First GS, Ignition Gremlins!

[Guest]

Quick intro: My name is Mike, first post, new member. I've been lurking this forum for about 6 months now since I picked up my first motorcycle, a 1982 GS450L. I'm one of the oddballs who waited to get a bike license until 25 years old, so i'm a bit of a late bloomer with road-going bikes at least.

I picked up an '82 GS450L from a coworker in March(?). It sat outside for years before I picked it up. I went through the majority of the bike, checking and replacing some things as I went along. I finally got it up and running last weekend. It rode great for two days, though a partially clogged main jet in the left cylinder carb was causing some issues. I was riding it home and I lost cylinder one completely, and shortly after i lost cylinder two. I contributed it to "running out of fuel" since I had only planned to "go around the block". However, once back at the garage and gassed up, the main fuse had blown, and the cylinder 1 ignition coil was completely burnt up, with some cooked (tar-looking) internal juices escaping along with the scent of what I would assume a fire at the HP factory would smell like. A multimeter confirmed it was shot. I tried 3 known-good spare ignition coils with no luck on getting the left cylinder to fire. The right cylinder works no problem, with any of these ignition coils. I've heard that these bikes are notorious for burning out igniters, and sometimes can do so one cylinder at a time. Now, my question is, before my brand new ignition coil comes in the mail, I want to find the source of my problem before plugging it in and cooking a brand new one due to another fault down the line.

Is there a multimeter bench-test procedure for the ignitor? Could a RR cause this issue? I do not have a service manual at my disposal, and scanning the internet for a PDF of any of these procedures has yielded mediocre results.

Thanks a ton for the awesome information this site has provided me over the past 6 months, and helped a bike n00b make some great headway!

[fastbysuzuki]

Is there a multimeter bench-test procedure for the ignitor? Could a RR cause this issue? I do not have a service manual at my disposal, and scanning the internet for a PDF of any of these procedures has yielded mediocre results.

Thanks a ton for the awesome information this site has provided me over the past 6 months, and helped a bike n00b make some great headway!

Bascliffe has a wiring diagram for a gl likely not to far away from your bike

https://onedrive.live.com/?id=2370B62DDF9F0C6B%211031&cid=2370B62DDF9F0C6B&group=0&parId=2370B62DDF9F0C6B%211030&o=OneUp

as for the testing I am sure someone with more experience will come along and advise.

[tom203]

The juice to each coil passes thru ignitor, so if your coil got smoked ,the ignitor circuit that controls that coil probably would not survive. Swapping known good coils and getting no spark likely says that half the ignitor is dead.

ignition coils are pretty tough, so be leery of just blaming it. It's possible that your charging system is at fault - good idea to run a quick test to be safe.

[tom203]

Buying ebay used ignitors is risky, but since your bike still has mechanical advance (I think) you can go for a dyna system like this guy did on his 650: note that pic shows the cutout required to clear oil pressure sending unit

http://www.thegsresources.com/_forum/showthread.php?233953-Transistor-Ignitor-Diagnostics-Failed&p=2209924#post2209924

[Grimly]

I recently came across a test on an ignitor - I've never tried this, but it's interesting.
Fasten a headlamp bulb into the circuit in place of the coil - turn the engine over on the starter - if the ignitor is working, the bulb should flash. It has to be a headlamp bulb of around 50/60W for the right loading.
This was a test on a spark plug site that related to testing ignitors on GM cars, iirc. Seems to me it's probably applicable enough to many ignitors of the same era.
The author made the point that a coil with a partially shorted primary can kill an ignitor (and some coils won't break down until they're hot), so you replace that, get a spark for a while, then the coil kills the new ignitor, leaving you cussing and scratching your head. If you have the slightest suspicion of the old coil, toss it out with the old ignitor.

[Matchless]

Yep, that does work, but you need to rather have 2 bulbs connected in place of the coils. You can pass a magnet across the face of the pickups in turn and you will always see only one lamp burning and as the pickups are triggered by the magnet the lamp status will change. This works like a flip flop.
The GS450 Ignitors are prone to failure due to their design, the long dwell time tends to slightly overheat the coils and eventually heat related problems occur, The ignitor also does not like to be powered by less than about 10V from a bad battery or due to voltage drops.
Usually a GS450/550 running out of spark as battery voltage drops due to poor charging soon shows signs of coil or ignitor failure.
The Dyna-S is the easiest and best replacement, but has one drawback, due to the modules not being interconnected you have double the dwell time than the original OEM ignitor. This is very hard on 30+ year old coils and although they use modern high current components also tend to fail over time. A good idea is to also fit at least 4 ohm primary coils available from Dyna I think.
Just my 2 cents!

[mike000]

Thank you everyone for the assistance. I did source a GS250 ignitor on ebay for $75, and with use of a spare Suzuki ignition coil from a friend, the bike fired right up! I was very skeptical about buying an ignitor off of ebay, however, its running great now! I guess these ignitors really are the achilles heel of the GS twins!!!