Elusive electrical problems (solved)

[Bjorn]

Hi guys,

The last year I have been having all sorts of electrical troubles with my bike. It is really starting to get annoying and expensive. The past year I have run into:

• No spark (faulty TCI / repaired)
• Not charging (faulty stator / replaced)
• Fried coil ....

The fried coil is the last episode of my story. I have now fried two coils after ±10km of riding. Yesterday I replaced the coil and the bike starts up perfect. Everything seems to work but after about 8km I noticed the bike was not running perfect (popping under deceleration). At the traffic-lights it just stopped. managed to start her one more time, after coming to a complete standstill and walking home.

I dont know if the coil problem is related to the TCI and stator bit. I could really use some help to solve this. The only thing i'm not to sure about is the wiring loom. I have build a new one around one year ago. This was an upgraded version of my previous wiring loom (with decent automotive connectors etc). Could there be a link between the wiring loom and my problems? I have everything documented and could share the schematic if needed.

Here is a pic of the bike after the first coil failure, its a same to keep her in the garage during the summertime...

 

[retiredgentleman]

"Fried ignition coils".........................can you be more specific? Is each coil visibly burnt? Do they smoke or do you actually feel heat when they fail? Are you finding the primary coil to be open circuit? What brand are the ignition coils and where do you buy them?

What type of repair did you do to the TCI?

 

[Bjorn]

Fried as in shortened inside. I have not seen smoke, nor burn marks. My bike uses the single coil set-up combined with the original TCI. I purchased this coil from Heiden Tuning directly:

http://www.heidentuning.com/p/28/1854/mo74-cgp2|23=1/#17-6803-high-output-replacement-ignition-coil

I have used this type of coil for around 7 years, never any issues until now. Something else must be wrong as I cant believe coils will fail this quickly. I have not repaired the TCI myself, a hardware engineer from work did the work for me. As I understand he replaced the capacitors, as they ''age'' with time he said. He replaced a bunch of them. After which i applied new hotmelt and conformal coating.

 

[Vlad]

I think coils usually fail when the secondary winding is open. If the secondary is where the problem is, then I would suspect an intermittent grounding problem from the engine to the chassis, or from the chassis back to the battery (or somewhere else?). A bad ground might also explain the problems you were having with your charging system. Do you know if the primary or the secondary coil failed?

 

[retiredgentleman]

The #17-6803 ignition coil is a really bad coil. Many people have had multiple failures with that coil. The primary terminals break off very easily. The coil over heats very easily as well. Mikesxs has sold that Chinese coil for many years. Its just a crap coil.
Use the "Search" box that is in the upper right corner. Search under that coil number.
Get a conversation going with xjwmx. He uses a Honda coil IIRC. They can be bought used on Ebay and they're reported to work very well.

 

[retiredgentleman]

Here is a link to the thread where xjwmx talks about the Honda MP08 coil:
http://www.xs650.com/threads/honda-coil.48730/#post-495609

 

[Bjorn]

I just measured both coils. I did this according the post below from pamcopete:

1. Using the lowest scale on the meter, measure the resistance between the primary terminals with the wires removed. Should read from 2.5 to 4.5 Ohms.
2. Using the highest scale on the meter, measure between one of the primary terminals and the center core of the coil. Should be infinite resistance. (open)
3. Measure between one of the primary terminals and one of the plug wire terminals. Should be infinite resistance. (open circuit)
4. Measure between one of the plug wire terminals and the core of the coil. Should be infinite resistance (open circuit)
5. Measure from one plug terminal to the other. Should be 15,000 to 20,000 Ohms

Here is a diagram of the results :

These results are almost the same for both coils. I also inspected the coil leads and caps. I cant spot any visual damage to the leads. The resistance including 5k cap is: 1x 5000 ohm and 1x 4800 ohm.

Below a picture from the set-up on my bike. I don't measure any resistance with my multimeter between the centre core of the coil and the point where the twisted steel cable meets the frame.



