TCI failing

I have had issues with the bike just stopping in hot weather and I figured that is what it was, hot weather.
I have had the same issues now with multiple tcis in colder weather also.

For the experts, yes rooster I'm hoping you will help, I have completely rewired the harness and changed to Deutsch plugs and replaced the plug caps and coils, although the original coils had the same issue, and dare I say I've gone to extreme lengths like exhaust upgrade and barrel change plus other crazy bits and bobs.

I did replace the reg/rectifier with another but I'm wondering if a predominant AC pulse is might be the issue and I've replaced bad for bad.

So... Since it seems I have fried a couple of tcis now, what do you think would cause it?

Thankyou for reading my insanity.

 

I would guess it would be pretty hard to damage one. Even overvoltage they have an on board regulator (zener) that should deal with any extra voltage. And ii it were damaged by something like that, it would likely take it out and not make it become an intermittent failure

We always run into this when it comes to the TCI and no good method of testing other than to duplicate the issue in another bike or install one from a bike that is running well with no issues. I would gladly test it but I am thinking postage to the states and back could put a halt to that option

 

Have you verified that the brushes are ok? Mine would often shut down when I came to a stop. I eventually discovered that if I hit the brakes at idle it would shut down. I tested the voltage and found that the alternator was not putting out but about 12.8 (I think, but in any case it was low) volts and and when the brake lights came on they drew enough power to drop below what was needed to fire the plugs. New brushes fixed it.

 

Thanks for the testing offer.
I do have 2 bikes, one is good and switching the TCI in from that bike was this last test which had me writing this thread.

I'm gonna pull the alternator apart like tabaka45 has done. I have definitely had the bike just die at a set of lights and not start again, until waiting 10mins or so.

Thanks for the help. I'll update after I do some voltage tests before and after the fix.

 

Should the output voltage be about 14.5?

 

That is what the little digital voltmeter, from eBay, I stuck into the gauge cluster reads 14.5 max when I rev but I'm beyond believing it now.
It is the reason I haven't messed with the alternator. Hopefully it is wrong haha.

 

So does that mean if you switch it back then that bike runs fine over temp confirming the TCI is OK?

 

TCI seems to be running fine back in its original bike.
Very long and confusing battle with this one.
I will go through voltages, alternator and grab another regulator and do testing on all and report any findings.

I've been having issues for years and years with this bike and done a few threads thinking I'd solved it... Then it comes back. Trouble is I only ride it once a week since covid all my work is mostly remote.

 

14.5 volts is good.

 

Went through the bits and pieces.
Stator checks out at 4 ohms
Windings check out at .4 ohms between all 3 phases
Strangely the stator reads up to 15 ohms via the plug via the brushes but from the plug to the tip of each carbon brush they both read 0 ohms, which is good, so I tested the other bike and this was the same(ish)
Checked charging and my dashboard voltmeter and a multimeter attached directly to the battery. about a .5v difference higher at the battery according to the multimeter.

Charging looked good at 14.5v (ish) up to 4000rpm on the multimeter.
Let the bike run for awhile and checked the heat on the regulater/rectifier and it was pretty hot to touch (it is ambiently cool here 16C)

Revved a few more times and the multimeter is now showing voltages up to 14.7v and about 0.7v of AC irregulary, at about 2500->4000rpm.

The good bike is at about 13.8v at 2500rpm and barely gets to 14.5 at 4000rpm.

So...
The first TCI is completely dead, the one I swapped in from the other bike is functioning again though, which goes with the past cool down and works again outcome previously.

Outcome so far:
Going to track down a new regulator/rectifier. Unfortunately I gave away box loads of spares a while back, and must've given all my spares all away... oops.

Something strange:
In the wiring of the police bike, one of the phases out of the alternator has a tap going back to the dash computer.

It's point is not clear to me as the good bike doesn't even have it but the bad bike does and disconnecting it does nothing as far as I can tell, charging wise and voltage levels or on the dash.
I do wonder what it is meant to do!

 

That should be there to initiate the Computer Monitoring System (CMS) - without it or the voltage from the stator when the bike starts the CMS will remain in standby mode.

The bikes sent to the states have the same wire, but it pulls double duty and is also used to close the latching headlight relay when the bike starts

 

It is weird that it all seems to work on both of my bike without it attached although I only really pay attention to the fuel gauge normally.

I did have look at a few of the diagrams, courtesy of my xjcd, and the 650 turbo has taps all over from the alternator.

At any rate, I thank you guys for your ideas and troubleshooting.

I'll let you know how the eBay regulator turns out.

 

The fuel gauge is active with just power and does not have to be initialized. So does the CMS do the scan for faults when the bike is started?

And I did work on one TCI for a member that had an issue with and open etch where the bike would just suddenly die. It was very intermittent and would even correct itself if the power was cycled to the TCI. It finally failed long enough for me to find out it was missing power to the ASIC chip because of the poor feedthrough connection. It also turns out that in later versions this was addressed by adding more etch on the top side so as not to rely on just the feedthrough to make this connection. If your TCI matches this etch visually on the bottom (there are several versions) then it could be suspect for that same failure. I ended up adding a jumper as I didn't trust just a reflow of the feedthrough to be reliable.

 

That is very interesting, I have pulled the board from the dead TCI and will do some testing.

I dare say that I have never been comfortable with etching on both sides of a board when soldering, let alone multiple layer boards.

I gave away my cro when I started seeing smd stuff so... I blamed my eyesight haha.

Thanks for your insights, I'll get the magnifier out.

 

New regulator is in!
13.7v at idle instead of 14.5v.
Fingers crossed, I'll go riding.

 

Lol... 2 rides down.
No breakdowns.

I'm starting to feel more positive! Maybe I won't set it on fire on the side of the road one day Afterall.

Fingers still crossed!

 

Unless, touch wood, it is something else... I think it's solved.

A few more rides and all is well.

Voltage never gets above 13.9 with this new regulator, even at 100kmh.
So I'm thinking that was the culprit.

Always paranoid about taking the local tunnel though, that has no emergency lanes, since the dead stops, maybe one day I'll get the nerve up!

Summer is coming so that is this big test with ambient high temps.

Thanks for the advice, I'm going to go through the dead TCI with my new digital cro, although it can't be called that technically I guess, and see what actually popped also (rooster ftw)

 

if your bike has the headlight on permanently, that would pull the charge voltage down to the 13.9v
try taking the headlight bulb out , the voltage should rise to 14.3v, or close to

 

@Rooster53 I still have the tci in peices on my desk... A layer of dust on it now.

I apologise.

Regulator change has made me forget about it since no issues since.

@bensalf all the bulbs are led so not an issue.

So yeah... Maybe one useful outcome is that the old 40 year old regulator can fail in a non standard way.
No voltage is easy... Wrong voltage not so much.