Timing by kickstart or stator bolt?

[NYSingh]

I was double checking my timing, and I noticed that the timing differed depending on whether I was turning the crank using a wrench and turning the stator bolt or pushing the kick starter.

Using the stator bolt, it was just a bit off 2.0 BTDC. Using kickstart it was about 1.7 BTDC. That seems like a not insignificant difference. I did not touch the timing plate at all in between the two checks. Note that I'm using the Vintage Smoke Dyna.

Why is that the case? Which method is the proper one for setting the timing?

See video (you have to listen for the 'snap' of the spark):

Also, just before this video I checked using the stator bolt and it was almost bang on 2.0. 1 min later, without touching the timing plate, again checking w the stator bolt, it moved to ~1.92. How in the world did it move without touching anything?

[Striker1423]

Either your gauge is moving. Or you aren't accounting for potential crank slop.

Ensure your gauge isn't moving. You won't see it, but if you can grab the gauge and move it, it isn't secure enough. Then, rotate the crank 3mm clockwise before taking a measurement and your desired BTDC mark. This accounts for any potential slop in the crank bearings.

But the very best way is to ensure your timing marks line up at stock, then time the bike after your initial setting with a timing light.

[1976RD400C]

I wonder that if when you put a wrench on the rotor bolt, and turn the key on, that the wrench becomes magnetized and throwing off when the pick-up fires because it is in close proximity.  As mentioned, a timing light is the hot ticket to see what is actually happening while it is running.

[Dvsrd]

I wonder that if when you put a wrench on the rotor bolt, and turn the key on, that the wrench becomes magnetized and throwing off when the pick-up fires because it is in close proximity.  As mentioned, a timing light is the hot ticket to see what is actually happening while it is running.

Also, a timing light will show if timing is unstable due to worn main bearings, especially with a points setup.

[NYSingh]

Re-reading Nick's instructions for the Dyna, he says "Note: DO NOT use a screwdriver, wrench, or socket on the trigger bolt to turn the engine over. Either use the kick starter or raise the rear wheel off of the ground, put the bike in high gear, and use the rear wheel to rotate the engine. Using the trigger bolt to turn over the engine can either loosen the trigger bolt or cause a change in the timing."

So that answers that question!

Re the timing light - I'll have to order one. I'm sure this is a stupid question, but how do you actually use it? The youtube videos I watched always have a mark on a fixed point and a mark on the stator that spins.  In RDs, the stator is fully covered so there's nothing visible that spins except for the stator bolt (and the trigger that goes on it that came with the Dyna kit). So to check the timing with the light, would I (1) set the timing to 2.0 using the dial gauge, (2) put a mark on the timing plate at a position lining up with the mark on the trigger (which already has a mark on it), (3) use the timing light to make sure those marks are aligned when the light fires?

[m in sc]

theres a mark(actually one per cyl) on alt the rotor, and under the brushes is a scribe mark on the alternator casing.  run bike, point light at window under brushes, you'll see it.

[Dvsrd]

I would recommend to first verify the timing marks with the dial gauge, and maybe make a second  mark on the housing, for later timing . Then use a timing light (strobe) on a running engine to verify actual timing.

[SUPERTUNE]

RD400's have an adjustable pointer with a screw and pointer is slotted. Use your dial gauge set to 1.9mm and set the pointer to match mark on the rotor, then use a timing light to verify at 3-4k rpms.
Chuck