timing suggestion for EL (1950)

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Excalibur
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Re: timing suggestion for EL (1950)

#16

Post by Excalibur »

awander wrote: Sun May 27, 2018 2:12 pm TDC would occur when the mark is further to the Left.
Correct. I think I see the confusion. To clarify, perhaps better I said: "TDC mark is further to the right as it has not yet come into view".

Moving crank in direction of rotation, full advance mark would then move to the left and tdc mark (if so equiped) would appear.
I think we've got this. It's a bit of a brain teaser.

Probably the best way anyone could clarify this for themselves is to strobe the mark while manually advancing/retarding the timing control back and forth. Quickly you'll see which which way the mark moves.
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Re: timing suggestion for EL (1950)

#17

Post by devon john »

before the fly wheel mark is advance after the mark is retard ,,


john
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Re: timing suggestion for EL (1950)

#18

Post by RUBONE »

The crankshaft is turning counterclockwise when viewed through the hole. As the mark just begins to enter the rear of the hole is the most advanced position, the crankpin furthest from TDC. As the mark moves through the hole from right to left the mark shows a more and more retarded situation, as the crankpin becomes closer to the centerline and TDC.
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Re: timing suggestion for EL (1950)

#19

Post by Excalibur »

To clarify the confusion..
If the points open when the flywheel mark is here, timing is about 36°BTDC
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Re: timing suggestion for EL (1950)

#20

Post by Excalibur »

If the points open when the flywheel mark is here, timing is about 32°BTDC. The flywheel has moved 4° CCW and the piston has moved up the cylinder slightly, perhaps a millimeter or so.
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Re: timing suggestion for EL (1950)

#21

Post by Excalibur »

If the points open when the flywheel mark is here, timing is about 28°BTDC. The flywheel has moved another 4° CCW and the piston has moved up the cylinder slightly, perhaps another millimeter or so.
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Re: timing suggestion for EL (1950)

#22

Post by Excalibur »

OK. Let's get this right. It's too important to mess up on timing. Our motors are too valuable. Can anyone correct or improve these illustrations?
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Re: timing suggestion for EL (1950)

#23

Post by Andygears »

My old timer advise always was "A Harley will run good with the timing 20 degrees either way, it won't be noticed because of the low RPM nature of Harley's, It will only be noticed when starting". Mostly meant to say it won't start well unless the timing is right. Ideal timing, in my opinion, depends on the individual motor, cu. in., exhaust, carb, etc., but at the end of the day you are faced with two settings, 4 degrees apart, I haven't known anyone using the forward position.

Just my two cents.
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Re: timing suggestion for EL (1950)

#24

Post by nan00k »

'bin biting my tongue, but isn't a lot of the confusion regarding advance / retard arising because when looking at the flywheel mark you are 'advancing' the timing mark across the window and this is confused with setting the points to the mark which retards the spark further up the stroke towards TDC as the timing mark travels across the window.

just sayin'.
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Re: timing suggestion for EL (1950)

#25

Post by Andygears »

Let's not confuse proper point gap with "effective timing". First, the mark on the circuit breaker is a guide to get in the ball park. Many circuit breakers for other engines have different or no mark at all. What is important in the circuit breaker is the point gap, and the gap is engineered to match the point cam profile to create full coil saturation when points are closed, then just as they open, the condenser then "condenses" the last bit of high voltage electricity, makes a point spark and with the points no longer making ground, the coil takes the next best path to ground, the spark plug! So with this in mind, the point gap is a constant when points are new and parallel, circuit breaker bushings tight, point cam has accurate profile, point plate not bent, etc. This is why point gap should be set prior to timing adjustment. As the rubbing block on the points wears down, the gap gets smaller and the points open later. Think about the 360 degrees of crank revolution, now imagine scribing 360 lines on the end of the point cam, now pick out the one that gives you the proper timing, impossible huh? So we don't time off the point cam with a circumference of,? maybe 3/4 of an inch. We time near the circumference of the flywheels, Pi (3.14) times 4+ (the mark is outboard of the crank pin) or about 3 X 5 or 15 inches! Now scribe 360 lines in 15 inches 15/360 or about .0416 inches per degree. So the 4 degrees of timing we've been referring to ( from the back of the hole to the center) is about .1664 or maybe 5/32 (.156) of distance.

If I haven't lost you by now, you should be able to see the futility of setting timing by point gap! The 4 degree range of different engines "proper" timing is much less than the wide groove engraved in the end of the point cam. All this said, it is imperative that the points be set first and correctly. Then with a ohmmeter or a cigarette paper, the engine must be rotated slowly and smoothly and the exact moment the points open, the position of the timing mark viewed with the circuit breaker fully advanced. If it's off, the side nut must be loosened and the slide moved and the process repeated until the points just open with the mark at the desired position in the window. Practice and repeat, see if you can repeat the exact position of the timing mark.

Once you have mastered setting the timing precisely, YOU should determine what position works best for your motor and riding style.

My 2 cents

Andygears
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Re: timing suggestion for EL (1950)

#26

Post by devon john »

thanks to all that replied ,,, my red faced engineer friend has now sent his apology and said everyday is a school day ,, and will now ajust his bike to the right settings !!!!

this is what the site is about THANKS AGAIN

john
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