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Back in 1987 I had a Honda C50 where the points plate for some reason would not move so I set timing by adjusting the point gap (I think the screws holding the plate were rounded out philips heads which I could not get loose). I have a Clymer manual explaining the points adjustment.
From an engineering standpoint though I dont like the dependency on this 0.018" and 0.019" lift height for both lobes needing to be equal. If this is wrong I will put a dynatec or something like that in.
I am also an electronice engineer with microprocessor and some high voltage experience, I like the idea of trying to build an electronic ignition with microprocessor based advance, maybe a slotted disc with optical pickups... But this would be a long term project, and I want this sorted by next spring.
I want to again clarify my post. Years ago, I had a 1976 FXE with S&S 84" stroker kit, Andrews "B" grind cam. This was long before the internet and access to a lot of experienced folks handy. I am very rural, but we did and still have a Harley dealership. It was new back then; now it is one of the older ones still around.
One day we were in the shop and the owner overheard me telling someone that my bike ran good but would only properly time on one cylinder. You could never get both timing marks in the window. Your timing marks are undoubtedly different than a 1976. Another thing was my Points were never close to having the same gap for the front and rear lobes. The owner was the mechanic and he said Bullxxxx I can time it right. Well he worked on that for hours, even long after closing time. I was getting nervous about what it was going to cost and he said don't worry about it, I know I can time this thing. Well long story short he couldn't do it either and charged me like $15.00!
A few years back, with the help of the Internet, either on a forum somewhere or YouTube, there was a similar problem / solution posted. I do not recall exactly how to do it, nor do I remember the proper point gap, (that .018" was an example for here, nothing else) but the fix was you installed and adjusted the point gap and checked both lobes gap. If it was off you took a mallet and tapped the center bolt one way or the other until the gaps got equal. I do not remember which way you tapped to, the wide side or the closer side. I should have that written down somewhere, but don't know where. I did that on this 1984 FXEF when the original electronic died and I went to points as it was much cheaper and I wasn't made out of money, and it did work. Since then I went to Ultima digital, programmable and haven't looked back! I am certain that would have allowed my 1976 FXE properly time.
Back in 1987 I had a Honda C50 where the points plate for some reason would not move so I set timing by adjusting the point gap (I think the screws holding the plate were rounded out philips heads which I could not get loose). I have a Clymer manual explaining the points adjustment.
From an engineering standpoint though I dont like the dependency on this 0.018" and 0.019" lift height for both lobes needing to be equal. If this is wrong I will put a dynatec or something like that in.
I am also an electronice engineer with microprocessor and some high voltage experience, I like the idea of trying to build an electronic ignition with microprocessor based advance, maybe a slotted disc with optical pickups... But this would be a long term project, and I want this sorted by next spring.
The MoCo beat ya to it... In about 1982...
and the little honda responded to gap Change because someone had already put the timing Plate close to the correct spot...
SBR Mike: I have never even seen a second Timing mark!! I do Know certainly that the Timing is 45 degrees apart Exactly..
To Be Scientific
the Firing order is;
Front Cylinder Fires, 315 degrees later - Rear Cylinder Fires, 405 degrees Later - Front Cylinder Fires, 315 degrees later, - Rear Fires, ETC
On Points system it is desireable to Ensure that the gap at Full Open points, is at least close to the same, Front lobe and rear Lobe, Identical would be ideal.. with EI this is generally not a Factor... tho some do provide for slight variations in Rear Cyl Timing..
We Can Re-Think, and even re-Engineer... Or... We can set it Up like it was Engineered to Be... and Go
At the Race track... looking for half a tenth in a 1/4 of a mile???? Maybe and that is a Huge Maybe, we can do better... Doubtful tho...
Last edited by Racepres; Oct 20, 2020 at 08:35 AM.
There was a vertical line and a dot. One was for front cylinder and one was for rear cylinder. Ideally you would see the dot centered on the line, centered in the hole with a timing light at a specified RPM. Some folks would put the line to the front or rear of the window and the dot somewhere else in the window, I don't remember exactly which did what. But you had to have the bike at a certain RPM and as you moved the breaker plate you would move the timing marks throughout the window.
That was from years ago. The S&S wheels had the same timing marks as O.E.M.
There was a vertical line and a dot. One was for front cylinder and one was for rear cylinder. Ideally you would see the dot centered on the line, centered in the hole with a timing light at a specified RPM. Some folks would put the line to the front or rear of the window and the dot somewhere else in the window, I don't remember exactly which did what. But you had to have the bike at a certain RPM and as you moved the breaker plate you would move the timing marks throughout the window.
That was from years ago. The S&S wheels had the same timing marks as O.E.M.
from my 1982 book.. i think the advance timing marks at 2000 rpm are what I will use. I will look if my advance weights etc are ok, and then to be sure the 315-405 story is correct go with a Dynatec instead of the much more scetchy option of trusting the lobes are equal height. Will definately not use the big persuader to whack them into submission. I think anyway over time the lobes will wear down and become unequal...
the original igintion is microprocessor based... I work in microelectronics and know that the chips are only made for a lifespan of 10 years. Using 40 year old microelectronics, well, just make sure your mobility insurance is up to date (dont know if this exists in the US, but here in Europe this insurance tows your vehicle home with no cost to you)
My '79 has the Original Prestolite...and The '82 has Stock as well...only with an Ironhead black box.. I ain't Skeert..
Never even looked for a Rear cylinder timing mark... with most Ignition Systems... the System cannot separate the two Anyway..
I'm sitting here thinking you should try one of the old Single fire points systems... I hated them..
OP this is not your timing marks, these are for 1970-1977. I know folks here are no fan of Clymer manuals, but that is the only "older" Shovelhead book that I have anymore. Item number 4 references figures #80 and 81. My memory surprises me from time to time. That little story about the dealer trying to time my bike was from 1988. I sold that bike in 1990. As I recall, there is the large "Dot" that you see in the pic for timimg light purposes and if my memory is also correct there is a smaller diameter "Dot" that is for something else and is not to be confused with the larger "Dot" when Timing with a timing light.
To clarify the tapping on the bolt head that holds the advance unit on, if the gaps were say: .018" and .033" you tap to equalize the reading, say, it ends up .023" and .024", then you gap the points to the proper spec.
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