Firing on one cylinder only : V-Twin Forum: Harley Davidson Forums

gsxrboy96 · 09-26-2009, 01:48 AM

Finished the motor in my buddys bike tonite, fired it up, its only hitting on one cylinder, no fire to the front cylinder, checked plugs, plug wires and volatage to coil.....everything checks out ok, can a coil go bad to where it only fires one cylinder? also bike has a crane hi4 box on it, so i dont know if it could be bad, bike ran fine before tear down? any suggestions would be helfpul. thanks chad.

TXCHOP · 09-26-2009, 02:41 AM

Without knowing more about the bike, check compression in both cyls first, than work from there. Check all connections and plug gaps,etc...

Black Magic · 09-26-2009, 09:24 AM

Wiring most likely.

gsxrboy96 · 09-26-2009, 09:38 AM

Have checked continuty in all the wires, and the motor is fresh, its a clearly visible that there is no spark to the front cylinder.

rcsoftail · 09-26-2009, 08:11 PM

Are you running single fire or dual fire. The crane hi4 will do both. You can tell if your coil has 2(dual) or 3(single) terminals for the ignition wires.

93 FXR · 09-27-2009, 10:11 AM

A buddy of mine just had his ignition module go out on him on a
ride to the Lake of the Ozarks. Only hitting on one cyl.
I believe it was a Crane system.
Replaced the ignition, and it's all good...used the same coil he had.

rcsoftail · 09-27-2009, 04:36 PM

You can check you coil using an ohm meter. Check between the neg and pos terminal and it should be 3 ohms. If it is single fire, the center terminal is the positive and you will have to check both negative terminal with each being 3 ohms.

You can also check the ohms between the spark plug terminal and the negative terminal. Can't remember the exact ohms, but it is in the thousands. If dual fire, check both spark plug terminals separately against the same neg terminal. If single fire, check each spark plug terminal against the appropriate neg terminal. The readings should be similar.

If you are running single fire, you can run a jumper wire from the front cylinder neg terminal to the rear cylinder neg terminal, remove the rear cylinder wire that goes to the ignition module and then switch the ingnition module to dual fire. If you saved your factory ignition module, plug it in and give it a try.

Also try switching the rear spark plug with the front spark plug to make sure you don't have a bad spark plug.

You can also check your plug wires with an ohm meter to make sure they have continuity and are similar in reading.

rcsoftail · 09-27-2009, 04:38 PM

Found a link for checking a coil. It's for an automotive coil, but principal is the same.
http://www.classictruckshop.com/club...e/ignition.htm

gsxrboy96 · 09-28-2009, 08:18 AM

Changed out the coil and all is well, turns out that crane sold out to s and s. and almost everything is made overseas now...went with a dyna tec ignition coil... thanks for the help.

Dr.Hess · 09-28-2009, 04:08 PM

Another ignition problem tracked down to Crane. They didn't sell out to S&S, S&S bought what they wanted after Crane went bankrupt. Why did they go bankrupt? Well, selling stuff that broke all the time sure didn't help, but mostly, from what I've seen, because a bunch of bean counters played games with it, bought the company, sold the assets off, leased them back, blew the dough and bankrupted whatever was left over of a 50 year old company. Welcome to America in the 0's.

Glad your buddy got his system fixed. A lot of people like the Dyna systems these days.