Finally I have checked if the coils still works by installing it on the bike according to the pic above, feeding it with 12Vdc, removing one plug from the engine and resting it against the outside and pulling the orange wire (minus) from the coil. If im not mistaken it should create a spark when i remove the orange wire, but is doesn't.

Its good to know that this coil is not great. I will try to find one of those honda coils. Heiden tuning also supplies a pampcopete coil (green one) Are they any good? It is an option but they are relatively expensive. I want to find what is causing this first before throwing lots of money at it...

 

[gggGary]

To create spark; ground then "unground" orange wire, the spark should occur when you remove the ground. Get real fancy, put a switch in orange to ground path, should see spark when switch is opened. There are many 2.5 to 3.0 ohm primary coils that work, many have used the accel 140403, be careful you don't get an accel 140401, that has only .7 ohm primary resistance for CDI systems. Basically any dual tower coil 2.5 to 3.0 ohm primary, there are several Harley coils that are correct and some that aren't.
Get a voltmeter rigged on bike watch voltage while running. Yes that one chinese coil is crap, I found a broken terminal on a coil that was still in the factory box.

 

[retiredgentleman]

Bjorn.................You measure 0.7 ohms on the primary. That 0.7 ohms is likely just the resistance of the meter leads. The primary is
0 ohms or a short circuit. That Mikesxs (Heiden) coil is garbage.
Using a TCI you should buy a 2.5 ohm primary coil. The TCI may also work with a 3 ohm coil.
The #17-6903 coil is reported to work well. Avoid the green coil, as they produce a very high voltage, which can damage the ignition if a plug wire is left off.

If you buy a #17-6903 coil, its important to mount it so that the 2 iron core ends are connected directly to the steel frame. The frame will act as a heat sink to help cool the coil. If the iron core ends have a plastic coating, remove the plastic, so there is iron to steel contact.

 

[Bjorn]

I measured 1,1 Ohm on the primary side and subtracted the resistance of the measuring device (±0.4 Ohm) giving me the 0,7 Ohm.

I cant find the #17-6903 coil at the heiden tuning webshop anymore, seems like he only sell the crappy one. The Accel coils are also hard to find here in the Netherlands, seems to be an american brand. Maybe I can find one of those Honda coils.

This weekend I had some spare time so i spend it on finding the root cause of the problem. My gut feeling tells me that there might be a common denominator for all my electrical gremlins. Since I completely rewired the bike last summer, this is my no. one suspect because all the described issues in the opening post have occurred after the rewiring. I found this thread about ''grounding'' I find it very interesting but also hard to understand. Maybe the grounding on my bike is not OK and is causing the problem?

http://www.xs650.com/threads/grounds-so-important-a-single-point-grounding-spg-approach.41965/

I have not reinvented the wheel on the wiring of my bike and basically took the scheme below and worked from there. Right now im mapping out where all my grounding paths are. Maybe anyone from the forum can spot if there is an issue with my grounding based on that.

 

[Bob Kelly III]

To Cure the electrical problems you've been having I think I would listen to Vlad..... something is causing this and that something is probably like Vlad said..... not a good ground !

I think coils usually fail when the secondary winding is open. If the secondary is where the problem is, then I would suspect an intermittent grounding problem from the engine to the chassis, or from the chassis back to the battery (or somewhere else?). A bad ground might also explain the problems you were having with your charging system. Do you know if the primary or the secondary coil failed?

if You pull the spark plug lead and let it dangle and turn the key on and try to start it you'll fry the coil on a TCI bike
the days of pulling the spark plug lead and putting your finger in it to check for spark like you do for the tractor are over !
you can't do that without the risk of damaging something now......

Run an extra ground to the cylinder head and to the frame... what can it hurt ?
and Please remove the Paint under the grounding bolts they will render the ground useless ! (insulate it)
.....FWIW.....
Bob........

