Interesting CL77 igntion problem

[Snakeoil]

My '67 CL77 has developed a problem that I'm still sorting thru. It's different than any I've run into before.

When cold, it will start and only run on one cylinder. Up until today, that was the right cylinder. Once you let it warm up and take it down the road, it will start to pop and eventually run on both cylinders and run very well. The problem started on the first day of last weekend's Motogiro (of course) although I now suspect that symptoms were showing themselves previously. But they were showing up when the bike was warmed up. Occassionally the idle would drop or the bike would stall at a light or stop and when I restarted it, it would run, but not well and then clear up.

At the giro that first morning, I pulled the left plug and had spark everywhere but at the electrode. Put in a new plug, and it still ran only the right cylinder. That was when I took it for a spin and it popped a few times then started running on both. Giro was run in the rain and bike was trailered to and from in the rain. I suspected a cracked coil and heat was driving out the moisture.

So today I went thru the ignition. Used Ed's method for setting up the points and timing. Actually, all I had to do was check them. Gap on right was fine and both sets were properly timed. So, I pulled the coils, cleaned them, check continuity on all the leads without unscrewing the terminals and and all were good. Same goes for continuity on the plug wires. Did notice sparking on the right set of points. I cleaned both sets with 400 grit and then with a dollar bill to remove the grit and sparking was not as consistent. I checked spark on the right side with the plug up against the block and no spark. Seem strange because that side always ran good. Logged it away and continued. I also did see occasional sparking on the left set. I know sparking is a symtom of a bad condenser. Another thing I noticed at first, was when I put the timing light on the points, it stayed on regardless of the condition of the points. That's when I cleaned them and the problem went away.

Checked continuity on both condensers to ground and both charged up as they should. No dead shorts to ground.

Put everything back together, double checked my connections and tried to start the bike. Now it runs on the left cylinder really well, but nothing on the right. I know the coils were put back where they were because I never took off the green and yellow leads. So condensers are also hooked up as they were before I dug into things.

It was late and dark and I was done for the day. Will go into it again tomorrow and try swapping condenser wires as well as check the resistance on both coils (forgot that today when a neighbor stopped by to watch me and of course, talk to me while I worked).

I'm pretty sure I put the left and right plug caps on the same wires/sides. It could be a bad cap.

What has me puzzled is why did it clear up when it warmed up at the giro and again yesterday when I took the bike to be inspected? I would expect things to go sour with heat. The coils are metal and only the top is bakelite. Plus, it now has changed sides. I know I need to reconfirm, but everything should have gone together identical to how it came apart. So it should not have changed sides.

My suspicions are:
Bad plug cap (not 100% sure I installed them on the same sides)
Bad condenser (and I hooked them up opposite today and did not realize it)
Plug wires need to be trimmed and reterminated and this is just a coincidence that it changed sides.
Bad positive wire to coil. (might have swapped the feed wires on reconnect, but had 12 at both sets of points when times so doubtful). Need to recheck since I timed it before I disconnected it. Might have intermittent connection.

I'd love to hear if anyone else has been down this spooky road before. I'll report back what I find when I get back into it.

regards,
Rob

[Snakeoil]

Well, there was no way I could not dig back into it this morning. Here's what I found.

Right points were not making good contact. I did find a lot grease on the points cam from the PO and my suspicion is this stuff flung out over time and contaminated the points contacts. I had to go back at them again with emery and then cleaned them with acetone and a piece of cardboard. They turned out to be quite dirty. I think the arcing was from poor contact. Same goes for the problem starting on only one cylinder and then clearing up. I think the pounding of the contacts would clean them up enough to run.

I also suspect I might have had a poor connection on one of the bullet connectors to the condensors. They all looked good but you never know.

Guess I need to spring for a new set of points and probably a new condsensor pack or just make my own from what's available at NAPA.

Starts and runs like a champ, now.

