Topic: Is this the easiest way to adjust ignition timing?

[Dave-and-his-550]

From ignorance comes understanding, I hope...

Anyway, can't you just set the 'F' Mark with the timing mark, and then adjust the point gap just enough to get a spark, then tighten it? Because isn't this the point of adjusting the gap? So there is a spark right at the 'F' mark?

If this would work fine, then whats the point of measuring the point gap to .014 at the 'T' mark?

[Markcb750]

Manuals are on the forum website, they are your friend.

Gap is set at the high point of the cam lobe, timing is set when the points just open.

This opening point starts the collapse of the field in the coil, causing spark when voltage builds to the point that the gap of the plug can be bridged. 

The gap controls the amount of time points are open to allow time for discharge to occur, and for the coils to recharge during the closed part of the cycle. 

[Dave-and-his-550]

Thanks Mark, I do have a Clymers, and I do have the print outs from the CB500-550 shop manuals. I guess what I don't understand is this: what do they mean by the 'cam lobe' and the 'slipper' because the shop manual references both of these. And if I don't know what they are, then I don't know where the "highest position" is to check the gap.

In figure 13 it shows a 1.4 highlighted through the breaker plate hole, so I assume the "highest position" is meant to be the 1.4 T mark, but I don't know.

Is the "slipper" the arm that has one of the points in it, that moves up and down when the crank is turned?

[Spanner 1]

Well, the T mark really is only relevant when you need to find the exact top of the pistons travel in the bore
( cylinder )... the F mark is the important mark for timing the bike and the 14 thou. is critical too. The 14 thou. point gap needs to be set as Mark750 says on the high point of the cam.... not easily seen btw, but there is a tiny scribe mark on the end face of the cam ( visible above the 10mm nut that holds the cam/ advancer on ), that's where you set your 14 thou. for correct dwell..... Dwell is v. important as it is the amount of 'time' the points stay closed allowing the 'charge' to build-up in the coil to max. out the spark when the points open........ when I had a Francis Barnet 150  ( might have to google that )when I was 13 ,
I thought the spark happened when the points closed.... flames out the carb were cool

[Markcb750]

Thanks Mark, I do have a Clymers, and I do have the print outs from the CB500-550 shop manuals. I guess what I don't understand is this: what do they mean by the 'cam lobe' and the 'slipper' because the shop manual references both of these. And if I don't know what they are, then I don't know where the "highest position" is to check the gap.

In figure 13 it shows a 1.4 highlighted through the breaker plate hole, so I assume the "highest position" is meant to be the 1.4 T mark, but I don't know.

Is the "slipper" the arm that has one of the points in it, that moves up and down when the crank is turned?

You are correct about the slipper, it is the phenolic tip that rides on the cam.

the 1-4 is the LH set of points as you look at the cam plate. 

I never can find the scribe mark on my cam so I find the high point by putting the slider in contact with the cam, then slowly rotating it until the points open. Then moving it very slowly till I am confident I have found the high spot, small moves.

repeat this for the 2/3 points.

then set the timing with a test light or meter, 1/4 first. 
I turn on the ignition and look for about 11.5 volts across the points. When the points just open, this drops to zero volts, twist the primary plate so that this occurs at the F mark. 

Attach across the 2/3 points and move the secondary plate to reach the same condition.

You can double check the gap with a dwell meter, some here swear by them, i do not find them necessary to have the bike run well.

I do double check the timing with a light as it allows me to see the mechanical advance work as the throttle is advanced, reaching maximum advance ar about 2500 RPM.

[Dave-and-his-550]

Thank you both. Very informative! I am going to print out what you both wrote and go toy with my timing and proper gap.

It is weird, I couldn't start my bike the other night, and tonight I notice I was getting no spark, so I checked the points plate. I definitely had a problem with it, because when I set it on the 'F' 1.4 mark, I was getting a spark jump on the 2.3 point and vice versa...But now I got that part corrected, and I will now work on proper gap.

