TOPIC:

Hey bounty, would the 4ohm coil you inked to really work? I thought the coil had to be a 3 Ohms.

(*Nevermind, I just saw on Dyna's site that you can go to a higher Ohm than stock - just not a lower Ohm then stock.*)


Good point about switching coils to see if the problem "followed" the coil. Good troubleshooting technique.

If the timing light is not lighting at all when attached to wires 2&3 you may have no spark to those cylinders. A simple test is to start the bike, pull those wires off the spark plugs, and see if the engine dies. If puuling those wires doesn't effect the engine, you're only running on 2 cylinders. Ed

shanecrow99 wrote:

Hey bounty, would the 4ohm coil you inked to really work? I thought the coil had to be a 3 Ohms.

(*Nevermind, I just saw on Dyna's site that you can go to a higher Ohm than stock - just not a lower Ohm then stock.*)

The stock OEM coils are four Ohms primary resistance. The lower Ohmic aftermarket coils are "high performance"... they also draw more current and are not at all necessary IMHO.

bountyhunter wrote:

The stock OEM coils are four Ohms primary resistance.

Not for a factory electronic ignition, those coils should read 1.8 - 2.7 Ohms on the primary.

So, have you gotten the old girl runnin' yet? I tend to agree that the prob is a bad connection. Check the bullet connectors going to the coils. A thorough electrical system inspection will oftentimes lead to a VERY simple fix. There's nuthin' worse than a classic four runnin' on only 2 cylinders!!!

OnkelB wrote:

bountyhunter wrote:

The stock OEM coils are four Ohms primary resistance.

Not for a factory electronic ignition, those coils should read 1.8 - 2.7 Ohms on the primary.

Maybe so, I have the FSM for the KZ750 with standard ignition.

One thing I will warn about: I am not sure what circuit topology is inside the Ksaki factory electronic ignition, but many of the aftermarket electronic systems us CDI (capacitive discharge ignition) and they do NOT like the low impedance "high performance" coils...... in fact, some specifically warn not to use them. The storage capacitors used are polyester type and they are destroyed when the peak discharge current gets a little too high, which can happen with the low resistance coils. I have personally fixed about a half dozen CDI units blown by using low resistance coils.

KZ electronic ignition is not CDI. It is transistorized Kettering, or flyback etc. (As is the Dyna S.)

Also, since this is an inline 4, you can easily diagnose the electrical problem by swapping the green and black wires at the coils and flip the rotor 180 degrees. If the problem (lack of spark) moves to the other pair of plugs, then Dyna S is bad or the wiring to the dead coil is bad. If the problem stays on the same set of plugs, then the coil or plugs or plug-wires are bad.

Note, previously, Dyna published 3 ohms as the minimum resistance for the coil primaries. Yours should be around 2.5 ohm (as OnkelB mentioned). This is a little low and will stress the Dyna S with more current. It may still work fine (as others have reported) but is below the safe limit set by Dyna.