Topic: Issues w/ power to points & spark to #2&3 (only running on 1&4)

[bmcdonou]

Hi all. New owner of 73' CB500 with a 75' 550 engine, swapped in by original owner, whom I purchased from. I have discovered that I am only running on cyl 1&4 (so spark) and trying to troubleshoot. Appreciate any help that can be afforded, or resources to point me towards. I've spent a few hours now at the bike, reading manual, on youtube, and reading forum threads. Good info out there but unable to identify my issue.

For context, tho I think it is unrelated. I was doing some maintenance being the new owner, specifically adjust cam chain tension, when I first noticed the issue. Prior to the adjustment, the bike would fire right up and run fine (or so I thought). After the adjustment, it was unable to run for more than a few seconds. At a loss I decided I must have done something wrong in tensioning so I did the process over again and tried to start. Same issue, but then I noticed that only cyl 1 exhaust was hot. I pulled #4 and got spark. Put back in and it started (idk). However, only 1&4 are hot, 2&3 remain cold. I drove it around the parking lot just to see if I would feel different from before, and tbh, at least in first gear, feels about the same. Therefore, it is possible that I've been riding around (city only, no expressway) on 1&4 only (embarrassing as it is to admit that). I call that out because I am not sure if the process of the cam chain tension caused this - tho doesn't seem related.

I initially thought I may have knocked a connection loose at the points so that is where I started. I notice that I only get a current on 1&4 (green wire) and not 2&3 (yellow wire) using a bulb tester. I've rotated cam to the 2&3 fire point and nothing, I forced the points open and nothing. I then pulled wire #3 and tested with a new plug on case and no spark. I went to the coil and pulled the yellow wire connector and it has power.

Here is where I need help:
1 - For me, it is important to have a mental model of how the system works. How does the current get from the battery to the plugs. I am assuming I have a break in the system somewhere and knowing the chain of events will help me mentally break this problem down. I've read the wiring digram which helps, but in itself can be confusing. Does anyone have a good diagram of just the ignition system or can articulate for me? Specifically, how does the relationship between the coil and the points work? I've tried to draw it out myself but I just get lost.
2 - Per the symptoms describe, is there anything else I should be testing to confirm / rule out potential causes (and advice on how to test it)? I am not a spray and pray type person (i.e. just replace everything and hope it works). I'd rather know and solve the problem as it will eat at me not knowing and ultimately want to learn for future. Let me know if that is a newbie way of thinking.
3 - Affirm my line of thinking; based on info I've seen on other posts with people having total/intermediate spark loss, I don't think it is an issue w/ fuse, ignition, or switch as I would assume that would likely impact all wires and not just 2&3. I also assume it is not the condenser as it isn't an issue of spark jumping but none at all. I am thinking it has to be between the coil and the points given 1&4 seem fine (other than the initial temporary issue with #4 which may have just been a loose plug wire).

What I have done:
- Tested spark of #3, no spark (1&4 have spark and run)
- Tested the current at the 2&3 point, forcing open w/ light between the yellow wire at connection and ground, no current (tested same on 1&4 and current as expected)
 - Tested current at 2&3 coil with bulb between yellow wire coming out of coil and ground, current

[bryanj]

Check the connections in the rubber boot by the rear brake pedal, also that you have twisted the connections at the points so they ground all the time.
You may also have knocked the points and there is now no gap.

1 why did you adjust only the cam chain and not do a full service

2 how did you adjust the cam chain

[bmcdonou]

I was just thinking that. I went through the wiring diagram again and made note of all the connections. I assume if power coming out of coil but not getting to point, then must be a break there. I also ordered a multimeter to test the resistance of the coils, and went ahead and ordered two coils just in case. Can return if not the issue, or keep as spair.

Why not full service? - I am in the middle of working through things. I live in highrise that clearly states you cannot work on vehicles in garage. So i want til the evening and then sneak down. I rebuilt front brake system as they were sticking, first. Then cam chain as I felt like I could hear some noise and suspected that might be it. The nut also had crud on it and so suspected it hadn't been adjusted for while. For what's it with, the noise has stopped. I have timing, oil change, and valve clearance on the list. Then this winter I hope to move to a diy garage and do top end and other systems. Also important to note that prior owner had already upgraded at least the charger rectifier. May have done other ignition things....idk.

How I did cam chain? - wrench on point to move to TF14. Removed caps on cyl 1. Initially tight. So 360 then rechecked, they had wiggle. Moved to 15 past tdc (spring just passed mark). Loosen note. Spring bolt with flathead. Tighten nut making sure the bolt did not move (cold not hold with flathead so watched with flashlight and did slowly). Put caps back on.

