Coil Mod Questions

Ok here it goes. I have a 1979 KZ1000st withe electronic ignition. on the left coil or lets say drivers side I have two connections to the coil the upper wire is black and the lower is a pinkish beige which goes into a connector and out of that connecter another pinkish beige wire runs to the right side coil lower side (these are the power wires I gather)and the upper wire is green on this coil.

My question is this when I tested the voltage with the kill switch on and the ignition on i got a 10.83 reading do you think this mod would make a difference?? I know it should be 12.00 Another question that got me a little confused is the diagram off of Wired George's site says the trigger wire is a yellow/red wire is this the wire that feeds the coils now, perhaps mine is a different color. Also I have a balast resistor which has a red wire and a pinkish beige wire will this mod bypass this resistor all together??

This mod seems easy with great results and I'm good around wires but on the other hand I don't want to start cutting at my baby anfd frig something up.

I have a wiring diagram from clymers and I could take some pics if needed.:silly:

Don't need to post the wiring diagram. The wiring on the ST is a tad more complicated from the factory than a normal KZ... The "pink" wires were probably red to begin with... they are the switched 12VDC that powers the coils. Trace them back to where they connect to the wiring harness. THIS is a DUAL OUT connector hanging over the valve cover. You can toss the pink wires. The black wire that goes to the left coil is the ignition and the right is green... left side is 1/4 cylinder pickup and green is 2/3...

OK... let's look at the ST just a tad. You didn't mention which coils you have. If you have the STOCK coils, keep in mind that this mod may not be a great idea... do some checking first. If you have Dyna or Accel coils, ignore this paragraph... the OEM coils are supposed to have 2.5 Ohms primary resistance. If you look at your battery box, there is a white 3" long ballast resistor. The theory here is that the lower resistance coils need to have the primary resistance increased with the ballast resistor. Check the resistance on the coils and the ballast resistor. The coils should have 2.5 Ohms and the ballast resistor 1.5 Ohms. Total should be 4 Ohms. To test the coils, put your multimeter in Ohms scale and with the bike OFF, touch the leads to the power and IC connected lugs on the coil. The Ohms scale should be in its lowest position... The ballast resistor should be checked by doing the same basic check with a multimeter in lowest Ohms scale with one lead on the IN power wire and the other lead on the OUT power wire.

When I tested my STs both had sets of coils where the primary resistance was really pretty high... higher than it should be and the ballast resistors were up in the 6 to 7 Ohms range. BOTH bikes gave me a total primary resistance of well over 10 Ohms meaning that the spark couldn't be decent, no matter how well powered the coils. I would suggest checking your coils and ballast resistor. If you find both in spec, the powering mod essentially could have power out and going THROUGH the ballast resistor to the coils but I wouldn't bypass the ballast resistor if the component does check out. If you find the resistance of either the ballast resistor or coils are out of spec, I would toss them both, put some Dyna green coils in and use the repowering mod.

I have standard oe coils not dyna. I understand hoe to check the ballast resistor but where do ypu put the multi meter to test the coils ??

To test the coils, put your multimeter in Ohms scale and with the bike OFF, touch the leads to the power and IC connected lugs on the coil. In other words, touch the lug with your red probe where the pink wire is connected and the lug where the black wire is connected with the black probe. Set the meter in Ohms scale. Do the same with the other coil (except pink and green).

I tested the coils they read 2.9 and 1.8

Post edited by: 2bskor, at: 2007/03/14 20:03