Topic: Ignition Timing Problem '76 CB550k

[Mangino92]

A few months ago I bought a '76 CB550K as a project bike. I have been working on it in my (limited) spare time. I just set the points gap and now I am trying to set the ignition timing. I connected a 12v test light and turned the crankshaft to see if it was already accurate. The light came on about half an inch before the "F" marker. So I aligned it to the correct mark and loosened the points plate screws. From what I understand you're supposed to turn it until the light goes out, correct? My problem is that the light never goes out, no matter the position of the plate. Another thing I noticed is that if you keep turning it past when the light initially comes on, it stays on almost until the markings for cylinders 2&3 come into view (I guess when they are firing?) I just want to get this done and I feel dumb for not being able to figure out such a routine thing.

[dgedinyte]

Sounds like your gap is too wide. Also make sure your point plates are at the widest point of adjustment when you set the gap.

[Mangino92]

Are they fully open at TDC or is there an easy way to tell when they are? Or do you have to eyeball it? And are they only fully open at one specific degree, or is there a range?

[Duanob]

Frankly I think it's easier to use a dynamic timing light. You can check advance as well.

[Mangino92]

Unfortunately I don't have one, nor do I have the extra money to buy one.

[TwoTired]

First you have to set/adjust the max gap opening by rotating the crankshaft and watching for the maximum point gap, not any timing marks.
You also have to make sure that there is no insulative film wax/grease/oxidation on the point contacts.  A quick swipe with a points file should do it. (NO SANDPAPER)

You watch the lamp as you turn the crank past the marks and the light should come on when the marks align.  This is when the points open, firing the coils.

If the light misses the mark you move the 1-4 base plate a bit, and then turn the crank again to watch for the light.  This is a reiterative process, until the base plate alignment results in the correct light when marks are aligned while moving the crank.

Once the 1-4 plate is locked down, you repeat the process for the 2-3 sub plate/points.  Rotate the crank for the timing observation, move the sub plate to change the timing.

A timing light is NOT easier, especially if you consider that the 1-4 plate can move about in its mount bosses when the screws are loosened and the point cam rotating and changing tension on the point springs.  You can chase your tail for hours fiddling with getting both the gaps and timing correct for both point sets.

If you insist on a strobe timing light, you probably should learn to shim the main plate as described in the FAQ.

[Mangino92]

If the light misses the mark you move the 1-4 base plate a bit, and then turn the crank again to watch for the light.  This is a reiterative process, until the base plate alignment results in the correct light when marks are aligned while moving the crank.

I think this is where I was misinformed. Adjusting and testing in multiple increments, which actually makes more sense to me than what I was told. I will try this a little later today. So if the light came on a little too early then I need to rotate the plate clockwise or counter?

[dgedinyte]

To me (and the manual) you need both mthods, and both lights. Use your static light to make the initial setting for 1 and 4 and 2 and 3. Then crank the bike and check it with the strobe light. No matter how acurate you are with that static light, the strobe is the real test of where it's firing during operation. Once firing at the f mark is proven with the strobe, crank up the RPMs to about 2600 and chck with the strobe that it is firing between the advance marks.

[Mangino92]

Well I tried again and I have rotated the plate as far as it will go and it still isn't to the "F" line. It only gets to the actual letter "F". What now?

[goldarrow]

Turn the crank until spring peg line up with the mounting plate screw for 1-4. Set your gap. Do the same for 2-3.   Start up the bike, Use strobe timing light. Rev throttle until the strobe line stop moving and adjust your plate to full advance.

Someone else can probably explain better though

[TwoTired]

Well I tried again and I have rotated the plate as far as it will go and it still isn't to the "F" line. It only gets to the actual letter "F". What now?

Have you set the points gaps correctly?  To what spec?

Have you looked at the ignition FAQ?

[Jimsun]

Did u do any mods to it like a cam swap or top end?

[Mangino92]

I set the gaps with the .014-.016 feeler gauge.
No serious mods to my knowledge. Previous owner said he never got into the engine.

[dgedinyte]

That picture looks like it's firing right(if that's at idle). ramp up the RPMs and check to see if it's advancing correctly. the two marks that can be seen in your pics to the right of the F are the advance marks.At full advance (not sure what the RPMs for full advance are on the 550) the fixed timing mark on the top should line up between those two marks. Above the F on my advancer there is a line. You just have the F. The two marks to the left are something else entirely.

[TwoTired]

That picture looks like it's firing right(if that's at idle).

Hell no!

ramp up the RPMs and check to see if it's advancing correctly. the two marks that can be seen in your pics to the right of the F are the advance marks.At full advance (not sure what the RPMs for full advance are on the 550) the fixed timing mark on the top should line up between those two marks. Above the F on my advancer there is a line. You just have the F. The two marks to the left are something else entirely.

Is this ethanol "fueled" advice?   You can't "ramp up" the RPMs when doing a static time!

 Have you ever looked at the manual (owner's or shop)?


Me thinks that Mangino is going to have to shim the 1-4 base plate, which is too small to fit in the engine bosses tightly.  Explained in the FAQ.

[Mangino92]

Just a random thought. Why couldn't you take a drill and use the side of the bit to lengthen the adjustment slots a little? Would that cause problems?

[TwoTired]

Just a random thought. Why couldn't you take a drill and use the side of the bit to lengthen the adjustment slots a little? Would that cause problems?

