electrical problem?

just finished rebuilding the carbs and putting the valves in spec and went to start it to vacuum sync and it won't start. i turn the ignition and neutral indicator comes on, flip the kill switch to on and i hear the "click." it cranks over repeatedly but won't fire up. battery voltage is 12.8 volts...when cranking it drops to about 10.5 i did disconnect most of the harness plugs in order to clean them so that may be an issue, but i did go over a lot of them afterward to check for continuity. i just noticed i have no spark on any cylinder. other things i've checked/done recently: replaced alternator brushes that were borderline. checked rotor and stator resistance. while trying to learn the wiring i noticed i can't find any sidestand relay...it's gone (maybe that's why i've ridden away with it down before!) and the wiring that did go to it has been twisted together to disable it. i also tried to follow some how to advice from SQLGuy's post http://xjbikes.com/Forums/viewtopic/t+21932html and found some wierd results. using a voltmeter, i found appx 11.5 volts between the red/white and black TCI wires with ignition on (which he states is just barely within range) and 8.5 when cranking, which indicates it could be a number of problems. also when verifying the safety cutout, with ignition off, i have continuity and no resistance. when i turn the ignition on resistance goes up slightly, but when i turn the kill switch to on it becomes an open circuit. sorry this is so long and confusing, i just want to put all the background info out there.

 

update...just put in a brand new battery and still won't start.

 

Do you still have a stock fuse box? If so, check the condition of the clips for the ignition fuse, and the fuse itself. The stock fuse boxes are notorious for their oxidizing clips that become brittle and non-conductive.

 

SQLGuy, i removed the stock box and just put in some in line glass fuse holders a while back. eventually, i'll make the upgrade to the blade style fuses. i do have continuity on both sides of every fuse...should i test that with a load? what confuses me though is that the bike was running before i took it apart. it wasn't running the greatest but still ran at least. sort of leads me to believe that it's something simple like a connection that i messed with. but, i'm the first to admit i know next to nothing about electricity...except that it shocks the he## out of me. great post about ignition troubleshooting. it's a little over my head but i'm understanding it slowly and have learned a lot. thanks

 

Yes, definitely test to see whether the fuse is dropping voltage when cranking, and also see whether the voltage at the TCI is still dropping to 8.5V with the new battery.

The other thing to do would be to disconnect the Black/White single wire bullet connector that comes off the 6-pin plug on the TCI. This is the safety shutdown that would normally be switched by your sidestand relay.... just in case the bundle of twisted wires isn't twisted quite right.

 

Courtesy Len Chacal

http://www.xjbikes.com/Forums/viewtopic/t=27543.html

 

Adrian, thanks. I've been using that guide to help eliminate possibilities. Sqlguy, I did try pulling the black/white wire bullet connector with no change. What type of voltage drop is acceptable across the fuses and do I just need to have the probes on each side of each fuse. I haven't tested the voltage drop at the tci yet but will tonight. Also, coil resistance checks out.

 

Voltage drop across the fuse should checked with the probes on the clips, or on the wires attaching to the clips. Voltage drop there, under load, should probably be 0.2V or less.

 

ok, with new battery installed i still have the voltage drop at r/w and black wires at tci. drops to 8.5v, same as old battery. also, i found substantial resistance in the on/off switch so i removed it and cleaned everything, put it back together and now .000 ohms there. the ignition harness connector plug was also melted and corroded so i replaced that. then, i decided i would take the ignition switch apart and clean it as well. it was corroded also. now, when i put it back together it doesn't do anything. i thought i put it back together the way it came out but obviously not. any advice? i've removed/installed it multiple times and can't get it to work.

 

ok, ignition switch is working again. i reinstalled it incorrectly. after cleaning it, just like the kill switch, no resistance is registering on the meter. so, that eliminates the ignition switch and the kill switch as problems...i think. also, voltage drop across the ignition fuse is .1volts so that seems to check out. so, now i'm at a complete loss as to what to look at next. and i'm sure the neighbors are tired of hearing me yell every obscenity imaginable at the top of my lungs.

 

have you checked your solenoid switch? from battery follow positive lead to switch. if switch is bad it will turn over but not start. it happened to mine

 

Have you checked you actually get spark while cranking?

Pull a plug and stick it in the boot, hold the casing against the engine and crank. If you see orange spark or no spark, you've got a voltage problem most likely.

Also, let us know the condition of the plug when you pull it, is it soaked with gas? carbon fouled?

 

MJDeder, i'm not 100% sure how to test the solenoid switch. is that the same as the starter/ignition/cut-off relay...if so, my color wiring doesn't match the factory diagrams but i have very little resistance between any of the terminals, whether with main (ignition) switch on or off, engine run/off switch off or in run position, or starter button depressed and starter turning engine. the resistance i'm showing between terminals is nowhere near what the factory book shows when the relay is bad. all terminals to ground check out as well. this relay "clicks" when i turn the "engine run/off switch" to run if that is the same you're talking about. if i unplug this relay the bike won't even crank over at all. when jumping the solenoid itself the bike still turns over but doesn't start.

KrS14, i have no spark on any cylinder. leaving all spark plugs in i disconnect one plug wire at a time, install a clean/new spark plug into plug, press/ground it to valve cover and crank it over and no spark on any cylinder. i just put new plugs in after doing carb rebuild and valve adjustment so they're new and haven't even started the bike yet...my old ones, before all this work were lean 1,4 and had heavy carbon on 2,3 i'm hoping the carb work fixes that.

 

Ok, so it's somewhere in your ignition system. Next thing i'd do is check your readings on the pickup coils, and main coils, primary and secondary sides.

**resistance between any of the terminals, whether with main (ignition) switch on or off**

I hope you're doing this with the battery removed/disconnected. Trying to measure resistance with a powered circuit = blown meter.

 

pickup coils are within spec. earlier in this post i mentioned that ignition coils are within spec...after retesting i'm not sure...just to be sure of all the details to make sure i'm doing this correctly i'm testing coil for 1 and 4 with plug caps removed, probes into spark plug wires and show 15K ohms, which the manual says is high. and then coil for 2 and 3 i'm testing at rear terminals of coil where wire exits harness and am getting 2 ohms, which is low based on manual specs. so based on this, both coils are testing out of spec. next question. how does a bike go from running, to being garaged for carb and valve work, and then after that work is finished i try to start it and have two bad coils? do coils fail suddenly or over time? the reason i ask is i'm wondering if what i thought was a "fuel issue" that has progressively gotten worse over many months could have been the coils slowly going out of spec. thanks

 

If you're still seeing voltage dropping to 8.5V at the TCI, then that's where we need to start more diagnostics.

Are you still seeing this?

If so, where are you connecting the ground probe for the meter? Check with ground at chassis, ground at the TCI's Black wire, and ground at battery -, to make sure whether or not there's a grounding issue here.

If you are still seeing 8.5V regardless of where you probe for ground, then you still have a voltage drop problem on that supply. You can isolate whether this is a real cause of the issue by running a jumper wire from battery + to R/W at the TCI (using a Radio Shack 'gator jumper, for example).

Let us know what you find.

 

yes, i'm still seeing voltage drop at the tci down to 7.9-8.3 volts. i just tested what you recommended and am seeing the same reading with ground probe at battery, tci black wire, frame near the coils, and alternator cover. i'll go try jumping from pos battery to r/w wire at tci right now and let you know what i find.

 

ok, just jumped from pos battery terminal to r/w wire at tci and my voltmeter reads 10.7 volts.

 

Is that while cranking?

Are you getting any spark now?

 

yes, that's while cranking. unfortunately, no spark though.