Timing


Information and questions on GL1000 Goldwings (1975-1979)
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zach75gl
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Joined: Tue Dec 06, 2011 7:18 pm
Location: texas
Motorcycle: 1975 gl1000

Timing

Postby zach75gl » Wed Jan 11, 2012 6:36 pm



How do I check the timing on my 75 GL 1000?



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virgilmobile
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Re: Timing

Postby virgilmobile » Wed Jan 11, 2012 6:54 pm

There's a bunch of write ups about this.I've found a auto type strobe and checking in the site hole works well.other methods work as well including just a test light on the points.Whichever you do,if you need to adjust them,use the "split the difference"method.

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Fred Camper
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Motorcycle: 1977 GL1000, 1976 LTD GL1000

Re: Timing

Postby Fred Camper » Wed Jan 11, 2012 7:26 pm

You must split the difference if you want it to run like it should. Good write ups on Robert Overby's method if you search. Virgilmobil is spot on yet again.

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scotterichmond
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Re: Timing

Postby scotterichmond » Thu Jan 12, 2012 11:29 am

This is what I do

When you set the static timing for cylinder #1 and #2 relative to the F mark for "1" on the flywheel by adjusting the main breaker point base plate, you need to be aware that Cylinder #1 (compression stroke) will fire (just as the 1-2 points open) about 2 - 5 degrees BEFORE Cylinder #2 will fire when the same set of points open the very next time (180 degrees of camshaft rotation and 360 degrees of crankshaft rotation). By carefully observing your test light, ohmmeter or buzz box while rotating the engine through several revolutions you will be able to determine the degree of variation you have on cylinder #1 and #2 timing. Here's how to judge: 5 degrees of timing equals about ½ inch on the flywheel...5 degrees is also the distance between the "F" and "T" marks. Move the base plate so that you "split the difference"…one cylinder will be a little early and one will be a little late. You don't really need to keep track of which cylinder is early or late, just make certain that the "early" cylinder never fires more than 2 degrees before the F mark. If you just go "by the book" and don't follow the procedure described above, you can end up with 1 cylinder up to 5 degrees earlier than the F mark. This causes the low speed knock off the front of the engine many GL1000's exhibit. It's hard to recognize because it's actually a "spark knock" of an engine under no load, but only affecting 1 out of 4 cylinders. "Splitting the difference" is not a perfect solution, but it gives you an acceptable compromise with much smoother idle manners.

When you're done, set the timing for #3 and #4 relative to the F mark for "2" on the flywheel by moving the points sub-base (there shouldn't be any appreciable difference induced by "wobble" on this set).

Here's the second problem you can have, even when you carefully follow the workshop manual. The spec for breaker point gap is listed as 0.012" - 0.016." Without coaching, most people will aim for the middle (0.014") as a hedge against their less than expert skill with a feeler gauge. Again, I'll skip the theory, but if your point gap is on the smaller end of this range you can end up with a problem called "dwell overlap." Dwell is defined as the duration of time that the points are closed and the primary winding of the coil is energized.

Basically, you want to make sure that you never have both sets of points closed at the same time. If you do, the non-isolated nature of this design will allow a voltage drop that can dissipate the saturation of the second coil and cause a weak, unreliable spark.

Don't worry about the electrical engineering theory. Here's what you do. Aim for the "high" end and set the breaker gap at 0.016". Next set the timing per the special instructions above. Then using your test light, ohmmeter or buzz box rotate the engine through several revolutions (for each set of points). As detailed above, the points for #1 and #2 should OPEN at +/- the F mark for "1" on the flywheel. Now make an additional check to determine that they do not CLOSE until AFTER the F mark for "2." If they close early, you need more point gap which results in less dwell. Each increase of 0.001" point gap reduces dwell by about 4 degrees. Note, each time you adjust the point gap, you MUST reset the timing!

Once you're happy with #1 and #2, repeat the procedure with #3 and #4. In this case, the points for #3 and #4 should OPEN exactly at the F mark for "2" on the flywheel AND they should not CLOSE until AFTER the F mark for "1."

