Weak Spark Left Coil - Firing on 1 cylinder.

[Guest]

1981 GS 450TZ - New regulator/stator/battery

Owned this bike for 5-6 years never had any problems with spark. Replaced regulator after it went bad, bike now charging fine.
Bike will fire and run on right cylinder. I can get spark out of the left cylinder, but its not strong enough to fire the left cylinder.

Right Coil reads 3.8 - 3.9 ohms on primary coil and 33 - 34K ohm on the secondary coil.
Left Coil reads 3.7 - 3.8 ohm on primary coil and 12.45k ohm on the secondary coil.

So the left coil is bad correct? That being said what is a good replacement.

Are these 3 ohm Dynateks a good replacement?

http://www.ebay.com/itm/Dynatek-DC3-1-Ignition-Coils-3-0-ohms-Angled-Single-Output-Green-Sold-In-Pairs-/171028914230?hash=item27d21e2036&vxp=mtr

Or how about the 3 ohm Mini-Dynatek coils?

http://www.ebay.com/itm/Dyna-Ignition-3-ohm-Dual-Mini-Coil-DC1-2-Wires-DW-200-Suzuki-GSXR-1100-/380694771605?hash=item58a32d3795&vxp=mtr

Additionally, is this gonna mess with my stock igniter?

Thanks for reading,
Peace&Grease

[tom203]

You got primary and secondary mixed up or it's a typo! The stock coils measure about 4 ohms primary - secondary will depend on plug cap brand/condition. Try switching coils around to see if problem moves with the coil. I'd be leery of any coils less than 4 ohms primary- the ignitor might be unhappy!
Suzuki ignition coils are plentiful on ebay

you said it's charging fine- do this simple quick test and be sure

http://www.thegsresources.com/_forum/showthread.php?164993-Charging-System-QUICK-TEST/page2&p=1272192#post1272192

[60ratrod]

try trimming back the plug wire about 1/4" and reinstall your cap to get to some fresher plug wire. could be that the wire is corroded and not allowing spark to flow efficiently. could also be a plug cap going bad too. and like tom said, you want to look at the dyna 4.0 ohm coils. you could over work your ignitor. i'm dealing with a dyna s now because I didn't know the dyna 3.0 ohm coils would cause an issue and explain a lot with the ignition issues I had

[ajkammerer93]

Recently had similar problems..

Start with replacing plug wires / boots. If that doesn't do the trick test the coils, ignitor, and signal coils.

I ended up with an ignitor problem, replaced the signal coils with a dynatech unit (which eliminates the ignitor), and replaced the coils with acel units. Running smooth now!

[elbowgreasemc]

Thanks for the replies fellas. I got her running, one of the plugs I'd recently replaced had gone bad. Also clipped a 1/4" off of the plug wire as suggested by 60ratrod.
I also found that the fuel cock gasket had gone bad and the left carb was sucking gas through the vacuum line. Luckily, I already had a petcock rebuild kit so I'm gonna replace those gaskets.
Thanks again for the advice!

[60ratrod]

Use the petcock kit as a bandade for now, but get a new petcock because that kit won't last. They fail rather quickly

[elbowgreasemc]

Use the petcock kit as a bandade for now, but get a new petcock because that kit won't last. They fail rather quickly

It was a new petcock.