83GS550E Bad Coils?

[GQROD]

Carbs Cleaned, bench synced, vac synced, valves adjusted, mixture colortuned ran fine showed good color on plugs six months ago and has run great until noticed black soot from mufflers.

I run gas with Stabil and Seafoam since day one religiously!

Battery is Everstart almost a year old, still holds good charge, stator, rotor is new works fine, r/r is from Duaneage charges well.

Coil Relay Mod installed, relays work fine 12 volts at coils.

I only go on short under 10 mile rides, half choke for less than 2 mins to warm up, runs and idles fine.

Not as crisp to restart after running when hot. But will start.

Fuel mileage is terrible at 20-25 miles per gallon. 4.8 gallon tank, max range 100-120 miles i have gotten.

Noticed engine running rich.

Pulled plugs ( 9EA stock cold range )

Plug 1/4 are very black sooty dry.

Plug 2 insulator tan, electrode tan, plug ring charcoal greyish black.

Plug 3 Slightly sooty not as bad as 1/4

I leaned out mixture using the high idle method, plug chop at idle showed no change in color of plugs 1/4, still sooty black, but a lot less soot coming from rear mufflers.

Tested coils, primary ohms is 5 both coils. Factory specs are 3-5

HT side of coil for 1/4 is 24.5 Factory specs are 30-50 for both.

Ht side of coil for 2/3 is 25

Coils are factory stock don't know how old they are might be original to bike, Since day one spark color at plug was light blue to white and not a fat spark.

Should i replace my coils ?

[GQROD]

Forgot to mention I tested the pick up coils and their ohm values are within range.

Tested primary resistance again and they came up good 4.4 oms both sides.

I'm thinking it's the secondary on the coils that are causing the weak spark and dry soot on the plugs.

Any suggestions for replacement coils? Dyna S ? or Accel ?

[MelodicMetalGod]

I see your back at it with that bike. I'm afraid I have no particular suggestions beyond the coils, but my compliments on what is perhaps the best detail in a "diganostic question" post that I've ever seen. Well done! With that post, the experts should have plenty of info with which to start.

Best of luck!

[Marine36]

Coil readings are not perfect but they are OK IMHO. Have you tried the the plug caps?

[GQROD]

Coil readings are not perfect but they are OK IMHO. Have you tried the the plug caps?

I have not tried prying apart the plug caps since i have never done so and didn't want to damage the cables, i'll have to do a search on here and see how to test just the caps.

Thanks

[Nessism]

The caps unscrew from the wires.

Good luck and hope you figure it out.

[GQROD]

I see your back at it with that bike. I'm afraid I have no particular suggestions beyond the coils, but my compliments on what is perhaps the best detail in a "diganostic question" post that I've ever seen. Well done! With that post, the experts should have plenty of info with which to start.

Best of luck!

THANKS ! glad to see that new busa of yours hasn't kept you out of this site. Hope you have been well!

Yeah the more info the less ghost chasing readers will have to do especially since most have already gone or are going through this.

I checked my plugs today after leaning out the mixture, still no change in color although the engine did stumble then ran better with the high idle test so the carbs are working.

Ran smooth, idled fine at stops, good roll on performance, re-started fine.

I do think if it's not the caps then the coils are just not giving enough punch because the bike has run amazingly well just a tad rich on 1/4.

I re set the idle premix and will run the bike longer to see if there are any changes then get the coils and go from there unless i get other suggestions.

[GQROD]

The caps unscrew from the wires.

Good luck and hope you figure it out.

Thanks Nessim saved me a load of time during the search, are the resistance values for the caps in the factory manual?

[Marine36]

Forgot I had this link it may help:

http://www.ngksparkplugs.com/docs/Resistor_Covers.pdf

[GQROD]

Forgot I had this link it may help:


http://www.ngksparkplugs.com/docs/Resistor_Covers.pdf

Thanks! it helped a lot !

These are the readings i just got, i cut 1/4" off each wire and screwed the boots back on,

Factory Spec is 5 ohms

Plug Cap 1 = 5.02 ohms

Plug Cap 2 = 4.41 ohms

Plug Cap 3 = 4.99 ohms

Plug Cap 4 = 4.91 ohms

Just re-started the bike to let it idle and do plug chops at idle to see if this makes an improvement.

Warmed up well, shut it off, re-start is great nice and smooth, still have to read the plugs.

[GQROD]

Well looks like cutting 1/4" off the plug wires and re inserting the caps has SOLVED THE PROBLEM. !!

All plugs are now chocolate brown on the base ring, and

Electrodes are super clean !!

Had to make it richer once done due to some pinging, but it starts crisp, runs smooth and after 30 mins of idling ( with a box fan to cool it ) the plugs came out clean !! and all are even in color ! No carbon fouling !

More mix refinement may be needed once i take it for a long run tomorrow, but i'm amazed what a difference and money saving this tip was.

I do wonder if running Seafoam, Stabil and the 10% ethanol are making it difficult to get that nice light tan all over the plug rather than just on the ring base???

Hopefully i should see better mileage now THANKS everyone for your help and advice !!