I'll hunt for that scribe mark, but why didn't they mention it in the shop manual  It seems like it would have definitely helped to find the high point lol...

[Spanner 1]

Agreed!, it's 1/2 way across the ' hump' on the cam and I only saw it when I had the whole thing apart, but it's definately there, at least on my K1 750.... the scribe mark.

[Dave-and-his-550]

Well I couldn't find any scribe mark on anything! You say its on the cam? Or on the breaker plate some where?

Anyway, I did get the bike started and it seems to idle fine. All pipes heating up good. I think I'll go take it for a ride now. I must not understand how to do this entirely, because after I set the gap at .014 at what I thought was the highest point, my test lamp did not light up at the 'F' mark because of a gap in the points, so I just unscrewed the small plate for 1.4 and moved it so the points would contact, then backed it off just a hair so it would then spark. I then tightened it up. I did this for both 1.4 and 2.3 and it now idles.

But, the gap at the "highest point" may be off now I suppose.

[Spanner 1]

Correct!!.... first you set the gap and then you set the timing @ the F mark... setting the gap @ 14 thou. does not then result in the bike firing at the F mark... it's two seperate functions to set the timing   you have done it correctly

[Cuts Crooked]

I think I'll go take it for a ride now.

So........how'd the ride go?

[Dave-and-his-550]

So........how'd the ride go?

Ahh yes! It went well. I rode it for about 10 miles only though. I'm going to check the timing again today, and the gap, see if anything altered. Soon I know I MUST get a strobe light on there AND rework then sync the carbs, I'm dealing with a "Wandering Idle" I have yet to read through that other thread on this topic. I'm sure my answer is in there!

Edit: If anybody wants to tackle my problem: Basically I'll set the idle at 1100rpm, then after riding the bike around for a couple miles or so, and I come to a stop and put it in neutral, the idle goes up to around 2k rpm. If I knock my fist on the carbs, it changes a bit, but not back to 1100. So, I'm sure the idle jets are sticking or something.

[TwoTired]

The point gap determines the charge level or energy storage level of the coils.  The rotation of the points plate determines where the coil fires in relation to the crank position.

When you change the gap to meet the timing requirements, you cheat the coil's optimum charge strength and ability to fire plugs at a given rotational speed.

This is why you set the gap first and then set the fire timing.

[Dave-and-his-550]

The rotation of the points plate determines where the coil fires in relation to the crank position.

Thanks Lloyd, one question though: If I adjusted the whole points plate base at some point, how do I know or figure out how to get it back in position so the coils fire at the proper crank (piston) position? So long as the test lamp comes on at the 'F' marks, are the points correctly firing with the crank?

[TwoTired]

The test light must change state as the F mark passes the reference groove.
After setting the gap, you rotate the points mounting plate until the above occurs.

[Dave-and-his-550]

By "change state" do you mean it should come on JUST after the F mark passes the reference groove, or off?

[Bodi]

Depends. The coils are powered when the points are closed and not powered when the points are open. A test light across the points will light when they are open. A test light across the coil will light when they are closed. It's easiest to attach a test light across the points so usually it goes on when the points are open.
Be wary of the points moving contact and any wiring attached to it. If you're touching it and ground you get a good jolt of voltage when the points open - not deadly but it wakes you up.

[TwoTired]

Rotate the crank in the same direction as the engine runs.
The static timing bulb should come on when the F mark aligns.

Change state refers to lamp operation.

Lamp should be dark before the mark and change state to illuminated as the marks align.

This assumes your timing lamp is clipped across the point contacts.

[Dave-and-his-550]

Bodi, yes I became aware of that voltage 

Lloyd, I have the test lamp clipped to the blue wire that connects to the point plate then on the yellow wire when I do the other one.

I went out riding this evening and everything ran fine, I think I'm happy with how it is right now 

Clutch was slipping out of second gear into neutral though, occasionally. Think I'll change the oil, I still have the oil in there after I rebuilt it, and I've ran it for 150 miles, I'm kind of paranoid of build up.