Weak spark on 2 and 3, strong spark on 1 and 4 HELP

I am finishing up my 81 xj750 Seca and I am having a weak spark issue on cylinder 2 and 3. I am using an inline spark tester so the plugs are under pressure when they fire and the plugs are new. So far here's what I have done. I have cleaned all the connections and removed any trace of corrosion, all the way down to the ground strap to the engine block. I found that I had a nice fat spark on 1 & 4 so I switched the leads to the coils and I got a nice fat spark on 2 & 3 so I think the coils are not the problem. I put the leads back to the proper coils. I then unscrewed all the NGK plug caps and cut a little of the wire to expose new fresh wire and reconnected the caps. I cleaned the ignition pickups and rotor. I then tested the spark again and I still get weak spark on 2 & 3. Next I tried one of my spare Ignition boxes and still no change in spark. So now to my question. How can I test the individual ignition pickups? Does anyone have any thoughts where I go from here?

Thanks

 

There is a site(I'll look for the link) that details the TCI. There are two tracks or circuits in the box, one for each ignition circuit. It sounds like you have a weak one.

btw- 190-200ohms across each pickup if I remember correctly!!

let me see what I can find for you....

jeff

 

here we go...follow the links and you'll learm more about your TCI then you ever will need!

http://www.geocities.ws/MotorCity/Speedway/7795/

http://xjbikes.com/Forums/viewtopic/p=274100.html

and the best one of all; (start here)

http://www.jetav8r.com/Vision/TCIRebuil ... build.html

good luck,
jeff

 

Pickups are 'triggers' only and the fact you have spark confirm that they work.

Are you saying that both coils fire fine when connected to a spark tester, but not when connected to the plugs/cylinders?

 

I saying that when I switched leads to the coils from the wiring harness on the bike. The coils in question had a nice fat spark when they got their signal from the cylinder 1 & 4 side of the ignition. So I know that the problem is somewhere in the ignition system that fires cylinder 2 & 3. The coil that fires those cylinders checks good. I am using an inline spark tester, with the plugs in. That way the plugs are under pressure when they fire.

 

I have identified the cause of the problem in the ignition system. It was my gauge cluster. I swapped a set of maxim gauges for the Seca ones and low and behold, the spark was nice and strong on all cylinders. The bike runs great now but I think I may have a dirty connector for something. the warning display will cycle through all the items when it starts up but it does it again when I ride it and it goes to idle. not sure why and I have checked the voltage at various rpm's and its good. Voltage never gets below 12.7 volts at idle.

I took the bike home last week and it was quite cold out and now the display does not seem to work at all not does the tach so I guess Im going to have to really clean all the connectors and see if this fixes the issue. It did not seem to affect how the bike ran though. any thoughts on this development?