It's a hack, but it works.  The side of the drill can wander, though.  And, there is three of them to do in the same arc/same way.  But, if preparing the bike for the apocalypse, whatever works for you. 

What you suggest has been done before.  I've thrown away plates from used bikes, that this was done to.

Can you see the brand stamp on the points?  Diachi has a bad reputation for bad geometry.  Some of the problems you are encountering are fixed by getting TEC brand points.

[dgedinyte]

That picture looks like it's firing right(if that's at idle).

Hell no!

ramp up the RPMs and check to see if it's advancing correctly. the two marks that can be seen in your pics to the right of the F are the advance marks.At full advance (not sure what the RPMs for full advance are on the 550) the fixed timing mark on the top should line up between those two marks. Above the F on my advancer there is a line. You just have the F. The two marks to the left are something else entirely.

Is this ethanol "fueled" advice?   You can't "ramp up" the RPMs when doing a static time!

 Have you ever looked at the manual (owner's or shop)?


Me thinks that Mangino is going to have to shim the 1-4 base plate, which is too small to fit in the engine bosses tightly.  Explained in the FAQ.

So sorry. I just reread that you don't have a timing light. I thought you were posting pics of the strobe flashing with the bike at idle. That being said, I've only done this to 750 and the pic of the advancer you posted is slightly different than mine. But on mine you want the F to line up with the fixed timing mark at the top. In your pic it looked like the F was in fact lined up with that mark. Now Mabee on the 550 it's the line directly behind the F. But on the 750 the T mark behind the F is used for something totally different. Take a look at the pic. The red line at the far left that's the T mark. It's not used for ignition timing.

[Mangino92]

It says TEC on the plate. I suppose I'll try shimming next.

[goldarrow]

Get timing light.  Adjust to full advance mark when rev above 2500 rpm. Let it be wherever it is at idle.  Dave500 can say this better than I do. 

[Jimsun]

I have this problem too. My light goes on between the "F" and "1" mark. So what i did was readjust the plug to .018 and i got it close to the "|F" mark. I think going wider will be bad. I may shim it too if it ends up working for you. I do have the TEC base as well

[Mangino92]

Well mission accomplished. Not sure precisely what did it as I was fiddling for a while. Shimming definitely helped. Also I randomly remembered reading  somewhere to set the 1-4 gap, then time 1-4, then set 2-3 gap then time 2-3. I think that also helped. Unfortunately I didn't get a chance to see how it ran. Thanks to everyone for the help.

[Deltarider]

 

somewhere to set the 1-4 gap, then time 1-4, then set 2-3 gap then time 2-3. I think that also helped.

I remember I also posted this procedure somewhere. Still I would consider this. Suppose PO or dealer(s) have never loosened and moved the plates and have done the timing by simply adjusting the breaker points gap. That's not a strange thought as almost all timing variations come from changed breaker points gaps.
Why not - for a start - forget what is in all the manuals and set the timing by adjusting the breakerpoints gaps. Then after you're satisfied with the timing you can still check if the gap opening is within limits.
Dealers here used to do this and it was quite normal the screws of the plates were never even touched.
Long ago I have set my timing correctly and ever since I just adjust the breaker points gap if adjustment is needed at all (seldom the case).
Much simpler. Only two screws in stead of five.
If you'll find gaps are outside limits however, you'll have to go trough the full routine ofcourse.
I just wondered how many bikes overthere have the plates never been touched since they surface with so few miles on the odometer.
Just a thought and I hope I can save some of you a lot of unnecessarily hassle.

[TwoTired]

The point gaps along with the points cam profile set the dwell or charge time of the coil.  While the coil doesn't always need to be fully charged, the actual dwell time (rather than the crank degrees of rotation) reduces with higher RPMs, as the crank completes a rev in less actual time, which reduce the time the coil has to charge up for the next spark event.

You can fudge on the gaps and still have a bike that runs.  But, you are relying on extra engineered margins of the parts and design to get a good reliable spark in the stock system.  The margins naturally erode with point contact resistance increases and wear, and weak batteries during electric start operation can make the spark less than optimal as well as electrical connection that lose voltage.   Further spark plug electrode errosion, widens the gap and make higher spark voltage a requirement.  (These are also reasons for periodic tune up intervals.) If all the design margins are consumed with shoddy,fudged adjustments and other ailments you are asking for eventual reliability issues.

Also, I don't agree with setting the timing at full advance and ignoring idle timing.  That's a procedure developed by the electronic ign. aftermarket salesmen.  If you can't get both idle timing and full advance timing on your point system, something isn't working right and should be repaired rather than ignored.   Of particular concern, is if the idle timing isn't identical for the two sets of points.  This WILL lead to lower end trans rattle/gear clack at idle as the cylinders fight for crank rotation speed domination.  But then, if you also fudge on idle speed setting by upping it higher, this problem can be masked. too.

[Deltarider]

Personally I have not experienced an 'off timing' other than originated by a changed breakerpoints gap, but that's just me. Looking at it from the other side: if I reset the dwell (if necessary at all) at the values I've put down in my notebook long time ago, my ignition timing is always spot on. So for many years I haven't touched my plates and had to deal with two screws only and not 5 or even 7.
BTW, this has been the routine in many workshops.
If you have disassembled the ignition completely it is mandatory ofcourse to follow the procedure as described in the manual.
I can't help having the feeling there's too much (read: unnecessary) 'adjusting' the plates where simply adjusting the breakerpointsgap would have been sufficient. Just my opinion.