Question about Timing

[LOUD MOUSE]

I offered my adjustment many years back and have yet to have one complaint but there are many folks riding their bikes today who had no idea how to tune the points and are riding now.
The tools used are common and if they do spend any money it's to get a bulb and alligator clips.
Not everyone has a timing light today as the days of timing your car is over.
BTW I've never said not to use a timing light but if ya don't have one odds are in my favor that if you follow my adjustment you will be OK.
Also in the 60's I never saw the mechanic setting my points use a timing light although the CL72 manual does show using it to check the forward advance.
Add your adjustments to the FAQ as you are determined to have me change mine and I'm OK with the success my adjustment has had over these many years. ............lm

Thank you Ed, but it's your followers relying on your expertise to guide them, by using your timing recipe that really need the luck! Your timing process is suitable for locked-up advancers and for operating on the main stand while in your garage. Not all advancers have the same amount of curve. So if ya ride the bike above 3500 rpm without checking the total with a TIMING LIGHT as Honda engineers designed....then ya must like playing with fire and enjoy seizing pistons.

Tim

Good luck to you Tim. ..........lm

I guess you will do what ever you like with your springs, but if there to stretched or loose the timing will be erratic at idle. Although that's going to require the timing light to witness.

Good luck,
Tim

I guess I'll need to stop discarding and replacing the stretched ones I find.
Good deal. ........lm

The centrifuglal advance springs only control how fast the advance curve comes in.
It does not control how much advance you will end up with.
Were and when the advance weights stop is what determines the amount of advance.
This is why you should always use a timing light.
The spring condition has nothing to do with how much total advance you will end up with.

akpasta, Your OK as long as you don't allow the total to go passed the second mark that is 48 deg. BTDC.

Tim

One of the things I do is check for excess slack with the points cam by moving to the right with my fingers.
If there is very little/no slack then I do my adjustments.
A couple of years back I did check a couple of engines after I set them and the timing was at the first mark and dead on the "F" marks.
This is controlled mostly by the condition of the springs.
Do Not have the timing Past the marks.
With an optimum engine you set the timing between the 2 marks. ..............lm

You both have good points, but unfortunately they're kind of contrary. Loud Mouse, have you ever had over-advance problems when you just set the points static, and not used a strobe? How far past the two marks can you go before you blow an engine? Is 'at the second line' too far?

Trying to find some consensus here.

[akpasta]

I traced some of my timing inconsistencies back to a divot in my right-side points, which made the gap inconsistent between each set. Needed more cleaning. So I sanded them down even more with 400-grit until they closed perfectly. BTW they're only 2000 miles old.

One thing I've noticed about ignition points in general, even on other bikes, is there's always some, like, grey-ish, white coloring on the points, even when you sand them down so they look perfectly smooth and mate cleanly. Are you supposed to sand ALL of that off, so it just looks like smooth metal? I've also read that points have some kind of coating on them, so does this mean you can only take off so much material before they're shot? How do you know how much is too much? I've tried looking this up online, but can't find a definitive answer.

Reason I ask, is both cylinders aren't totally synced up at idle, although they seem synced at advance. Both points of course are opening right at 'F' so my guess is it could be mating surfaces or something changing the gap. I dunno really. Is some amount of inconsistency inevitable with points ignitions?

[Tim Miller]

akpasta,

I have rarely seen the timing perfectly at "F" at idle and perfect at full advance on both cyl.
This is why I believe Ed's way is flawed. You have to choose whats more important to your engines well being.....is it at idle? then do Eds way..... or for me it's at full advance.
I'm Ok with it a little off the "F" mark plus 5 or so degrees and minus 2 deg. or if any less the throttle will be lazy. I normally always rebuild my advancers stops upon rebuild for best results.

Tim

I traced some of my timing inconsistencies back to a divot in my right-side points, which made the gap inconsistent between each set. Needed more cleaning. So I sanded them down even more with 400-grit until they closed perfectly. BTW they're only 2000 miles old.

