Author Topic: gapping points  (Read 1592 times)

0 Members and 1 Guest are viewing this topic.

keener

  • Guest
gapping points
« on: July 11, 2008, 01:00:27 PM »
when gapping points Ive seen that you can take the gap at the spring post after the 1.4 F if your doing the 1.4 cyl, and ive also seen to take the gap AT the "F" which is correct??

Offline bozo4onion

  • Hot Shot
  • ***
  • Posts: 368
Re: gapping points
« Reply #1 on: July 11, 2008, 01:17:34 PM »
I gap @ the highest lobe peak.

keener

  • Guest
Re: gapping points
« Reply #2 on: July 11, 2008, 01:19:15 PM »
which is?...looking at it is not very accurate.

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,805
Re: gapping points
« Reply #3 on: July 11, 2008, 01:44:00 PM »
when gapping points Ive seen that you can take the gap at the spring post after the 1.4 F if your doing the 1.4 cyl, and ive also seen to take the gap AT the "F" which is correct??

Neither.  What/who told you that?

You find the high point of the points cam by rotating the crank and then set the gap at it widest opening to spec value.

Do you have any manuals?

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline medic09

  • Old Timer
  • ******
  • Posts: 2,666
Re: gapping points
« Reply #4 on: July 11, 2008, 03:20:59 PM »
Keener, if you haven't yet gotten them, buy a Clymer and a Honda shop manual for your bike.  They'll help immeasurably.  Almost as useful as TT here.  ;)
Mordechai

'78 CB750K
'76 Triumph T160 Trident (rebuilding)
'07 aprilia Caponord

Santa Fe, NM

keener

  • Guest
Re: gapping points
« Reply #5 on: July 11, 2008, 03:25:57 PM »
ya I got it, I read a post in another section saying to ref the "F" and not the high point

Offline Dennis

  • Hot Shot
  • ***
  • Posts: 721
Re: gapping points
« Reply #6 on: July 11, 2008, 03:47:26 PM »
Keener,
As mentioned earlier, you set the gap at the high point. Visual observation of this is fine. People have been setting ignition points in this manner for many years.
TT is one of our most knowledgeable members, he WILL NOT steer you wrong. Follow his advice.
Also, as mentioned, get yourself some good service literature.
If you set the point gap at the F mark the bike will most likely not run at all, and if it does run, not very well.

Offline BobbyR

  • Really Old Timer ...
  • *******
  • Posts: 12,367
  • Proud Owner of the Babe Thread & Dirty Old Man
Re: gapping points
« Reply #7 on: July 11, 2008, 05:16:42 PM »
If you are adept at using a feeler gauge finding the widest opening is very simple. As TT said using the eyeball method is very simple and effective. You find what you eye tells you is the widest point. Set your gap using the feeler. If you rotate the the engine and find no point the blade becomes looser, you got it done. If you are using a new feeler gauge, wipe off any rust inhibitor that is on the blade with some solvent before you use it.
Dedicated to Sgt. Howard Bruckner 1950 - 1969. KIA LONG KHANH.

But we were boys, and boys will be boys, and so they will. To us, everything was dangerous, but what of that? Had we not been made to live forever?

keener

  • Guest
Re: gapping points
« Reply #8 on: July 11, 2008, 05:20:22 PM »
I got it now and its running great thanx all... :)

Offline markjenn

  • Enthusiast
  • **
  • Posts: 238
  • CB750K1, CBX, RC30
    • Whizmo and Gizmo
Re: gapping points
« Reply #9 on: July 11, 2008, 05:40:10 PM »
Could be wrong, but I think the points cam has a very wide plateau where it is at peak lift for 90+ degrees (unlike a valve cam which is pointy) so anything on this plateau is fine for gapping.  And points gap is not a super-duper critical measurement anyway, as evidence the wide variance in the spec (0.3mm-0.4mm for a 750).  On many early Hondas they didn't even give you a one-side-only rotating points backing plate, so you had to use point gap variance as a way to set timing on one side independent of the other side.

So eyeballing where point gap is maximum is fine, get the points gap roughly in spec, but be sure to get the timing spot on.

- Mark

Offline TwoTired

  • Really Old Timer ...
  • *******
  • Posts: 21,805
Re: gapping points
« Reply #10 on: July 11, 2008, 07:03:40 PM »
So eyeballing where point gap is maximum is fine, get the points gap roughly in spec, but be sure to get the timing spot on.

Sure, if you just want it to run. 

The point gap is the dwell setting, which is the time available to charge up the coils.  If you make the dwell too short, the coils don't achieve full saturation, and won't create enough voltage to spark the plugs.  The Dwell setting is much more critical at high RPM when charge time is the shortest.  Eyeballing the gap is fine to get the bike moving.  If you want it to work best at or near red line, then pay attention to the point gap specification.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline markjenn

  • Enthusiast
  • **
  • Posts: 238
  • CB750K1, CBX, RC30
    • Whizmo and Gizmo
Re: gapping points
« Reply #11 on: July 12, 2008, 12:30:03 AM »
So eyeballing where point gap is maximum is fine, get the points gap roughly in spec, but be sure to get the timing spot on.

Sure, if you just want it to run. 

The point gap is the dwell setting, which is the time available to charge up the coils.  If you make the dwell too short, the coils don't achieve full saturation, and won't create enough voltage to spark the plugs.  The Dwell setting is much more critical at high RPM when charge time is the shortest.  Eyeballing the gap is fine to get the bike moving.  If you want it to work best at or near red line, then pay attention to the point gap specification.

Cheers,

I agree, the gap should be within spec.  My point was that the gap spec is pretty wide which means that the gap isn't super critical... anywhere in the range is fine.  And when I said you can "eyeball it" I meant that you can eyeball where the gap is widest and you're in the high area of the point cam... as you say, you still need to use a feeler gauge.

- Mark