This all sounds complicated and I've described it in several steps and in more detail than I intended. In practice, it's quite simple. Here's all you need to do in a step-by-step summarized sequence:

1. Set the point gap for #1 and #2 at the max. end of the range (0.016")

2. Set the timing for #1 and #2 using the "split the difference" method relative to the F mark for "1"…early cylinder no more than 2 degrees before F mark for "1"

3. Check that points for #1 and #2 CLOSE after the F mark for "2"…if not increase gap, re-time and repeat this test

4. Set the point gap for #3 and #4 at the max end of the range (0.016")

5. Set the timing for #3 and #4 relative to the F mark for "2"

6. Check that points for #3 and #4 CLOSE after the F mark for "1"...if not increase gap, re-time and repeat this test

Once you get everything set correctly, minor maintenance is reduced to periodic cleaning and re-gapping of the points to the max. value. You don't have to futz with timing every time.

Point of clarification which confuses some people: The "1" and "2" marks on the flywheel do not refer to cylinder 1 and cylinder 2. Rather the "1" on the flywheel [and it's associated T (Top Dead Center), F (static ignition fire), and Full Advance marks] refer to all of these events for both cylinder 1 AND 2 and the associated set of ignition points for cylinders 1 and 2. The events are phased 360 degrees apart.

Likewise, the "2" on the flywheel [and it's associated T (Top Dead Center), F (static ignition fire), and Full Advance marks] refer to all of these events for both cylinder 3 AND 4 and the associated set of ignition points for cylinders 3 and 4.

Odd observation. I've worked on a few bikes that had the timing variation on cylinder #3 and #4 instead of the expected timing variation on cylinder #1 and #2. I have no explanation for this. The cure was the same…split the difference in timing on #3 and #4 with the early cylinder no more the 2 degrees before the "F" mark.

Another tip:

Contrary to some manuals, ignore the punch mark(s) on the eccentric breaker cam when setting points gap. They were not created very precisely by the factory and amount to an unnecessary distraction. Just aim for the highest point on the cam lobes and then set the points.

Final tip:

To avoid the unnecessary distraction of a test lamp that alternates between bright, dim and off - put a small piece of paper (like a section of business card) between the points on the side you are not adjusting. This will allow your test lamp to have only 2 modes: bright and off. Without this step, the activation of the "other" coil will make your test lamp dim in a distracting fashion.

punch
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Joined: Tue Apr 30, 2013 1:28 am
Location: lake elsinore California
Motorcycle: 1979 gl 1000

Re: Timing

Postby punch » Wed May 01, 2013 12:49 am

do I have to have power to the ignition system and heat up everything . Cant you static time and find the position of points opening relative to the flywheel by just checking continuity with the ignition unpowered? please enlighten me I want to fire my 79 gl 1000 tomorrow . new condenser and points in place . thank you , Punch

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Fred Camper
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Re: Timing

Postby Fred Camper » Wed May 01, 2013 5:14 am

Points are a mechanical system so you can do a lot with the ignition off. In fact you can ruin a coil if you let it hang in one position too long. So it is a good idea to gets most of the way with ignition off then check one time to confirm with ignition hot.

punch
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Joined: Tue Apr 30, 2013 1:28 am
Location: lake elsinore California
Motorcycle: 1979 gl 1000

Re: Timing

Postby punch » Wed May 01, 2013 7:54 am

Thank you , I am matching the f marks to point opening position ,right?

punch
Posts: 3
Joined: Tue Apr 30, 2013 1:28 am
Location: lake elsinore California
Motorcycle: 1979 gl 1000

Re: Timing

Postby punch » Wed May 01, 2013 7:54 am

Thank you , I am matching the f marks to point opening position ,right?

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Fred Camper
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Location: Metro Detroit, MI
Motorcycle: 1977 GL1000, 1976 LTD GL1000

Re: Timing

Postby Fred Camper » Wed May 01, 2013 11:55 am

You better read Scotterichmond's post a few times first. Plenty of detail above and if you want it more simple, a Dynatec electronic unit is your answer.




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