TCI Ignition R&R Options

[shutchis]

My latest post was in titled "Weak Spark", So ...

What's the best way to replace or repair my TCI Unit?

I spent the holiday’s sick and then in Vegas; Saw Elvis and almost won a Harley Davidson. I'm recovered.

I want to thank everybody for responding to my previous post; very informative. Now to business...my '82 XJ1100 still doesn't start when it’s cold, say 50F and 60% humidity.

I've checked everything, the carbs are very clean. Compression 150# in all cylinders. When it starts, it purrs; or should I say growls... this thing is powerful. Battery is new, and fully charged.

I checked the fire at the plugs, it's blue, but a weak blue. Can barely see flames it in a dark garage.

I have 12V at the coils; I ran a jumper directly to the battery.

I've read all the posts on TCI replacement. I saw where Randy Ragu is one of our many experts and technically skilled at repairing these boxes. And also I saw where some folks are looking at other options.

I'm sure my ignition is the problem. So ... What are the best ways to solve this problem? Thanks. Stan

[DiverRay]

I would start with cleaning all the connection on the bike. I used dielectric grease on mine, after I had them clean. I would then replace the spark plug caps, and cut about 1/4" off the wires. That is usually the problem area. If you want, use a DVM and check the reading on each cap, once you unscrew them off the wires. If you have one that is over 5K Ohms, just buy the four new ones. NGK still makes them, and they are about $6.00 each.
When you put the old or new ones on, put dielectric grease on the end of the wire, to form a seal between it and the cap. This will keep any energy from "leaking" to ground in high humidity.
Ray

[shutchis]

Thanks, Already replaced all the wires, the 5K ohm NGK caps, cleaned all the connections, added dielectric grease...NO JOY. I also have a two year set of 3 ohm dyna coils, and I checked all the values using a digital ohm meter, everythings in spec.

I have a friend in north Houston...maybe I can swap a TCI; see if it makes any differences.

I read in the XJ1100 service manual where the TCI protects the coils by reducing the current when not cranking or running. I think the bypass circuit is ON while I'm cranking, limiting current to the coils.

This bike runs great...when it starts!

I should have won the HD at Vegas; I'd trade-up for a new Road Star. Any other helpful hints? A Very Depressed Guy

[Ken Talbot]

I would have one more look at the small orifice in the bottom of the float bowl that controls fuel flow to the enricher circuit. Maybe try cranking it over while cold, then yank a plug before it starts to see if the plug is wet or dry. If it is wet, then you're probably on the right track thinking the problem is ignition. If the plugs are dry, it's gotta be a fuel problem. Just out of curiosity, how many turns open are your pilot screws?

[TopCatGr58]

Hey there Shutchis,

I don't know what XJ service manual you've read, and I haven't read the one copy I have, but I just reviewed the wiring diagram for the ignition circuit, and the coils get a direct draw from the 10A fuse, so that's why you're getting 12 volts at the coils. That same wire has taps for the TCI, the boost sensor, the Run/Stop switch, and a few others, but they are just common taps. The Coils power doesn't go THRU the TCI and THEN to the coils!

Now, on the older 78-79XS's, the power to coils WAS provided by the TCI bypassing the ballast resistor, to provide the full 12 volts for strong starting sparks, and once the engine was running, the TCI then shut that power supply, and routed it THRU the ballast resistor circuit so the coils then only got about 9 volts!

Yes, swapping and borrowing a TCI is a good way to verify whether your problems are TCI or fuel related! Yes, Randy is our TCI repair guru, but he's stated that aside from ensuring good soldered joints where the plugs fit into the TCI, he can't fix the EPROMS and such in the TCI's of the XJ or the 81 4RO units either!

YOu can also try some starting spray, and IF it starts more easily that way, then you can get a sense that the Ig system is working right, and that it's NOT getting enough fuel!
Good Luck!
T.C.