[Mike from Atlanta]

Hello all. Been lurking for quite a while now but figure it's time to sign up.

About me: I'm an ICU Registered Nurse at a big Atlanta hospital. I bought a 1983 Suzuki GS550 when I was 17 years old and have had about 15 bikes since then. Most of them Japanese and most of the standard street bikes. Last running bike was a KLR650 that I rode for 7 years and about 70k miles including a few big trips. The motor died right before my son was born 3 years ago, and I haven't ridden since (except my Yamaha Zuma 125 commuter scooter).

About the bike: Met a guy about a year and a half ago that was looking to clear out his garage in preparation to move. He heard I like to work on motorized things and made me a deal I couldn't refuse. He'd let me have it for $200 if I could get his 1982 CX500 out of his garage that day. Hadn't been run in 5 years or so. I brought it home, put in a new battery, spark plugs and cleaned out the fuel tank. That's about as far as I got before Covid got crazy in Atlanta and I started working a lot of extra shifts. Just now getting back to resurrecting this old girl.

It will start and run, but intermittently drops the left cylinder. I'm gonna get in the shop tonight and start troubleshooting with the help of all the online resources for the CX500. I'll start another post as I start to dig in to the old girl.

 

[D-Fresh]

Welcome to the forum. You've come to the right place, there are some very knowledgeable folks here.

Cheers

 

[keith in zulu In]

You are one of the heroes in the world. To help all those people fight Covid. I hope is bike gives you a little R&R from work that you truely deserve. Sounds like a good carb cleaning is what you need and the best way to do that is Larry's Carb Book.

 

[Mike from Atlanta]

Hello all. Been lurking for quite a while now but figure it's time to sign up.

About me: I'm an ICU Registered Nurse at a big Atlanta hospital. I bought a 1983 Suzuki GS550 when I was 17 years old and have had about 15 bikes since then. Most of them Japanese and most of the standard street bikes. Last running bike was a KLR650 that I rode for 7 years and about 70k miles including a few big trips. The motor died right before my son was born 3 years ago, and I haven't ridden since (except my Yamaha Zuma 125 commuter scooter).

About the bike: Met a guy about a year and a half ago that was looking to clear out his garage in preparation to move. He heard I like to work on motorized things and made me a deal I couldn't refuse. He'd let me have it for $200 if I could get his 1982 CX500 out of his garage that day. Hadn't been run in 5 years or so. I brought it home, put in a new battery, spark plugs and cleaned out the fuel tank. That's about as far as I got before Covid got crazy in Atlanta and I started working a lot of extra shifts. Just now getting back to resurrecting this old girl.

It will start and run, but intermittently drops the left cylinder. I'm gonna get in the shop tonight and start troubleshooting with the help of all the online resources for the CX500. I'll start another post as I start to dig in to the old girl.
View attachment 210588

You are one of the heroes in the world. To help all those people fight Covid. I hope is bike gives you a little R&R from work that you truely deserve. Sounds like a good carb cleaning is what you need and the best way to do that is Larry's Carb Book.

Thanks

You are one of the heroes in the world. To help all those people fight Covid. I hope is bike gives you a little R&R from work that you truely deserve. Sounds like a good carb cleaning is what you need and the best way to do that is Larry's Carb Book.

Thanks Keith! It's been a helluva couple years at work. It'll be a lot nicer when I can ride this motorbike back and forth to work.

I think it may be an electrical/ignition problem due to the intermittent nature of the failure. Usually it will start up on both cylinders from cold. It'll run fine and take throttle for about 30-60 second before the left cylinder drops out. After it drops, spraying carb spray into the intake does not bring the dead cylinder back to life. Also with the bike running on the right cylinder, and the left plug stuck in the boot and grounded to the engine the left cylinder still has spark. I would think that if the left carb was plugged the cylinder would come to life when I spray carb cleaner in the intake. The fact that the cylinder still has spark but won't run is a bit puzzling. Could be that the spark on that side gets weak once it heats up (bad coil or HT lead). Could be an issue with the ignition timing mechanism. Could be valve lash too tight on that side and it loses compression after it warms up a bit. I'm going to start doing diagnostics within this upcoming week and start another thread once I have more information.

 

[mtreis86]

Check the coils and the stator, there is a pinout chart somewhere in this forum for the stator connections, I am assuming it is CDI ignition

 

[Mike from Atlanta]

Check the coils and the stator, there is a pinout chart somewhere in this forum for the stator connections, I am assuming it is CDI ignition

Mtreis86 I'm walking out to the shop right now to swap the coils from side to side and see if the problem follows the coil. After that I'll start doing the stator and pulse generator tests I've found online. I believe mine has the TI ignition.

