Electrical / Ignition Issues

Hello all,

82-83 Yamaha Xj750 Maxim. I'm having a problem with the electrical system. It seems like cylinders 2 and 3 aren't firing. At least it runs like crap and those pipes aren't getting hot at all. I tested the Primary and Secondary ends of the Coils and the resistance on those seems within the acceptable range. I tested the Gray and Black, Orange and Black from the TCI Unit as well. Those seem to be out according to the parts catalogue on here but within an acceptable range according to the Hayes book.

I would have done more testing but I kinda ran out of daylight having discovered the problem after replacing the seals in the Final Drive.

Kind of at a loss was hoping to get some ideas or something to test tomorrow. Could I test the resistance in the wiring harness?

 

You need fuel, spark and air. Find out which one is causing you not to get the cylinders firing. Compression test, spark test, fuel test (check fuel level from carbs)

If all are good, I'm guessing it would be the coil since 2&3 are bad. You can try swapping the coils and seeing if it's the coil itself, or the wiring from tci to the coils.

It's all about process of elimination.

 

please keep it to one thread
http://www.xjbikes.com/forums/threads/ignition-issue.115168/#post-575008


how about posting your numbers.
not that it matters but 82 or 83?
you can run your frame vin or motor vin through thislink http://www.dissingermoto.com/

your specs can be found in this link for the ignitionsystem
The Ultimate Relay, Switch, Sensor, and Diodes Guide

this test sounds like you testedthe pickup couls
I tested the Gray and Black, Orange and Black from the TCI Unit as well. Those seem to be out according to the parts catalogue on here but within an acceptable range according to the Hayes book

have you looked at the spark plugs?

ignition coil wires are red/white and orange, red/white and gray you cantest from tci but if numbers are off go to the connector at the coils and clean the connectors with electric cleaner spray and apply dielectric grease
plug and unplug a few times to seat it well

you can check resistance from tci connector to ignition coil connector

 

SOLVED! Turns out there was a connector that was disconnected.

I ran the VIN, it says the bike is an 83, but the stamp on the neck of the frame says, 10/82 so... 82 83.

I tested the coils again secondary and primary side, as well as the caps, and plugs, the carbs have fuel the plugs are decent. The fuse box is absolute garbage so I ordered a new one of those. I switched the wires and plug wires 1 and 4 to 2 and 3 and corresponding for the other coil to test if the coils were the issue, tested a whole bunch of other stuff and then noticed two wires that were disconnected near the TCI Unit. plugged them together and voila! Runs like a champ.

I rode it around the block and then decided to install my new brake hoses only to discover that two of the hoses are too short. Add sad face emoji here.

 

good to find it was a connector. bike manufactured 10/82 But sold for the market year 83

so you own a XJ750K
also known as a 1983 XJ750 Maxim