM as the input. A more advanced ignition would have intake vacuum and temperature, engine temperature, barometric pressure, throttle position and a knock sensor.
Even the simple RPM only type could be better by adding an RPM stabilizer that automatically adjusts the timing at idle.

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DAMadd Offline OP
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It is a Boyer mk 3 so that would fall into set electronic curve only catagory. Had I put the timing case together I MIGHT have noticed the points were on the intermediate gear and put together that it turns anticlokwise but even that is unlikely, just glad I didn't start tearing it down before at least getting static time in the ballpark.. Once more kudos and thanks to the knowledge base here! Had I not been down the wormhole reading 10 year old threads I would have put the work off for a while.. it's 16 out in the non heated garage today. Have a little space heater but 16 is hard to overcome. If it gets up near 30 I'll give it a go. Just using the advance timing slot on the crank with the tool for the initial setting as per manual.. Among the documentation was a card indicating a megacycle cam, so I was hoping it's near enough to stock as to not effect the timing curve. To what purpose the PO had for that eludes me. I knew him well and he didn't race or anything so hoping that's mild performance.

(Edit that's -8 c to about 1 in the above temp references for those across the pond)

Last edited by DAMadd; 01/08/22 7:04 pm.

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Interesting thread. The tool should get you darn close and then you can use a light to check the timing. Do you know what Mega is in there? Would be a good thing to know. I'm kind of in the same boat right now. Got my newly re-assembled Hornet out for a run up n down the street. Made a bunch of adjustments and then it got cold here in NJ as well! Patience Grasshopper. Cheers, PRT


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