84 GS550L coil problems

[Guest]

What would cause the same coil #2-#3 to keep frying? I've burned up 3 in a very short time like 3 days. I've changed the timing plate or CDI, I've tried 2 different moduals. Any ideas?

The bike only has 2,900 original miles on it.

[tom203]

When you put a new coil in, does bike run OK until burn out? Have you checked to make sure that when ignition is off, no power is going to coils?

[Steve]

Maybe changing the "CDI" is the problem?

Especially since there isn't one on the bike.

.

[Nessism]

Been around here for a while now and this is the first claim of a bike that burns out coils like you state. Only thing that comes to mind is a failed regular/rectifier unit may be allowing your stator to pump high voltage battery power into the system, thus burning out components. When this happens head lamps often burn out and the battery electrolyte boils off, destroying your battery. Never heard of this burning out coils though, although you never know sometimes.

[Charley Davidson]

Bike runs great for a short period of time then starts running on 2 cylinders. Always the same 2 cylinders. Bike has been sitting in storage 25 years.

[Nessism]

Bike runs great for a short period of time then starts running on 2 cylinders. Always the same 2 cylinders. Bike has been sitting in storage 25 years.

The coils are generally very reliable, as are the signal generators. Ignitors less so but not failure prone. Voltage to the coils is suspect with old bikes, and the R/R very suspect, although again, it would be unusual for coils to burn out like stated.

If you are loosing spark first thing I'd check is coil voltage (assuming the charging system is not over charging as mentioned previously). You should be getting at least 11 volts at the coil. Make some jumpers and try switching the coils side for side to see if the fault switches sides along with the coil. If the coil is truly bad, just pick up a new used one. You bad luck is bound to stop soon since again, these are generally high quality parts and not failure prone.

[Steve]

Are you SURE it's the coil that is failing?

If you have changed the coil multiple times, it might be the ignitor that has failed.

Less-likely would be the signal generator.

By the way, what bike is this for? The thread title says " '84 550L", your signature says " '81 550L".

.

[Charley Davidson]

Are you SURE it's the coil that is failing?

If you have changed the coil multiple times, it might be the ignitor that has failed.

Less-likely would be the signal generator.

By the way, what bike is this for? The thread title says " '84 550L", your signature says " '81 550L".

.

84 GS550L I picked up another one. And may get 2 more. Although I'm not a big fan of these bikes they seem to find me and follow me home.

[Nessism]

My bad on thinking this was for an '81 and not '84. Guess I should read the title and not look at the persons signature...

At any rate, the 2nd generation 550 ignitors are failure prone. Unfortunately, there is no direct replacement either. The ignitor controls spark advance and I'm unaware of any aftermarket kits that fit that application. Not positive as to what's going on, but money down on an ignitor issue, not a coil issue.

[Charley Davidson]

Today for a few seconds or so it started running on all 4, the unexpected power will snap your neck like a squirt of nos.
Will too much gas to those 2 cylinders cause it to foul the plug. And will a fouled plug fire? @ reasons I ask this is one I'm using a ton of gas (like on reserve in 30 miles) and had same issues with same carbs on my other bike (Intermitently running on 2 cylinders and using way to much gas) carbs were rebuilt last year.

[JEEPRUSTY]

Check you plug caps
unscrew the wee brass insert on the inside and be suitably shocked when you
(most likely ) find rust and corrosion inside.

[JayWB]

If the spark plug cannot fire normally but you persist in running the engine anyway the high energy of the spark has to go somewhere.

It'll usually destroy a coil. Check your spark plugs, plug wires and plug caps.

[Charley Davidson]

Fixed

Found the issue, it was the connector at that coil. I just cut out the connector and hard wired it, I did the ground first but had to do both, now I need to see if I get reasonable gas mileage or if I have another issue.

Thanks for all the help.