Topic: Timing Light Check with Modern Electronic Ignitions?

[BenelliSEI]

In the past year, I’ve installed two electronic ignition systems. The first was a ELECTRONIC SASCHE on my Benelli 750 SEI (just like working on a Honda cb550 with two extra cylinders). More recently, an older (but new) optically triggered C5 unit that included coils, wires and plugs. Came with some stuff I bought, so I’m trying it on my ‘75 cb750F. Both installations require setting the engine to TDC and removing the stock advancer plate. The trigger mechanism goes on and then rotated until the correct LED comes on the plate. Tighten it down and you are done.

My issue is that without the advancer plate, there is no where to shine my timing light and check idle advance and total advance (at idle and +3,000tpm). The Benelli has a crankshaft end sticking out the other side, so I was able to make a “clamp on” degree wheel and then bolt on a fixed pointer. Now I can physically check what the electronic advance is actually doing, with my timing light, while the engine is running.

Curious if anyone else has used a C5 and figured out any temporary or permanent way to check this, on a SOHC CB750. It bugs me to have to “assume” everything is working as it should! Suggestions appreciated.

[scottly]

You are correct that there is no way to verify ignition timing with a strobe light with a C5, AKA Power Arc ignition. I was first made aware of these systems about 5 years ago when one failed on a member's bike with less than 1000 miles. As the original advance plate was left at home, the suggested static timing was performed with a soda straw in the spark plug hole to determine TDC, which was probably only as accurate as +/- 5*.
The replacement failed the summer of 2017 while en-route to the family reunion in CO, in nearly the same spot. However, this time Matt had a spare points setup and was able to replace the POS Power Arc at the side of the road, and continue the trip.

[BenelliSEI]

Mmmmmm. I’ll be carrying the advancer and points plate as “spares”! I set TDC and then took off the LSide cover, bottled on a pointer and marked it there to make sure the unit was accurately set. But....... after that I have no way of checking up on it. Not a great design. It does seem  to work very well, instantaneous starts and clean running.

[Bankerdanny]

Mmmmmm. I’ll be carrying the advancer and points plate as “spares”! I set TDC and then took off the LSide cover, bottled on a pointer and marked it there to make sure the unit was accurately set. But....... after that I have no way of checking up on it. Not a great design. It does seem  to work very well, instantaneous starts and clean running.

The Martek 440 on my 550 failed while I was on a 2 week trip in 2017. Fortunately I was able to limp to TwoTired's place in Arizona and he lent me a point setup. I am going with points and the HondaMan ignition in my 750. I got the setup a couple weeks back and am just waiting for time to install.