I did more research today and now realize there are two currents in the ignition system. Primary runs through points and when the point ground is broken allows secondary to go from coils into wires and plugs. So the system is starting to make a little more sense to me.

[robvangulik]

Did you take the tank off to do the camchain adjustment? If yes, maybe you just knocked off a wire from the coils....

[RAFster122s]

It is possible you grounded the points on 2-3 and this is why it is not working. Check carefully the installation of the points and the insulating washer on points 2-3.
You are adjusting the valves so they have proper clearance with feeler gauges right?

[bmcdonou]

I will check, but even when I jump the wire connection to the plate with the test bulb, and force the point open, I dont get a light. Perhaps I am missing something in your suggestion tho?

Re the tank - I did with tank on but will double check all connections as a starting point.

Yes, feeler gauge is ordered and on way. Will use for valves and points clearance once it arrives.

[bmcdonou]

Thanks BryanJ. You were right and I should have gone w/ my first intuition - I knocked something on the point plate when progressing the cam as I was tensioning the chain. I must have look at it 5 times and didn't see it, but after following the ignition wire testing all the connections, I took one last close look. Because I was crouching down looking straight at the plate, I did not notice that the connection for the 2&3 condenser on the right had rotated and was touching the plate. Straightened that out and it started working as expected. A lesson to look very very closely at the details and really inspecting. I also found a few places where the wire holders had worn through and bare wire exposed, so I fixed those.

Unfortunately, upon firing it up, I noticed #2 was still dead. I noticed in all the inspections that there was electrical tape where the wire meets the cap. I assumed it was because the prior owner forgot to put the boot on, but too a look, and it was acting as insulation for bare wire  . I trimmed it and reconnected the cap, but now just too short to make the plug. Unfortunately, the wires and coils are one unit, so have to replace entire thing.

Couple questions:
1 - is it bad to ride the bike w/ one dead cylinder; will it do damage? I have a few errands to run and this is my only mode of individual transportation. Just city driving; few miles.
2 - In long term, as I look to do more wholesale maintenance and repairs, do people recommend moving to an electronic ignition is the current system is working? Any cons to swapping out?

[scottly]

I initially thought I may have knocked a connection loose at the points so that is where I started. I notice that I only get a current on 1&4 (green wire) and not 2&3 (yellow wire) using a bulb tester. I've rotated cam to the 2&3 fire point and nothing, I forced the points open and nothing. I then pulled wire #3 and tested with a new plug on case and no spark. I went to the coil and pulled the yellow wire connector and it has power.

Power goes into the coils on the black/white wires, and is present on the yellow and blue wires when the associated point set is open, and zero volts when the points are closed, grounding that end of the coil primary. If you have power on the yellow wire only when it is disconnected, the wire , or points are grounded. Check where the yellow wire is attached to the points, as this is a common area for mistakes; often, the terminal is either shorting against the points base, or assembled with the insulators positioned incorrectly.   

[bryanj]

1 and this has been said many times DO NOT USE THE BIG NUT BY POINTS TO TURN THE ENGINE unless all plugs are removed, you will damage the advancer unit.

2 yes its bad to run with a cylinder out as the unburnt fuel will wash the oil from the bote

3 you can get in line connectors for ht lead lead , these are not a GOOD repair but should keep you going till new coil arrives(hope you ordered the correct 5 ohm coils as 3 is not good)

[Deltarider]

Before suspecting a coil - which seems to be everybody's hobby here - check the plugcaps. It's the CB500/550's weak spot. Please report when your multimeter has arrived, so we can give some directions. It should be a routine CB500/550 check, to see if there's any accidental arcing - often intermittent - between the plugcap and/or HT lead and the head. This is best seen in the dark. Also realise the sparkplug of the cyl. that didn't fire, may have gone bad.

[bryanj]

Delta the op already reported the ht insulation is burnt by plug cap and too short after trimming.

By the way if using a "joiner" as i suggested it is better to fit it closer to the coil and add a new piece of standard ht lead wrapping the joiner well in good quality tape to minimise shorting

[bmcdonou]

Check where the yellow wire is attached to the points, as this is a common area for mistakes; often, the terminal is either shorting against the points base, or assembled with the insulators positioned incorrectly.   

Yep. This was exactly the issue. And because I didn't get my face right in there, I missed that one corner of the condenser connector was touching the plate the first 4 times I looked at it. I also then discovered that #2 wire had melted and was 'repaired' by prior owner, but was not working so now awaiting parts to repair. So now 1,3&4 all fire just fine.