One thing I've noticed about ignition points in general, even on other bikes, is there's always some, like, grey-ish, white coloring on the points, even when you sand them down so they look perfectly smooth and mate cleanly. Are you supposed to sand ALL of that off, so it just looks like smooth metal? I've also read that points have some kind of coating on them, so does this mean you can only take off so much material before they're shot? How do you know how much is too much? I've tried looking this up online, but can't find a definitive answer.

Reason I ask, is both cylinders aren't totally synced up at idle, although they seem synced at advance. Both points of course are opening right at 'F' so my guess is it could be mating surfaces or something changing the gap. I dunno really. Is some amount of inconsistency inevitable with points ignitions?

[teazer]

I'm not about to take sides here, but you are both right.

To get the timing perfect at idle and at full advance, the range of advance has to be spot on and not all are that way. If I wanted to see how far out, or how close the timing was at both ends of the timing spectrum, I'd use a timing light. That unfortunately doesn't tell me how well my advancer matches the specified advance curve, so in reality it may all be a moot point.

LM is also correct that most CB72/77 machines are not overly sensitive to timing and a few degrees too much or too little advance makes very little difference in the real world. Our race motors with points were set at 45 degrees as a rule and sometimes when I checked, they were only 40 degrees and sometimes they had opened up to 52-55degrees and the things still ran hard and no issues of seizure or overheating - but that was with methanol.

I have no issues with either technique depending on the OP's level of skill and access to tools.

BTW a timing light is not close to accurate enough for my 2 stroke race bikes. Those I try to get to +/- .02mm of where I want them timed and a light just isn't anywhere near accurate enough for that.

[CliffC]

To all concerned I have two Pop Yoshimura bikes a 250 and 305 that I raced in Japan in the early 60's and Pop static adjusted the points with a light bulb. The flyweights were welded to full advance and as best I remember the only failures we had were a couple of broken valve springs. Granted these bikes were only raced and not run on the street and they were bump started. Its been quite a while since I ran my bikes, 1968 if I remember right, and both bikes are disassembled in my garage right now. When I get the time and the ambition and I live long enough I plan on going through both of them, put the 250 back to road race trim and completely restore the 305 to stock looking. Cliff

[akpasta]

Thanks for so much advice everybody.

I'm kind of stumped still. I've been playing with the timing for a week now, almost every day. I set each set of points static to open exactly at F. They have the same point gap when I go back to measure as well. When I check with a strobe light to confirm, the right side idles a little clockwise (advanced) of F and advances to the second line, and when I bring it up to +5000rpms it goes past the second line which is no good. The left side idles almost right at F and advances to the second line.

I know my advance has been rebuilt by Davo before I bought the bike, with new advancer springs, so I don't think it's a problem there after only 2k miles. Unless they have a margin of error no matter what and I just need to deal with it.

I'd like to mention that although I've cleaned them best I could, one of the surfaces of my right-side points has a little crater in the center. I've cleaned them best I can and they touch cleanly, but I'm starting to wonder if a points issue is causing the inconsistency. How often do they need to be replaced? 2k miles seems premature. Could my strobe be inaccurate?

Don't mean to beat a dead horse, but this is the first twin-cylinder motorbike I've ever worked on so really I'm learning from scratch.

[teazer]

What I think you are saying is that you set the timing with a bulb and it's spot on on both sides at the F & LF marks and when you fire the bike up, one side is fine and the other side shows up as advanced at idle and at speed.

If one side is correct, it's not weak springs or too much play in the advancer. The A/R mechanism sounds like it's fine on one side, so we can eliminate that. What is happening is that one side appears OK with a bulb but appears to be advanced with a timing light. That means that for some reason the points actually open on that side slightly earlier than you are seeing with the bulb method.

That's unusual but possible I guess. The points may for example be slightly stiff to open so that at hand turned speed they stay in contact for fractionally longer than when the motor is running.

There may also be a problem with the way you are setting the timing and without seeing you do it, it's hard to say.

You appear to have two choices at this point. Leave it as it is and stop worrying, or simply retard that one side very slightly. Do whichever you feel better about.