I got a pair of ignition coils off an 1981 XJ650 that I'd like to use on my 1980 XS 400 Special - the XJ coils have two wires coming out of them, one fires cylinders #1 and #4, whereas the other gets #2 and #3 - does anyone know what the firing order for the XJ is? Do the cylinders fire two at a time, (so #1 and #4 together, then #2 and #3 together), or there is an offset in the firing time? Thanks!

The XJ650 uses wasted spark ignition, which means it sparks on every revolution wether its ignition stroke or exhaust stroke, so you could swap leads 1 and 4 over and it would make no difference to the running of the bike, same goes for 2 and 3, so firing order does not come into it.

The XJ650 uses wasted spark ignition, which means it sparks on every revolution wether its ignition stroke or exhaust stroke, so you could swap leads 1 and 4 over and it would make no difference to the running of the bike, same goes for 2 and 3, so firing order does not come into it.

Thanks Dave, that's good to know. I'd assume my XS400 also uses the wasted spark ignition? Coils are direct plug in at the harnesses.

Thanks Dave, that's good to know. I'd assume my XS400 also uses the wasted spark ignition? Coils are direct plug in at the harnesses.

The XS400 doesn't use wasted spark, but only fires at the proper time for each cylinder.

Most of the 4-cylinder machines I've had had the firing sequence 1,2,4,3.

Mainly Kawasakis, all with 'spare' or 'wasted' spark.

If you only have 2 coils, each feeding 2 cylinders, then unless the 2 cylinders are both at TDC at the same time (which I doubt) then they have to work by spare spark

Two wires = one earth out and one live in for the pulse to 'fire' the coils = spare spark ignition.

Paul

Aight, so I installed the coils and wires, plugged them in, can't get any spark, swapped the plug wires, still the same deal. Buddy says tis cause I'm using the 4-cylinder coils, he claims they make much much weaker spark than the 2-cylinder coils - does that make any sense to y'all? I mean I apparently get some sort of a weak spark as it managed to backfire through the carburetors and catch the gas-flooded air intakes on fire (very small flame, more funny than dangerous), but that 's about it, don't wanna fire the cylinders and that's that. I think I'll have to take a trip to the Yamaha stealership after all, and shell out the bucks for new coils and wires... Unless y'all got other suggestions? Also how much of a price tag shock should I expect for two coils and plug wires?

Aight, so I installed the coils and wires, plugged them in, can't get any spark, swapped the plug wires, still the same deal. Buddy says tis cause I'm using the 4-cylinder coils, he claims they make much much weaker spark than the 2-cylinder coils - does that make any sense to y'all? I mean I apparently get some sort of a weak spark as it managed to backfire through the carburetors and catch the gas-flooded air intakes on fire (very small flame, more funny than dangerous), but that 's about it, don't wanna fire the cylinders and that's that. I think I'll have to take a trip to the Yamaha stealership after all, and shell out the bucks for new coils and wires... Unless y'all got other suggestions? Also how much of a price tag shock should I expect for two coils and plug wires?

on ebay they are cheap. even online parts dealers are not to bad. should be a good bit cheaper than a dealership.