1 and this has been said many times DO NOT USE THE BIG NUT BY POINTS TO TURN THE ENGINE unless all plugs are removed, you will damage the advancer unit.
2 yes its bad to run with a cylinder out as the unburnt fuel will wash the oil from the bote
3 you can get in line connectors for ht lead lead , these are not a GOOD repair but should keep you going till new coil arrives(hope you ordered the correct 5 ohm coils as 3 is not good)

1 - Interesting about not using the big nut. Initially I tried using the kick start as that is what the manual said to do, but admittedly was difficult. So I opted for the big nut as that is what I had seen others do on youtube. I did notice points where it was more difficult to turn the motor (assume compression). I may then check the advancing component to make sure I didn't do any damage when I do the timing before riding again.

2 - Good call. I will just avoid riding then and perhaps get out the old-school pedal bike for my errands.

3 - I purchased the OEM replica coil kit along w/ caps from 4into1, says 4.6 ohms. I also got a 'tune up kit' that comes w/ new new points. I paid for 3-day delivery so I will just wait vs using a joiner.

I live in Chicago, so short season, and with being my first (street) bike, excited to ride. I plan is to keep working my way through items while riding; focusing on immediate safety and reliability (via late night repairs) and plan to do longer-term performance and reliability things this winter in some sort of DIY garage.

Given that:
 - I will likely just replace the 1 (or maybe both) coils, given they look to be original as I read that even if working can become intermittent or weak (plus already ordered and only $70 w/ caps).
 - I will also likely then do the timing (checking the advance plate) but hold off on the points that come w/ the tune-up kit until winter given they are working (or swap to electronic ignition after I do more reading and research).
 - Valve clearance, as noted before
 - Also on list is oil change; prior owner said he did it at start of spring, but will do again just to be sure and in case the is gas in the oil. Will have to find a way to do in my garage setup or ride to a friends house.
 - Lastly is to find a center-stand so that working on items in highrise garage is easier (and possible to do like removing wheels / suspension).
 - Otherwise, tires newer and good. Already did front brakes and cam chain. Front suspension feels soft, so may get into that once I have a center stand. Chain could use replacing but will do that in winter along w/ sprockets. Lights and everything work fine and I mostly ride during day so not sure how concerned I am about LEDs.
 - Lastly, I did pull all the plugs and 1,2,3 were all black indicating rich mixture. 4 was totally fine but that could have been replaced recently by the prior owner. I went ahead and replaced them and will wait to see after the oil change if it is still running rich before getting into carbs. If I have been riding on 3 cly then I assume gas in the oil could be creating a rich environment.

Did I miss anything? Thanks All!

[bryanj]

When changing oil also change filter, in the casing you put a spring and a thin washer onto the oil filter bolt before the filter, washer is frequently missing as it sticks to the filter and gets thrown away.
Points gap should be 0.35mm or 14 thou do your best to get a set of feelers where you dont have to put two together to get the correct size. Use a bulb from points spring to ground or a multi meter to set toming at the "F" mark for both pairs----yes its a pain to get both gap and timing correct but it is importent to get both correct.
You do not need expensive synthetic or "bike special" oils, a decent quality 10w40 or 15w40 idealy for old diesel engines is fine.
These bikes always tend to run a bit rich its their nature.

Anything else ask

[david 750f]

You stated that the #2 wire is too short. You can swap the 2 and 3 leads to the plugs if they can reach.

[bmcdonou]

When changing oil also change filter, in the casing you put a spring and a thin washer onto the oil filter bolt before the filter, washer is frequently missing as it sticks to the filter and gets thrown away.
Points gap should be 0.35mm or 14 thou do your best to get a set of feelers where you dont have to put two together to get the correct size. Use a bulb from points spring to ground or a multi meter to set toming at the "F" mark for both pairs----yes its a pain to get both gap and timing correct but it is importent to get both correct.
You do not need expensive synthetic or "bike special" oils, a decent quality 10w40 or 15w40 idealy for old diesel engines is fine.
These bikes always tend to run a bit rich its their nature.

Anything else ask

Thanks so much, again, BryanJ. Good advice on the oil change. I had to search hard for basic, non synthetic oil living in Chicago (nobody has old cars here?). I heard synthetic is bad for clutches as it slips. I ended up making a run when visiting my family in the middle of farmland, USA.

I did sneak a peak at the timing when I was dealing with the points issue. I used the light tester to know exactly when the points on 1&4 broke....and it looked to be a good bit forward of the F mark. Is that the mark I follow or is it when the furthest apart. But I moved on given the issue at hand was solving for cyl 3&4. Which is why this is on the list before I drive it too much more. Tho annoying, seems easy enough to solve for w/ some time and patience.

You stated that the #2 wire is too short. You can swap the 2 and 3 leads to the plugs if they can reach.

I thought briefly about this. However, the coil for 2&3 is mounted on the left side, closer to #2. I did check quickly to see if it would reach #1 (to switch the coil to cyl orientation), but it is short. I suspected it would be too short when I make the cut, but no other option, and also believe that this was not the first time it was trimmed (from prior owner) as it really had no play to begin with. I didn't think to check if it would be different if switched to the other side of the frame, but assume 1&2 and symmetrical to 3&4?

