Quick Parts Question: Replacement Coils

[supertech411]

Happy New Years Guys and Gals,

I have a 1981 GS550T. Resurrected it last summer and have had a blast on it so far. Went through hell getting the carbs right, but learned a lot.
I suspect my coils (original) are not putting out a strong spark. The symptoms are a yellowish spark, and difficulty starting after sitting for a couple of weeks. The bike has factory electronic ignition, and a new stator. Could someone please tell me a good replacement coil set (make and model)? I've checked out Z1 but was a bit confused at the choices. Thanks for your help!

 

[Nessism]

The factory coils are high quality. A more likely reason for weak spark is poor voltage to the coils or worn resistor caps. Please go to Basscliff's site and look up the Voltage Relay Mod. Also check your caps using an ohm meter and maybe snip off a small piece of the high tension wire when you thread the caps back on. New coils should be the last resort unless you like spending money on your bike for nothing.

Also, hard starting after a couple of weeks parked is normal. Did you prime the carbs before trying to start the bike? Another thing that causes hard starting is valves that are too tight. How long since your last valve adjustment?

 

[doctorgonzo]

All the things Nessism said are correct. IF you do need/want aftermarket coils the 3 ohm green dynas are what you want.

 

[supertech411]

Thanks for the quick response! Believe me, the last thing I want to do is spend money I don't have to!

I have already replaced the caps with NGK units. I snipped 1/2 inch off the wire and screwed them back on. Not much improvement if any. Another symptom is that the #4 plug looks normal, but the other three foul easily. The idle screws on those three are all about 1/2 to 3/4 out. The carbs were rebuilt as part of the resurrection process and all gaskets and o rings as well as manifolds were replaced. I also sinc'd the carbs with a manometer.

Thanks again

 

[supertech411]

All the things Nessism said are correct. IF you do need/want aftermarket coils the 3 ohm green dynas are what you want.

Thanks! I'll also check out the Relay Mod on Basscliff

 

[supertech411]

Also, hard starting after a couple of weeks parked is normal. Did you prime the carbs before trying to start the bike? Another thing that causes hard starting is valves that are too tight. How long since your last valve adjustment?

The valves were recently adjusted after replacing the head gasket. I also have replaced the foam gasket on the airbox cover, and am using a stock foam air filter.

 

[gearhead13]

Compare voltage at the coils to the battery voltage and see if there is much of a voltage drop. If so I would highly recommend the coil relay mod, more power, easier starts, less fouled plugs etc.

 

[Nessism]

Sounds like you have taken care of all the common issues. Great job. One thing concerns me though, the mixture screws should be at about 3 turns, not less than one. Sounds like something is wrong. No way the bike should be rich. Hopefully the coil voltage is low and you can fix the problem.

 

[supertech411]

Sounds like you have taken care of all the common issues. Great job. One thing concerns me though, the mixture screws should be at about 3 turns, not less than one. Sounds like something is wrong. No way the bike should be rich. Hopefully the coil voltage is low and you can fix the problem.

Thank you for the compliment Just to be clear the screws I'm referring to are the idle mixture screws, which I was told only affect the low speed idle and control an emulsion flow. I had them turned out to 3 for about 5 miles until the plugs totally fouled and left me stranded.
I'm excited about the relay fix. I will add that to my winter task list which is now as follows:
1. Replace fork seals and oil.
2. Check and replace (if needed) brake pads.
3. Clean and seal gas tank.
4. Install relay mod
5. (Maybe) paint the bike dessert camo! Tank, side covers, and fenders dessert camo, wheels, pipes, and everything else flat black. Haven't made the final decision so I'm open to input from the collective on this one.

Thank you to everyone for your input and shared experience. The GS would still be taking up space in the garage had it not been for the help I received on this forum and the associated links. Safe riding to all!