 

[mtreis86]

Mtreis86 I'm walking out to the shop right now to swap the coils from side to side and see if the problem follows the coil. After that I'll start doing the stator and pulse generator tests I've found online. I believe mine has the TI ignition.

From my understanding (and I hope someone here will correct me if I am wrong) the TI units rarely have issues. The main difference (in terms of how things break) is the TI system doesn't use separate stator windings for the ignition process, the stator is all for battery charging. Worth checking anyways, but make sure the tests are for the right ignition type.

 

[Mike from Atlanta]

From my understanding (and I hope someone here will correct me if I am wrong) the TI units rarely have issues. The main difference (in terms of how things break) is the TI system doesn't use separate stator windings for the ignition process, the stator is all for battery charging. Worth checking anyways, but make sure the tests are for the right ignition type.

Thanks will do. I've been reading up and trying to understand the ignition systems. Mine does charge just fine. 14.36v at the battery while running.

 

[mtreis86]

Basically there are two voltage levels these systems operate at, the TI system uses 12v at the coil, and the CDI system generates 100v for the coil. The TI system is a lot like a modern car, there is a computer that gets a signal for crank position, and that is used to time a transistor (the T in TI) that releases a pulse (I forget if it pulses positive or negative) to the coil. The CDI on the other hand needs a lot more power, so it has a seconday winding on the stator to generate that power, which then goes into a capacitor (CD is Capacitive Discharge), which gets pulsed into the coil. Higher voltage components are more sensitive to things like vibration and insulation being damaged so the CDI system tends to have more issues.

 

[bahn88]

Welcome.....After spending a day in level3 or level4 PPE....nothin better than taking a bike for a run...after the obligatory shower...

I only work in a small hospital with the occassional Covid/Scovid case.....but my bikers beard had to go.....

 

[Randall-in-Mpls]

I think you're likely to find a failing coil or excessive resistance in a plug cap. The gray ignition modules are pretty robust, but sometimes (infrequently) go bad.

 

[Mike from Atlanta]

Welcome.....After spending a day in level3 or level4 PPE....nothin better than taking a bike for a run...after the obligatory shower...

I only work in a small hospital with the occassional Covid/Scovid case.....but my bikers beard had to go.....

Bahn88 you're right about that... Nothing like some high speed wind in your face to knock off the Covid PPE funk. I work in a big metropolitan hospital and we have been eyeball deep in Covid. Right now the numbers are down but we're all just waiting for the winter Covid/flu combo to kick in. Lucky for me I never could grow a proper beard so I had nothing to lose.

 

[Mike from Atlanta]

I think you're likely to find a failing coil or excessive resistance in a plug cap. The gray ignition modules are pretty robust, but sometimes (infrequently) go bad.

Randall- I swapped the coils last night too see if the problem followed the coil. It did not so I think I can rule out the coils. I've already swapped spark plugs to no effect so I can rule them out. Next I'm going to try swapping the HT lead/plug caps to see the problem follows that. If that doesn't get it I can swap out the gray ignition modules.

I did notice a couple things while messing with it last night. First, my kill switch is finicky. Sometimes I would lose spark on both sides. Wiggling the kill switch rocker just slightly would remedy the issue. I don't think this is related to my dropped cylinder but it's an issue I'll have to address.
Second, while I still have spark on both sides even when the left cylinder isn't firing, I think the left cylinder spark isn't as bright as the right. That could point to increased resistance in the plug cap or wire like you said Randall. I'll have time to mess with it again tonight and post the results.

 

[Sidecar Bob]

If none of that fixes it the next step is to check the pulse generators. If you haven't already done so download the Factory Service Manual (available from the CX Wiki - link in my signature) and do what it says - it explains how better than I can.

Problems with switches can usually be remedied with contact cleaner and often without taking them apart. If you look at the bottoms of your switch assemblies you will see that there are small holes, just the right size to accept the straw from the contact cleaner and located so that it will spray right onto the contacts. Just spray the contact cleaner into the hole and work the switch or button vigorously several times, then turn on the key & try it. You might need to repeat the process several times before it works properly.
Note: You need to have real electrical contact cleaner. WD40 is a fine product and has many uses, but it is not real contact cleaner. It leaves a sticky residue that will attract dust and you will have dirty contacts again before you know it.
If you can't get it working after 3 or 4 tries you will need to take it apart. And don't use brake cleaner or carb cleaner because some of them can melt the plastics used in switches.

BTW: Welcome to the forum and welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and may or may not have had all of the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). It looks like your bike still has the original rubber brake line, which should have been replaced every 2 or 3 fluid changes (= 5 or 6 years) so I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).

