85 GS550 and the spark module or the spark igniter is bad. swapped the coils from right to left to verify the coils are both good, and they are. The pick up coils also swapped and they are good. I only get spark to #1 and #4. I looked for a new module and the dealer wants $480.I found after market retros Dynatek, Boyer,and Hypertek, all about 150. any ideas on these??? or other options? Can not find used origional one on eBay evidently this is a big problem with Suzuki.

Remove spark plug, reattach spark plug wire, ground bottom of plug to bare metal on engine head and crank the ignition. If you get sparks its probably good. If you have no spark and are trying to determine if it is your magneto or coil you will have to use a volt meter.

It could be a bad coil, try swapping in a known good coil. You are checking for spark on the coil high tension cable from the coil going to the top of distributor? Also just possible the coil to distributor wire is bad.
If still no spark with a different coil and the wire is good, it could be a bad ECM. Or if you have the larger 2.6 Liter 4 cylinder engine, there is an Ignition Control Module for it that controls the coil. I don't see that ICM for the smaller 2.2 liter engine...

Do you mean no spark from the coil or distributor? Because the coil needs battery voltage to it to operate.
If you have no spark from the coil wire and you believe the wire is good or you have no reason to suspect it failing in a very short time, then before you do anything else, you should check if the small, pink wire to the little + side of the coil is a live wire (has current or voltage, and the connection is clean and tight) when the key is in on position. If no power there, the ignition switch or the wiring from the switch to the coil is bad.
If you have power to the coil, then either the coil or the electronic ignition module (inside the distributor, I think) may be bad. They can both be tested. Auto parts stores will test the ignition module for free. There are other possibilities for no spark, like a computer fault, or a bad pick-up coil, or a wiring or grounding fault, but for starters test the coil or swap in a known good one. If not the coil, check the ignition module next.
Good luck. Don't see many of those cars on the road anymore. Hope you keep it running.

Swap the coil with one of the other coils. If you still have weak spark out of that tower than replace the coil. If you have strong spark once swapped and the other coil tower now has w eak spark replace the module.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

P0300 Random Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0303 Cylinder 3 Misfire Detected
according to this fault codes first mark ignition coils
3 ---------------- 6
2 ---------------- 5
1 ---------------- 4
RB-------------LB
this right banks and left bank, please remove Ignition coils with lids and spark plugs from right bank and swap with left bank, if fault code change as
P 0304 Cylinder 4 Misfire Detected
P 0305 Cylinder 5 Misfire Detected
P 0306 Cylinder 6 Misfire Detected
You can Identify it's a faulty ignition system then next swap ignition lids from ignition coils be careful each coils have two lids one short and other long bit deference and when you remove and fix it to the car keep in mind correct order because each coil two different fire for two spark plugs don't mix up, if you mix it can create the fault code.if you detect any fault ignition coils or spark plugs or lids replace that and also whether god or bad recommend to replace spark plugs, find the right that's most important thing, if this way couldn't found the any ignition fault next step is check fuel presser, when the engine running fuel presser must be around 4.5 bar without engine running must be 4 to 6 bar if the fuel presser too low need to check two different things one is fuel pump other is fuel injectors, in this case you can swap injectors from right bank to left bank and find is the injectors leaking, if not leaking faulty fuel pump.is this information helped you? if yes please leave a comment,

I Would Say : Crank Sensor is Bad !

If the other two coils are working fine yet the other coil won't work at all [no spark out of either tower] then odds are that the ignition module that the coils are mounted on is bad. Often the module will be damaged when a coil or plug wire goes bad and the extremely high spark voltage finds an alternative path back home which is often through the body of the module This high voltage can damage the electronic components inside the module enough that it may no longer be able to drive the coil. Never hurts to double check your plug wires by substituting a couple of known good ones or swap one of the other coils around with this one but if you still don't have any spark after doing all that then it's most likely the module that's bad. Hope this helps a bit and good luck!

Not likely valve timing if it will run, cams are one piece so if one is right all are right. Have you checked compression with a gauge, or just by feel? Try swapping the sparkplug wire with the #1 cylinder and see if the dead cylinder moves with the wire. Also try moving the spark plug to another cylinder and see if the dead cylinder moves with it. If the compression is indeed good, the problem will be with the spark plug/ wire, or in the carb, these are the only things that can kill a single cylinder. The coils run a pair of cylinders so a bad coil would put out 2 cylinders at the same time. Start with the spark plug, I have seen a perfectly good looking plug, that would fire whun held to the head, but would not fire in the cylinder.

make sure the plug wireisn't grounding on sheet metal. Verify current to ignition module and that module is securely mounted for grounding. Negative side of coil to module, pos to ignition switch or starter button . Chk for current at coil +. . Coil -- should pulsate when cranking. Ensure there are no inline fuses, fuse box fuses, or fusible links incorporated into wires lesding to module. Good Luck_Ned_

MANY PROBLEMS WITH THE HALL EFFECT SENSOR AND IGNITION MODULE LOCATED IN THE DISTRIBUTOR......ALSO CHECK FOR POWER ON COIL....KEEP IN MIND THE COILS GO BAD ALOT ALSO