Topic: Setting Static Timing on '74 CB750

[emitch]

Can someone please breakdown how to set static timing for a '74 CB750? I've looked at a few resources and writeups from this site, other sites, and the shop manual, and I can say with 100% confidence that I am thoroughly confused.

I have no idea how to begin, so if someone out there can break this down for me in simple terms, I would greatly appreciate it.

Thanks.

[emitch]

bump

[CoachDoc]

Start by accurately setting the points gap on both sets of points. Do you have a 12V test light? This will give you the best indication of when the points are opening to set the static timing (should be at the F mark for the point set involved).

[emitch]

My gaps are set to spec. I'll be picking up a test light later today.

[emitch]

This is the part where im confused - at what points do i hook up the test light? Also, the light should come on when the timing plate is moved and im on the 1-4 index mark, correct?

[CoachDoc]

This is the part where im confused - at what points do i hook up the test light? Also, the light should come on when the timing plate is moved and im on the 1-4 index mark, correct?

Hopefully a 750 guy will jump in here if I'm wrong for your bike, but generally the points plates are stamped 1,4 and the other 2,3. There will be similar stampings on the rotor as you look into the viewing window. Thus there is an F and a T for 1,4, and similar markings for F and T for 2,3. Clip the light across the 1,4 points and rotate the crank clockwise by turning the center bolt on the timing plate. The light will light when the points just begin to open, which should be at the F mark for 1,4. To adjust you loosen the screws and rotate the entire timing plate until the timing is correct. Repeat the process for 2,3 but the adjustment process is slightly different, involving just moving the 2,3 points sub-assembly> Refer to your owner's manual for this. When done if you have an inductive timing light you can hook it up to the appropriate spark plug lead and do a timing check at idle; you can also check your spark advancer at 3000 RPM by looking for the " mark in the timing window. Hope this helps.

[KingCustomCycles.com]

The light is only used to indicate the exact moment the points open.  The light should have the alligator clip attached to the engine case or fins (ground) the pointed end (probe) should be touching the part of the point assembly that moves with the cam.  Points open, light comes on, F mark in the window.  Do this for 1-4 and 2-3,  start and enjoy.

[emitch]

Clip the light across the 1,4 points and rotate the crank clockwise by turning the center bolt on the timing plate.

Thanks for that writeup. What do you mean by "clip the light across the points"?

[KingCustomCycles.com]

"the pointed end (probe) should be touching the part of the point assembly that moves with the cam"

[caferacer750]

is it really that easy

[bryanj]

Sort of yes, you tend to find that when you rotate the plate to set the timing the gap alters as well and it takes time and fiddling to get both the gap and the timing spot on, but if you spend the time and get it absolutely correct it will run better and next time you need to adjust the contact gap (as long as you dont change th econtacts) you can hook up the light and with the timing marks lined up adjust the gap till the bulb lights

[Sdsbassist]

Once the timing is done, do you set the points again?

[evanphi]

Points first, then timing.

That's how the book says to do it. Never hurts to check, though. Just in case.

[goldarrow]

Once the timing is done, do you set the points again?

No

[iron_worker]

Once the timing is done, do you set the points again?

No

Personally, once the timing is set I go back and check the gap to make sure it is still within spec. If you're unable to get the timing set as well as the gap within spec then it means either you are running crappy non-OEM parts (happened to me and many others!) or your points are worn beyond their useful life. One other thing that can happen is that the points plate itself is a slightly loose fit between it's locating "posts" and can shift side to side which makes one gap too tight and one gap too loose (which also affects timing).

IW