Pretty Nervous...Top End Disassembly

[James England]

You need to follow the pickup wires back to where they splice into thicker wire inside the wiring harness, under the engine. Also check the block connector itself that connects that part of the wiring to the loom. Buy some De-Oxit and treat all the block connectors on the entire bike. It's well worth it. Also the terminals and blocks at the black box.

[Lamric]

The pickup coil wires go all the way back to your TCI box so test the whole circuit by pulling the 4 pin plug there and stick your multimeter probes into the sockets, span either the two white or two yellow wires.

You should get 720ohms +/-20% resistance.

Now move the timing plate anticlockwise (like it would do under heavy throttle) and watch to see if your resistance reading changes indicating a break in circuit. Also try pulling on the wires while watching the reading.

[Aaron]

Can do. It will just have to be after work. Thanks again guys.

[kevxs]

have you fixed the knocking sound?

my bike knocked at idle forever. i even had 2 shops tell me my bearings were bad, turns out i just had the vacuum lines on carb 2 / carb boot 2 switched. switched them back and the knock is gone.

i also had the same shop tell me my pickup coils wires were good, when i finally got around to checking myself they were broke in 3 places.

i dont get it, they knew enough about the bike to know that the pickup wires are problematic but weren't able to tell that they were broke? WTF?

anyway needless to say i do my own repairs now.

[Aaron]

Haven't fixed the knock yet. I gotta get spark back in 1 and 4 before I can address the knock. Heck, fixing the spark may fix the knock really. But for now, im chasing down electrical phantoms. I have no intention of ever takin this bike to a shop. Even as a rookie to bike mechanics, I have more faith in myself to fix problems than any shop. Not to say there are no good shops out there, I just am too skeptical to even try em out. Plus, doing it myself is way cheaper. And more rewarding.

[Aaron]

Just to eliminate confusion, the TCI/BLack Box/Ignition brains are all the same thing right? Went out there with the multimeter and pulled the 4 prong connector on the ignition unit. It had two yellow/green stripe wires and two white/somethig else stripe wires. I set the ohm resistance range setting to 1K and checked the pins (yellow/yellow then white/white). At the pins on the ignition unit side, the multimeter read 22.5 for both sets of wires. On the connector side, it read 0. I would love to know what this tells me. Thanks in advance.

[DGXSER]

Yep TCI = Black Box = Brain Box= Iginition unit= CDI (not the same thing but a name often used).

Go to Catatonic Bugs post, find the link in his signature for the manuals and download one. It has all the testing methods for the pick up coils and such in it and will help you decipher the results.

[Aaron]

Already have the manual. Already checked the ignition and pick up coils.

[DGXSER]

OK, well, not sure on the TCI, we had a member some time ago who had a page that explained how to test the TCI, but that page is no longer at that address.

[Aaron]

Yeah, I find all kinds of older pages on here that don't exist any more. Just double checked the manual and it says " You may screw up your TCI if you test it wrong, so have a professional do it, stupid." In as many words at least. Not too helpful. Anyone able to decipher my findings?

[Aaron]

Huh...

Just went out there and hooked the ignition coils back up to test for spark again. Just for fun. Now I have spark on all four plugs! Miraculous! Now the real problem is hidden. Anyway, i put the plugs back in, pulled the choke and hit the starter. She came to life with a roar that zoomed up the tach pretty quick, so i let off the choke and it died. Tried again and was a little more tactful with the choke and got it idling. The knock is still there, but it was running with the coil cover off and the sound seemed to be coming from the vacuum advance area. Does that mean i am an idiot and really do have the vucuum line going to the wrong place? The vacuum line running out of the vac advance is currently running up to the boot on carb 2. The line running from the top of carb 2 is running to the point where all the fuel lines from the tank meet. Correct?

[motoman]

TCI is NOT all the same for all years! 78-80,same........81, its own.......82(XJ), its own...

[CaptonZap]

Just went out there and hooked the ignition coils back up to test for spark again. Just for fun. Now I have spark on all four plugs! Miraculous! Now the real problem is hidden. Anyway, i put the plugs back in, pulled the choke and hit the starter. She came to life with a roar that zoomed up the tach pretty quick, so i let off the choke and it died. Tried again and was a little more tactful with the choke and got it idling. The knock is still there, but it was running with the coil cover off and the sound seemed to be coming from the vacuum advance area. Does that mean i am an idiot and really do have the vucuum line going to the wrong place? The vacuum line running out of the vac advance is currently running up to the boot on carb 2. The line running from the top of carb 2 is running to the point where all the fuel lines from the tank meet. Correct?

Nope, that's bass ackward. The one from the carb should go to the vac advance. CZ

[Aaron]

mine is an 80. Special.

[Aaron]

CaptonZap...Thank you, the knock is gone. she idles great. Motoman...I'm sorry. You were the first to respond to the thread and the first to be right. I shoulda listened and double checked. Does this forum do reputation points? Motoman and the Capt. deserve some. Everyone else, thanks you for all your help and patience with my ignorance. But if it were'nt for ignorance, there would be no forums.