I have a dial indicator for the sparkplug hole in a 2 stroke but this thing is totally different. On the Triumph at least the older ones , they have a plug that resides behind the cylinders and at the front of the transition, the pre unit ( separate transition from the engine) don't have this plug, but this plug is removed and the tool threaded into the hole then a sliding pin goes into the tool... and goes down and touches the crank shaft weight that is the flywheel that is bolted to the cast crankshaft. this flywheel has 2 notches cut in it.
one for 38 degrees BTDC, and the other for TDC.... it is very accurate !
...more accurate than the magnet on the alternator.
it's just a fancy pipe plug with a hole drilled through it and a short rod fits tightly into the hole...no slop at all... so what you do is get the bike on compression stroke with the piston coming up , but way before TDC... and put the pin in the hole... put your finger on the pin and press a little...and rotate the engine slowly... when the notch comes around the pin will drop in the notch and you have the 38Deg. BTDC that you need to set full advance with. ....
but the Triumph has very little in the way of timing marks on it ...I am lucky to have one with needle in the primary cover that points to a line on the Alternator magnet.... but their not always accurate on these old bikes...
but checking it with the TDC tool it turns out this one is right on it. so that's good !
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the procedure for setting the electronic ignition was fairly simple, once you have the engine at exactly 38degrees BTDC you align the magnet with the stator plate that sets the timing, then tighten everything down and your done. but it is getting the engine to that place that isn't so easy...
... I suppose it is alot like any other bike you just line up the firing mark on the magnet and your there but it is different in quite a few ways.... one there is no TDC on the magnet at all just the firing mark.... I guess they figure for setting the valves that just past the firing mark is close enough to set the valves with..... LOL.... from what I've seen on the web most guys adjust them with the other side's rockers all the way down and that is close enough
so there is alot of misinformation on the correct way to do it and the manual is vague on the subject saying something like put the piston to TDC on the side your going to adjust and adjust both valves, but there is no TDC mark !!!
but You and I both know if you can get the piston on the compression stroke and at the top of it's travel that is close enough for government work ! LOL
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anyway, I got both carbs with their new jets back on the engine and had to give up and come back in the house and get warm again...
all I have left to do now is put the gas tank and seat back on and try starting it !.....
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then I'll need to set the airscrews on each carb and then time it with the strobe light.... and it will be ready to ride I hope.... we'll see.
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if I had a degree wheel I would have used that instead of spending $12.00 for the TDC tool cuz I'm cheap... but I've not replaced my degree wheel from the Ranch fire yet.... so the special tool got bought !
( I need a degree wheel anyway , I could use it on the lathe alot! )
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Bob........