[bryanj]

Download the proper honda manual and it will explain the timing marks better but it is the line by the F that has to line up with the casing mark as the bulb comes on

[RAFster122s]

There is a mod you can do dissecting the coil cutting them back to solder in new wires to the posts the existing wires are attached to... Then you replace the plastic removed with epoxy putty and silicone sealer


But that said, a pair of new coils from Parts N More for $80 that come with new wires and you just trim them to fit with room for future trims and put new set of 5k NGK plug Cap's on. Part number 17-6823.

[bmcdonou]

Download the proper honda manual and it will explain the timing marks better but it is the line by the F that has to line up with the casing mark as the bulb comes on

I actually have the original manual that came w/ the bike. I did the timing using the test light and was ahead of the F marks a bit. I set them both back to spec. I had read that putting ahead of the mark a bit is a common performance mod, which perhaps the prior owner did on purpose (he seemed to have a lot of racing bikes in garage), but I just put back to spec. I also did the spacing which they were both between the 0.3mm and 0.4mm, so no need to adjust.

There is a mod you can do dissecting the coil cutting them back to solder in new wires to the posts the existing wires are attached to... Then you replace the plastic removed with epoxy putty and silicone sealer. But that said, a pair of new coils from Parts N More for $80 that come with new wires and you just trim them to fit with room for future trims and put new set of 5k NGK plug Cap's on. Part number 17-6823.

Thanks for the suggestion. While I was waiting for the coils, I did more research on the options of splicing in new wires. For anyone who finds this thread looking for info, I found four options:
1 - What you mentioned, about dissecting the coil
2 - Similar, but splicing and soldering in a wire a few inches exiting the coil
3 - A wire connector made for this, which can be purchased on a few sites (4into1, common-motor)
4 - A filed nail inserted into the wire few inches exiting the coil, then taped and shrink-wrapped (seems suspect)

[Maraakate]

4 - A filed nail inserted into the wire few inches exiting the coil, then taped and shrink-wrapped (seems suspect)

This will work in an emergency.  Only do something like this if you are stranded.  It could come loose or corrode at some point.  When you can get somewhere to get a proper splice then do so.

[bmcdonou]

I finally got the coils and put them on. bolt towards the front was a night mare to get off and nearly stripped it completely but finally the impact driver got enough grip to get it loose after taking the brackets off and removing the setup to get the impact driver a straight shot. Sure enough the replacement coils did not come with a new bolt so I made sure not to over tighten and used locktight (will have to replace eventually).

I only replaced the 2&3 coil and kept enough play in wires in case I ever need to trim in future and routed them in a way not to touch the pipes and melt. Fired up and 1,2,3 were hot, 4 warm. I changed the plug (which didn't look terrible but was a little black) and it seemed to fix the issue (all hot after a min of running).

A couple things I noticed:
1 - When I ran it the first time, I had the plate cover off (bc I did the spacing) and made note to look at it to see if there was any arcing, which there wasn't. But then after replacing the #4 plug, when running again I noticed more arcing. It probably does it every 1 sec or so, and more on the #1&4 point. I read that it is okay to arc occasionally, but not sure how often is more than okay. It was idling at around 1500 RPM, so that 25 rotations per second. Is 1 out of 25 to 50 stokes bad (assuming my math is right) - should I change out the condenser?
2 - Perhaps in my head, but I now can 'hear' the rotation at the points, which I never noticed before. I read in the book that I am supposed to oil the cotton-like material that rubs against the lobe. Is the noise expected or indicative of an issue / need for oil? What oil do I put on there / or what could I use commonly available (book does not mention and bc I am in a high-rise, I don't have a garage full of oil on standby and keeping things to use once is a pain - I have been buying what I need as I need it)? It isn't loud, but you can hear it spin at idle.

[Maraakate]

For the lube get Standard SL-2 Lubricam from Amazon.  You put this on the shaft.  Don't need a whole lot. I just put it on my finger and rub it on the shaft then use the kickstarter with my finger still on the shaft to help spread it and wipe off any excess.

To lube the felt piece I just get some 3-in-1 oil (the one that is more like SAE20 or whatever it is) and put a drop or two on it if the felt is dry and then rub some of the Lubricam on it.

Can't say for sure on the arcing, but seeing some arcing in the dark is normal.

1500 RPM is too high.  Is this via the onboard tach or a portable tach?  Onboard is usually inaccurate.  Idle needs to be around 1100-1200 RPM.  Adjust it to that, take it for a good 10 minute ride, then do a final adjustment on it and leave it.