What is interesting is I had cleaned the points and was able to check the timing on both sides prior to the problem switching sides yesterday. Careful, logical inspection and testing of each component took me back to the points. I guess the message is don't assume something is good or bad on these old bikes until you give it a close look and get repeatable test results.

I wish this was 1967. It would have been a simple matter of spending 6 bucks for a new set of points and condensor and that would have been it.

regards,
Rob

[brewsky]

I have found points for older bikes at NAPA before, but had to press them to look a little harder than usual.

They pulled out a parts book with pictures in it and I matched the points up by picture instead of application. They had to order them, but it was like next day delivery, and cheap enough.

Don't know if they still have the books available or not, but it hasn't been THAT long ago.

[Snakeoil]

Gee, Brewski, I never thought of looking at NAPA for the points, too. That's a great tip. Thanks.

Might make that a something for my To-Do list tomorrow.

regards,
Rob

[Snakeoil]

With the spring motogiro approaching, I decided to get a head start on prepping the bike. I bought two complete sets of NOS points and put one set in last week. Prior to doing that, I fired up the bike for the first time after the winter sleep and it ran on only one cylinder.

With new points in place, she fired right up and ran great. Took it for a short spin and put her away.

Today, after finishing my chores, decided to fire her up. She fired right up.... on one cylinder, the left. Pulll the plug on the right and zero spark with the engine running on the left cylinder. Kept running it and suddenly it started to spark, weak but spark and it was everywhere but the electrode. So swapped the plug and had okay spark at the electrode. Not great, just okay. Put the plug in and she ran fine on both cylinders.

Decided to work thru the rest of the electrics for the ign to look for hidden issues. Pulled the plug wires out of the coils, checked all the coil connections, bullet connections, etc. I did find a crummy wire end on the left plug wire at the cap. But that was the side that worked well. I trimmed 1/4" of both wires. I also checked resistance and got about 4 ohms on each wire. Check the resistance on the caps and got about 18 ohms if I remember right. What I do remember is both were nearly identical. Check coil resistance and there both nearly same. Maybe it was the coils that read 18 ohms. The point is I did not find anything that appeared to be a glaring problem.

I suppose I could have a broken wire inside the insulation somewhere. I need to take the tank off again and do more thorough check. Need to measure and wiggle. It has to be something from the coils/consensors, points circuit or the HT lead is iffy.

What is surprising is how well the bike runs when both jugs fire. No misses or stumbles, idles well, acts like a well running engine.

In anticipation of ultimately find a bad component. Is there a prefed coil that fits the OEM bracket others have used with success? I believe I read before that the dual condenser packs are no longer available. Is there an aftermarked condenser that is recommended.

Yes, I will do a search here and will also check out my favorite vendors. Just thought I'd ask in case there are quick answers here.

Thanks,
Rob

[jensen]

Hi,

You could check your ground connections (all of them) by measuring the resistance to ground.
Sometimes these connections have a small resistance, or aren't solid and that will cause all kind of mysterious problems. Don't forget to check (and measure) the engine ground. There should be no resistance between the engine and frame / battery negative.

Remember, rust, paint grease cracked wires and air are very good isolators,

The reason you have to check your engine ground is that you say it sparks everywhere except at the spark plug. A spark plug has a certain resistance to ground, this resistance is formed by the copper, resistance wire of the caps and the air gap between the electrodes. As you probably know, a voltage difference will lead to current flow, and the current will find the lowest resistance to freedom, and for some reason at your bike it aren't the electrodes,

Good luck,

Jensen

[brewsky]

Is there an aftermarked condenser that is recommended.

Rob

Rob,

I'm using one from a CB750K on my Dream, and it matches the .21-.27 mfd spec given in the shop manual. Works fine.

Actually, the Honda shop manual specs .1 - .31mfd, and the Clymer says .21 - .27mfd, and neither makes a delineation between CA, CB, or CL models.

You would need 2, one for each set of points.

Also, have you checked coil polarity?