 

[Bjorn]

Hi Bob, thanks for your input. Adding a additional ground between the engine and chassis is on my to-do-list

I'm fully aware that the spark plug needs to make contact with the engine case after being removed. Regarding the ground point on the frame as displayed in the picture above, i will recheck it. I made is last year by removing all the paint, bolting all the individual ground wires to is with a bolt and applying vaseline/white petroleum jelly over it to protect is from the elements.

 

[Bob Kelly III]

Hummm.... then WHY is it acting like it's got an intermittent ground ? sounds like you covered all the bases but.... it still looks like you got an intermittent ground ( not to mention bad coils !) could the stator ground wire not be grounded ? perhaps it's metal casing not grounded
even though it's bolted on ? very unlikely but in the realm of mechanical mishaps I've seen some real strange things like 4 ground straps
on an old beat up truck and not a one worked as a ground strap ! ( Kept killing the battery and wouldn't charge !!!!)
.....can you pick up another TCI unit cheap 2nd hand perhaps ? and swap it out and see if it changes anything ?
i know their usually expensive but perhaps you could find one from gggGary he has a bunch of parts !
..... I dunno at this stage I am completely guessing..... perhaps the wire you used was defective and had breaks in it ? I've seen that happen wiring a trailer.... brand new wire and it was useless !
...... Please keep us informed on your progress ....that is a puzzling one !
....
Bob.......

 

[Bjorn]

Hi Bob,

When i have some time this week i will install a additional ground wire between the frame and the engine. I just found/ordered some Honda MP08 coils second hand.

As a matter of fact I do have a second TCI box, I have tried it and it still did not start (no spark). So i dont believe the TCI is broken.

I'll post an update asap

 

[gggGary]

Sure sounds like you had the wrong coil on there. A.7 ohm coil puts an excessive load on the TCI, the lower the ohms the higher the current it draws, not a good thing sorry to say. you need to test to be sure your replacement coil is 2.5 to 3.0 ohms. Thee are several threads on looking over the inside of the TCI for burned components, bad solder joints.

 

[gggGary]

Just yesterday me AND another member found cracked broken pickup wires, mine was down to one strand and it created an intermittent spark, bike ran fine on the lift but would break up badly under load The pickups ohmed out perfectly at 700 ohms each, then when I checked how it ran again, I had NO spark, some searching found the broken wire.
BS34 carb float setting plastic and brass floats

 

[gggGary]

And Yamaha used a frame to engine ground wire up at the head in addition to 4 bolted frame to engine connections. Bet they had a reason............

 

[Bjorn]

The measured value of 0,7 Ohm is after the failure... I did not check the coil before i installed it (lesson learned for the next time)

yeah the TCI is a vulnerable piece. But i have some confidence in the repair job my colleague did on it. I thought is broke due to vibration but he pointed out that these capacitors occasionally break ones they get older. I have access to a potting machine, so i could just pot the whole TCI to protect against the elements and vibration, but he advised against potting. Ones potted it is almost impossible to repair.
I did spot brand new TCI replacement boxes, but they are quite expensive at around 300 euro.

Thats one nice find on the pick-up on your side! nice is a way that you now something was wrong. I just got a new stator installed since is shorted out (see other topic http://www.xs650.com/threads/stator-rebuild.49460/#post-512689 ) and it came with a additional pick-up which im using right now. All the wires are brand new but I dont think i checked the resistance of the sensor itself, will do that to!

yeah my bike has the original ground between the top engine mount. Tried to make a picture last weekend but it was to dark. Did did however not look that fresh

 

[Bjorn]

Minor update:

added a additional ground between the engine and chassis. Will also replace the original one, giving met at least 2 decent ground straps.


I also received 2 MP08 honda coils (second hand but they look OK). Measured the resistance in the primary circuit, they are both around 2,8 Ohms.



next step: Im replacing all the main ground wires (battery and R/R) with thicker gauge wires. Just to rule something out. Im also planning on making a decent aluminium bracket for the coils to act as a heat sink.

 

[retiredgentleman]

Be sure to give us updates, as the engine starts running again.