Another TCI question for the Gurus... :D

So here's the problem. VooDoo (the project bike, 82 750 max) will start just fine, run about 30-45 seconds and quit like the key was turned off (side stand switch is bypassed, I understand the safety issues...blah blah blah.. ) If I turn the key off / on try to start, it will start again after an indeterminant number of off-ons. Once it starts it will run again for about a minute then quit....same routine. After 2-3 rounds of this it will start and run just fine for hours on end. I should mention that when it's in the run-quit mode, she seems to idle a little rough, but when she kicks into the 'run and keep runnin' mode she purrs like a kitten.
So...I'm thinking I need to take a look at the TCI, maybe replace transistors...at least pull it apart and give it a visual. I pulled the cover off and noticed that one of the transistors (I'm assuming it's a transistor since it was opposite the heat sink screw in the backside..) has a jumper between two of the legs, while the other transistor (across from the other heatsinnk screw) doesn't have this. Here's some pic I hope will help. I'm thinking I should snip the 'jumper'. It doesn't appear to be scrap that just got stuck there...but maybe it is...

Here's where it is on the baord in general..


It aligns with this ...


Coupls close ups..



what's the verdict guys... get rid of it and put it back on the bike ? I don't want to chance creating other bigger problems, so I figured I would check with the experts...

 

That "jumper" looks like dirt or corosion. I don't think your problems are TCI related.
Your sumptions point to a short in the saftey circuit. There is a saftey circuit relay that is driven off the side stand switch. Have you unplugged it? Bypassing the side stand switch won't bypass that relay, unplugging it will. The relay is either under the tank right above the carbs or behind the tank under the seat. Find that relay before taking the TCI apart.
If you are up to it there are some diodes in the TCI that are prone to corrosion and can be replaced.
http://www.xjbikes.com/Forums/viewtopic/t=32519.html

 

Ok...so from what Chacal has...

The small square relay under the TCI and rectifier is the sidestand relay...and I can just unplug this and the bike will still start eh..?




The only thing that is bothering me though, is the change I hear in the idle...I would think if the ss relay was the problem I wouldn't have a rough/smooth idle show up..it would be run or no run, smooth idle all the time.....

I'll give it a shot though. I'll clean the crap off the relay legs and remove the relay ...(and in the words of the Terminator..) " I'll be bahk..."

 

The ss relay can and do get moisture trapped inside and will cause the idle to stumble. The engine vibration in combination with the corrosion inside the relay makes this happen.
Unplug the relay and see what happens. The relays do come apart easily to inspect.

That relay is the reason I got my V-Max cheap. The PO was tired of paying a service shop to find out why the bike was cutting off. Also got a Venture parts bike for the sams reason.

 

I'm baaack !
I cleaned the 'scab jumper' off and then I took the ss safety relay out and it seemed to eliminate the problem...I'll know better when I get some ride time in later today, but the prognosis looks good! Thanks Mlew....

 

(snip)

(more snippage)

So you still don't know which it was... TCI or the SS relay. I'm doubtful it was the TCI, though, for this reason: if the TCI is the culprit, as it was in my case, the problem usually isn't in the transistors (a failure of one would cause two cylinders to not fire, IIRC) but the capacitors. Plus, there's a coating on the PCB that insulates the board, so I'm thinking it's doubtful anything on the surface would cause the two connectors to short.

Just for gits and shiggles, I'm attaching a pic of the component side of the unit.

 

I had an similar issue. Even after jumping the circuit at the switch
prob kept returning.

Then I jumped it at the connector-prob solved. Why?
Because when I pulled the no longer needed ss switch and harness
from the frame I found a nice hole had rubbed through the wires.
Over the years of riding the frame wore through a spot where
you could not see it. 8O

 

nope... I have always been too impatient to experiment one step at a time... :lol:


I had bypassed the ss relay right at the plug, not at the switch, and I still had the intermittent problem.



Just got back form a ride and she ran great! Started right up with no cut-out at all, which it was always doing when starting cold. I'll check again tomorrow, but it's looking like the relay was the problem .. (guess I should have listened to you guys about a week ago.. ... my bad )

 

I've been having this same exact problem with my 82 xj650 maxim. Kickstand safety switch and clutch switch are no longer present. (Might I add that the neutral light is always on, no matter what gear I'm in) I unplugged the ss safety relay, yet the problem still occurs. I start it cold and let it idle and in a few minutes it will cut out. Whether it wants to start back up or not is either hit or miss. It will run fine for hours, then all of the sudden it will cut out and leave me stranded on the side of the road until it feels like starting again. I ohmed out the ignition coils and pickup coils, theyre good. The only thing i can think of is the TCI box. When the killswitch is off, the bike will not turn over. But when this problem occurs, the bike will turn over, but has no spark.

 

Tried taking the relay switch out of the mix...and I still had the problem intermittently.....yeah XJBob...I have come to the conclusion that it most likely is my TCI box. I have noticed that sometimes when I start it, she runs fine but one of the cylinders sounds like it's firing 'weakly' (that's the best way I can explain it) If I take off with it will spit and sputter a tad until rpms get to about 4k, then everything runs smooth. When that happens it will usually die within the next half mile. BUT...when she starts (cold or hot) and purrs like a kitten, then it never fails. One of the first things on my to-do list is replace/have someone fix my TCI....wasn't there someone on XJbikes who does that on the side...?

 

Yes, his name is Robert, he's one of the forum moderators. I just sent him a PM

 

Robert hasn't been here in a while; I poked him via email a few weeks back, and he's been extremely busy, from what I gather.

 

You should have a CLOSE look at the TCI Board
Use a Magnifying Glass or a Jewelers Loop.

Examine the Lines of the Printed Circuit.
Repair any Hairline Fractures or suspected Shorts.

You seen to have the proper skills and tools.

Replacing the Transistors is a Low-cost Upgrade.

Interesting How-to:
http://dave_jack.tripod.com/id41.htm