XJ900f ignition problems

Hi Everyone,
My first post on this forum, so please be kind.
I have built my XJ900f out of parts from 4 large boxes. Also acquired a spares bike lately.
I have almost everything working and today it was time to start it up. Almost all good, but no spark on cylinders 1&4. It runs and even idles on 2 and 3. I've done all the usual, even swapped coils. Coils are getting power, checked the timing coils down behind the lhs engine cover, they appear ok. Swapped out the transistor ignition box, checked continuity of all the wiring.
Surely, this is a simple thing?

 

Wiring loom issue - between the ignition module and the coil. Otherwise try swapping the ht leads (and lt inputs) between coils, the "dead cylinders" should light up. If not, pull and clean the plugs.

 

I've replaced the plugs. I think you're probably correct. Though the coil is getting power and signal. The only other thing is (as you suggested) a loom issue relating to the black earth. I noticed there is only one earth to both coils, is that correct? I will run another earth direct to the battery and see how that goes. It was running when I first assembled the bike to see if I had all the parts.
I still need a set of engine pipes as these ones are rusted out, one is a slightly smaller diameter.

 

Back again, still can't get this machine to 4 on all 4.
I've swapped the orange and grey output wires from the IC unit and the spark follows the orange onto 2&3, so coils and wiring after the IC are good.
Swapped the pickup coils and it goes from something to nothing. Ran temporary wiring from the PU coils to the IC and no change. Swapped the PU coils, no change.
That says to me I have a faulty IC unit with one track dead. Swapped the IC unit with my spare no change. Got another IC from a known machine and it's still only firing on one coil.
Is there something wrong that could be taking out half the IC unit/s?
I'm at my wits end now, starting to think up ways of putting points on it.

 

So 2 and 3 are good.
You swapped the tci wire from 2 and 3 to 1 and 4 and they sprark now?


Obviously plugs out doing this.

If so and with all your other testing it still sounds like a pickup/loom issue.

Known good tci and all.

 

just curious, what exact plugs are you using now?

 

That ground at the coil is the harness main ground, and connects to multiple ground wires within the harness terminating at a single point, sometimes with two eyelet terminals. It is just a convenient point to tie the harness grounds to the frame, so no, you don't need to add a ground to the coils

So first is was 1 and 4 not sparking, but now it is 1 and 4 sparking as indicated by the orange wire working with the 2 and 3 coil? Just an observation and maybe doesn't matter?

Do you have a DMM? You need to ohm the pickup coils and check for the correct resistance, and verify that they do not ohm to ground / chassis

https://www.xjbikes.com/forums/threads/the-ultimate-relay-switch-sensor-and-diodes-guide.27543/

from above

"XJ900RK, RL, N, FN, and F models:

Pick-up coils:
120 ohms +/- 20% = 96 ohms to 144 ohms acceptable range"

 

A shorted ignition coil would be one possibility, others not so likely would be improper wiring or battery polarity reversal along the way

 

I had a similar issue then ended up being voltage drop through the loom . When I checked the voltage at ignition coils and TCI unit with bike running I was only getting 10 volts. My solution was to make a small loom to power TCI and coils through a volt drop relay was never a problem after that . So may be worth checking circuits with a voltmeter .