xj1100 only two cylinders running ,cant find fix

As the title implies. I own a freshly rebuilt xj1100 1982 and had it running a few days. Sent it in to get the valves adjusted and all of a sudden it will only fire on two cyclinders. Was told it was the pick up coils so I found replacements( with great difficulty). Replaced and it still is doing the same thing. Are the computers known for faults on these? I didn't think they were. Any and all help would be appreciated , as I'm missing summer riding fun :-(

 

Which two cylinders are not firing?

If 1 and 2 or 3 and 4 then make sure coil wires are going to designated cylinders.

If 1 and 4 or 2 and 3 then:

Start with the ignition coil secondary resistance. Check the secondary resistance with the plug caps in place by placing the probes up inside the plug caps where they touch the metal. Check cylinder 1 to 4 - 11 kohm secondary + 5 kohm caps x 2 for 21 kohms +/- 20%, same for 2 and 3. Hopefully, they pulled one loose during the valve adjustment and you have an easy fix.

 

Compression test? would be the first thing I would do. Maybe you have some valves shimmed to tight?
If you have good compression then look at the spark. Maybe you have a bad solider joint in your ignition module. Not unheard of on these old bikes.
Hope that helps

 

It's 2 and 3 that aren't firing. One pick up coil was bad and replaced. Getting a reading of equal ohms in both now through the first connector. If I switch the main coil plugs that coil will then fire, switch back and no, so it can't be the coils. Getting a dirrent reading at the coil plug for ohms. Much different than at the first plug. Very strange cause it was working fine after the rebuild. Any other ideas?

 

So I understand this as you are switching the connectors on the primary side of the coils, and either 1 and 4 fire or 2 and 3 depending on the configuration. This would mean only one of the two channels on the TCI is working and either the TCI is defective or the pick-up coil for the non operating channel is not working.

Not sure what you are checking here. Which connector and what is the different reading?

Which pick-up did you replace?

So checking at the TCI main harness connector are you getting a reading of 120 ohms +/- 10%.

 

Concentrate on that coil and ohm it out for sure to see if its in or out of spec.
I would pop the cover on the TCI and look over every solider joint. A cracked soldier joint will give you random firing on one of the coils or not at all.

It's very strange when you swap the coil input wires it will fire and when goes back then goes dead. That kind of leads me to believe you have a bad connection from that coil back to the TCI somewhere. Thirty plus years on these cheap factory crimp connectors could be the issue.

 

I am getting a reading of 120 ohms +/-10% for both pick up coils at the first connector on the main harness. My manual doesn't tell me what the reading should be at the igniter box plug. I think the ignition coils read around the 40 ohms +/-10% at the plug.

 

I'm about to check the harness itself next and double check the TCI box again. My time is very limited is why I take so long to get back guys. Thanks for any help though. I'm missing a lot of riding time here.

 

As was mentioned earlier check compression in all cylinders.
Since you just had your valves adjusted numerous problems could have been induced during that process...bent valves, scratches valves or valve seats, improperly adjusted valves, etc...
If you compression is in spec then you might look into other things.

 

It has nothing to do with compression. There is no fire from 2,3 coil

 

send your TCI to someone with a known good running 1100 like yours.....let them test it on their bike......easiest way to confirm if good or bad....

 

The shop changed valves. See if there's any visual damage to the pickup.

Gary H.

 

I really like this idea , problem is finding another xj1100 around these parts. I'm looking though.

 

I've been at it a couple times now , the pick ups look OK. I will check the fitment of the coil wires in the coil next.

 

Start a thread asking for someone to test your tci.....you might have to send it someone stateside

 

On the smaller connector at the TCI there should be a grey, orange, and black wire. You can verify the resistance of the pick-up coils at this point just like you did on the first connector. Disconnect the connector and ohm orange to black and then grey to black and you should get 120 ohms +/- 10%, and none of the wires should ohm to chassis ground.

Ignition coil primary should be 2.5 ohms +/- 10%, forty would be way too high. You can measure them at their individual connector or at the TCI mating connector also. On the larger connector at the TCI there should be a grey, orange, and red/white wire. You can verify the resistance of the coil primaries at this point. Disconnect the connector and ohm orange to red/white and grey to red/white and you should get close to 2.5 ohms for each coil - typically on the edge or just out of spec. at this point.

Which pick-up coil did you replace?

 

Fantastic help right there! Now I have something tangible I can go by. I replaced the pick up for cylinders 2,3. I think its the grey wire. Pick up on the right side as you look at it.

 

Ok so I was able to test at the connector points you mentioned and they read within spec as you supplied info for. I guess that means the TCI is shot then? Gaahh , try to find one of these things is a needle in a haystack!

 

Dont count that TCI out yet............TCI are pretty hearty......

Start a thread asking for someone to test your tci.....you might have to send it someone stateside

 

I can test your TCI in my 1100. I think Robert can rebuild yours if need be