ZXR750 Electrical Miss - Coils?

[Bogan]

Need some help with a miss I've got after it's been tuned, maybe you guys/girls can help me diagnose it? It's going back to the tuner on Friday afternoon in case something is loose or something like that.

It's not consistently under load or at certain revs or speed or anything. It may be only after it warms up (have to do more riding to check that one) but it may not.

How does the tacho work on these, is it just off one coil or something before the distributor or whatever they have that considers all four sparks? When it's missing the tacho dives to zero momentarily which is the dead giveaway that it's electrical because the engine is still spinning.

When it's particularly bad and sounds like it's only running on two or three if I'm sitting at lights I can smell unburnt fuel, so something is definitely awry in the bang section.

How much are coils for these and how do they let go, will they work intermittently for a while or just give up?

Any other ideas?

[timmyrocks]

ive always thought when coils go, they go.
the tacho should come off you pulse coils (they send the message to your coils) and depending what pulse it runs on may run on 1 or 2 of your pulse coils. (weeather it needs 4 signals, or 2 )

what did the do in the service is the main question?

id be looking at the spark plugs, leads, and coils are connected properly. and ecu is connected ok

also check your earths

[MickLC]

As we discussed on Friday, you need to buy a totally new loom and replace all your electrics before you even attempt to look at anything like loose connectors

[Plaz]

As we discussed on Friday, you need to buy a totally new loom and replace all your electrics before you even attempt to look at anything like loose connectors

totally agree.....I'd say get the loom for a crim and then slowly build the rest of the bike around it

[craig]

is that a "MISS " aprehension................ .....buy the loom

[jpbikeboy]

They run what's called a wasted spark setup(firing the coils on cylinders that are not on compression stroke). i wouldn't think it would be your coils as it would be highly unlikley that both would fail at the same time. The CDI is what controls the coils and the wire that comes off that also goes to the tacho. Iwould go for a CDI and see what happens.