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Author Topic: 74 CB750K Timing  (Read 773 times)

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Offline jprochnow

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74 CB750K Timing
« on: March 06, 2015, 02:10:44 PM »
The other day I adjusted the points gap to .014". Today when I went to static time it I found that while rotating the crankshaft clockwise point 1-4 makes before I get to the timing mark for 2-3. And 2-3 makes contact before I get to timing mark 1-4. Is this correct? But both are adjusted so when each reaches its "F" mark it breaks the connection. Any input would be appreciated.
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Offline jprochnow

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Re: 74 CB750K Timing
« Reply #1 on: March 06, 2015, 05:53:45 PM »
Maybe I didn't explain good enough. I will simplify it. When is the point supposed to make contact(close). I know it is suppose to open right at the "F" mark but when is it supposed to close?
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Offline scottly

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Re: 74 CB750K Timing
« Reply #2 on: March 06, 2015, 06:03:21 PM »
Don't worry about when the points close. ;)
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Offline chewbacca5000

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Re: 74 CB750K Timing
« Reply #3 on: March 06, 2015, 06:12:49 PM »
Quote from: jprochnow on March 06, 2015, 05:53:45 PM
Maybe I didn't explain good enough. I will simplify it. When is the point supposed to make contact(close). I know it is suppose to open right at the "F" mark but when is it supposed to close?

+1 It is when then open that matters.  As far as when it will vary depending on the year.  More total advance earlier years less advance latter years.  A function of the advance mechanism.
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Offline scottly

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Re: 74 CB750K Timing
« Reply #4 on: March 06, 2015, 06:17:10 PM »
The time the points are closed is the dwell, in degrees, and has nothing to do with advance...
« Last Edit: March 06, 2015, 06:27:24 PM by scottly »
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Don't fix it if it ain't broke!
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Offline jprochnow

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Re: 74 CB750K Timing
« Reply #5 on: March 06, 2015, 07:08:14 PM »
Ok I was confused as the points were shutting before well before I thought they should. For instance the 1-4 were shutting just before 2-3. So I thought to myself that it would be firing at that time... I did adjust everything a bit different then what was explained.

I moved the 2-3 plate to its center point. I turned the main plate to the mid point in the slots. I then turned the crank till the F mark on 1-4 was lined up. At that time I put my multimeter on the 1-4 point and checked continuity. I adjusted the point until it just broke contact right at the F. I then rotated the crank to verify that it lost continuity right at F. I then turned to the F for 2-3 and adjusted the 2-3 point till it just broke contact. Again I rotated the crank and verified that it breaks contact right at F on 2-3. After that I check points gap at 90 degrees to each F mark. Both were the same right at .012-.013. What do you guys think of this procedure?
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Offline chewbacca5000

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Re: 74 CB750K Timing
« Reply #6 on: March 06, 2015, 07:16:04 PM »
That is a good start, but a timing light makes this whole process much easier.
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Offline jprochnow

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Re: 74 CB750K Timing
« Reply #7 on: March 06, 2015, 08:11:02 PM »
I have one. That is what i'm going to attempt on sunday. I just did things a bit different as I set the open points prior to setting the gap. I figured the gap was controlled by the open point in relationship to the crank. So sundays plan is light timing and carb sync. Should I do timing before I do carb sync?
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Offline goldarrow

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Re: 74 CB750K Timing
« Reply #8 on: March 06, 2015, 08:12:23 PM »
+1 on timing light. They can be found so cheap at swap meets
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Offline chewbacca5000

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Re: 74 CB750K Timing
« Reply #9 on: March 06, 2015, 08:15:58 PM »
Carb sync always last.
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Offline Bodi

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Re: 74 CB750K Timing
« Reply #10 on: March 07, 2015, 08:53:03 AM »
If the points gaps (measured at full open) are in spec and roughly equal on the two sets, that's what Honda designed it as. The dwell is set by the points gap. You can measure it with a dwell meter and adjust it quite precisely (if you have the time and patience) but getting the gaps right is close enough. It can be quite a chore to get them matched, and some points set brands make it almost impossible (Hondaman has written a few novels in these forums about that).
I went with an electronic ignition decades ago and no longer have to think about this!
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