 

[Mike from Atlanta]

If none of that fixes it the next step is to check the pulse generators. If you haven't already done so download the Factory Service Manual (available from the CX Wiki - link in my signature) and do what it says - it explains how better than I can.

Problems with switches can usually be remedied with contact cleaner and often without taking them apart. If you look at the bottoms of your switch assemblies you will see that there are small holes, just the right size to accept the straw from the contact cleaner and located so that it will spray right onto the contacts. Just spray the contact cleaner into the hole and work the switch or button vigorously several times, then turn on the key & try it. You might need to repeat the process several times before it works properly.
Note: You need to have real electrical contact cleaner. WD40 is a fine product and has many uses, but it is not real contact cleaner. It leaves a sticky residue that will attract dust and you will have dirty contacts again before you know it.
If you can't get it working after 3 or 4 tries you will need to take it apart. And don't use brake cleaner or carb cleaner because some of them can melt the plastics used in switches.

BTW: Welcome to the forum and welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and may or may not have had all of the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). It looks like your bike still has the original rubber brake line, which should have been replaced every 2 or 3 fluid changes (= 5 or 6 years) so I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).

Sidecar Bob- Thanks for the post that was a lot of useful info in one place! And thanks for pointing out the factory service manual. The Clymer manual came with the bike but it is woefully incomplete (mentions nothing about the newer TI ignition for example). I just downloaded the factory manual and will print it as soon as I can.

1) Question about the pulse generators- If the pulse generators fail, will it still spark at all? Mine still sparks even when the left cylinder doesn't run. It may be a little weaker of a spark than the right side but hard to tell. I wondered if maybe the pulse generator failure might cause weak spark or spark out of time? If my other troubleshooting things don't work I'll definitely do the diagnostic from the manual.

2) Thanks for the tip about the kill switch. I do have some proper electrical cleaner spray and I'm going to go try your suggestion in a few minutes.

3) I certainly intend to go through the whole bike as you recommend including carb service, brake lines, I already rebuilt the caliper and replaced the brake master cylinder, new tires, valve adjustment, etc.etc. I learned the hard way how slick old tires can be several years ago. I was helping a friend work on his 1995 Honda VFR750 with original tires. I took it for a very slow test ride around the block. Back tire broke traction under the slightest of throttle and lean. It's the only time I've ever high-sided a motorcycle. Luckily the damage to me and the bike was minimal.

4) I see from your signature that you're from Ontario. I rode from Atlanta to Western Ontario with a friend about 10 years ago. I was on a KLR650. Went through Thunder Bay and headed north and west through Sioux Lookout. Rode offroad on a section of the Trans-Canada trail. Don't know where you are in Ontario, but the part I rode through was beautiful.

 

[Mike from Atlanta]

Thanks for the welcome and all the good information everyone! I think I'm going to start a new post soon about this specific problem of the cylinder not firing. I'll try to keep reposting updates on a timely basis. Work is a bit hectic these days, plus it's the beginning of deer hunting season here in Georgia which will account for some of my days off in the next couple of weeks.

 

[bahn88]

Enjoy your bike and Stay Safe..

 

[Sidecar Bob]

I think there could be weak sparks if a pulse generator is in the early stages of failure. But check the spark plug cap first.

 

[tomswift]

Didn't see where you examined the plug itself... if plug is fouling, bike may run on choke (tons of fuel to burn) but die when running leaner.

I am in the ATL area, and I have a set of replacement plug caps if needed. I also have spare ignition modules, although as noted these rarely go bad (but I have seen a couple do so)PM me and we can talk

 

[Mike from Atlanta]

Didn't see where you examined the plug itself... if plug is fouling, bike may run on choke (tons of fuel to burn) but die when running leaner.

I am in the ATL area, and I have a set of replacement plug caps if needed. I also have spare ignition modules, although as noted these rarely go bad (but I have seen a couple do so)PM me and we can talk

Tomswift- Thanks! I was out of town for a few days and working 12 hour shifts that and tomorrow so I haven't tinkered with the bike. The plugs are new and I have cleaned them a couple times as I've been working on the troubleshooting. Also checked the plug gap.

Thanks for the offer I'll definitely message you soon. I'm in Decatur. I'd be happy to trailer the bike over to you and try a couple of your spares to see if they help identify the problem. So far I've just been switching components from side to side to see if the problem followed the component and so far no luck. I plan to check compression on both cylinders to see if it could be a valve issue or head gasket even though I suspect the problem is electrical. I had to order an adapter to get my compression tester to fit the 12mm thread. Also plan to check diagnostics on the pulse generators. I'll message you soon!