Puzzled.

[Limeyrider]

Hey 02GF74 .... thank you very much for the detailed diagnostics .... hopefully that will give some idea of what is happening .... or not. Today is a write off as far as garage work goes .... domestics getting in the way !.
Thanks again .... I will perform the tests and give as much accurate detail as I can.

 

[Limeyrider]

Hey 02GF74 ... hope that your weekend was good.
I did some investigating today per your advice /instructions.
Checking resistance H/T lead refitted, cap and plug refitted ... # 1 coil ... 37k, #3 coil 38k, #2 AND #4 .. 0 ( ZERO ), I turned the motor over on the button the values of coils 1 & 3 dropped to 22.7k and 23.4k respectively ???.
Connected probe to orange wire and one to earth ... spun the motor and saw no reading ... BUT, my meter has a lowest setting of 600 v AC... so, probably not an accurate scale.
I am now in the process of drilling heads off screws to remove the coils / and the platform that carries the TCI unit and the servo motor. All screws are seized in their threads, and the Philips screw heads are as soft as butter. Hoping to make some progress tomorrow. I want the coils on the bench so as to get clean contacts and accurate measurements.

 

[Fire-medic]

You have an early ignition, with two pick-up coils. I suspect your pick-up coils are in a state where one is working and one isn't. Read the ohms on each one and see what you get. Follow the instructions in the service manual, your bike has a 5-wire connector for the pick-up coils, where a 1990-2007 has only two wires.

110 ohms plus or minus 15%, so 94 ohms to 127 ohms if it's OK. Disconnected, no electricity.

http://vmoa.net/VMX12-Service-Manual01.pdf

 

[Limeyrider]

Hey Fire-medic .... thank you for the photo's and notes .... I'm getting confused ... again, the manual tells me that the pick up coils are behind a plate on the crank case and are mounted on the end of the crank shaft .. ???, is what you are showing in the photo's the connections to the pick up coils ? .... sorry if that sounds dumb.

 

[Fire-medic]

Yes they are, as you said, behind the left side engine cover which is attached to the left side of the engine cases. Those are the leads you can follow them from/to the left side front-alternator cover. The pick-up coils are NOT mounted on the end of the crankshaft, they are mounted on the engine case, the stator is on the end of the left crankshaft, as it spins, permanent magnets in it are creating and breaking magnetic currents which are sensed by the stationary, not-moving pick-up coils.

 

[Limeyrider]

Hey Fire-medic ..... thanks for the explanation ... clear now.

 

[Fire-medic]

Sure you're welcome. If I made any mistake, one of the other guys will set things straight.

 

[Limeyrider]

Using the instructions in the workshop manual to check pick up coil resistance, this what I measured ... colour coded wires : Orange / Black ... 117.8 ohms. Orange / Grey ...0 ohms. Orange / White / Green .. 0 ohms. Orange / White / Red .. 3.2 ohms.
These measurements were taken from the connector that plugs into the TCI unit ...as shown in the manual.
Measuring voltage at the R/W wires at the coils and TCI unit = 11.9 volts.

Double checking the 4 ignition coils ... all average within shop manual specs. Primary .. 3.0 ohm , Secondary ..13k ohms.
Is there a method of checking the TCI unit on the bench .... without sophisticated equipment ?.... or do the measurements above indicate bad TCI unit ?

Any, and all advice much appreciated.

 

[Fire-medic]

https://www.vmaxforum.net/threads/pick-up-coil.22259/page-2#post-464890
Read this and try again.

Post #28 NY Tom:
Just to note the VMAX Factory Repair Manual is wrong on how to test the pickup coils on the older bikes. Drove me crazy looking for this thread. Book wants 110+/-10 ohms from ORANGE to all the other colors. This is incorrect! As someone stated earlier in this thread you must use the BLACK as common and check to all the others. Mark up your manual.

 

[Limeyrider]

Arrrgh !!!..... an incorrect manual ..in the hands of an electrical novice !.... disaster. Thank you for pointing that error out .... back to the drawing board. Thanks again ... much appreciated.

 

[02GF74]

To summarise.
- front coils removed - presumably because trying to connect to the HT pin using aluminium foil did it not work?
- all 4 ignition coils primary/secondary coil resistance is within spec. so no shorts or open circuit hence all coils appear to be good.
- voltage at coils is 11.1 V - previously "I have measured voltage at the R/W indicated in the manual .... 10 .7 volts" - how did you manage to gain 0.4 volts? (not that it matters but higher is better)
- resistance for HT to spark plug electorode for rear 2 coils with leads and spark plug measure correctly - I would suggest you do the same with the front so you know connection is good before refitting. them.
- starter/turn signal relay is making a noise - this concerns me but it does not appear to prevent the engine turning over nor do I see that it should affect the TCI - BTW do the turn signals flash?
- according to the Haynes manual, pick up coil (ignition switched off when measuring resistance) orange wire to each of the other 4 wires should measure 94 - 126 ohm (I'm not convinced the manual is correct) but you get very different readings - so the pick up may be bad. (hooking a 'scope when turning enigne over would show a signal)

I have looked at the wiring diagram and see the kill switch and side stand relay connected so these act as a 'cut off' for the TCI.

The only way I know to check the TCI without 'sophisticated equipment' would be to connect a red/orange/yellow/green LED and 1 k ohm resistor to the coils - see below (note resistor value, indicated by colour bands, in diagram is not 1k ohm)

If you don't have a soldering iron, then use a terminal block and screw it all together. Note I specify LED colour - don't use blue/white since they use different semi-conductor technology so may blow if connected the wrong way round. A LED and resistor can be purchased online (e.g. ebay) or from Radio Shack if they still exist. When connected as per digram, the LED should be lit and when engine is cranked over, the LED will flash but it is quite hard to see. It may well dim as the battery voltage goes down when turning over the engine but the flashes, if they happen are obvious. You can't use a light bulb instead of a LED as they react too slowly so you won't see the bulb flash.




I would suggest fitting ignition lead and plug to rear coil, wrap wire around the spark plug thread with other end of wire connected to an earthing point - then turn the engine over - there should be a spark in the gap (like what you have been doing but with a solid ground for the plug). Actually this should be enough to test (no need for LED nor 'scope) since the coil/lead/plug has been checked out.


One of the coils has a lead to the tacho, so the tacho needle should move when turning the engine over.

Regarding 'sophisticated equipment' this would be an oscilloscope. I have this one (search multimeter ET828 on ebay - a cheaper monochrome version exists) for £ 70. This my seem a lot but it has an auto-ranging DVM that is probably better than yours.

I managed to capture the signal at the coil orange wire when cranking over - see below. It normally sits at around 11 V but is switched to ground by the TCI.



The alternative is to substitute by replacing the TCI (I estimate this will be at least £ 200 or an after market version even more £££ - double that number ) and you may get the same result as there may be something else preventing a spark - note I believe Sean does a kit where you are sent various ignition parts to try out and then keep and pay for whay you need, returning the rest.

Sorry but don't know what else to suggest.

 

[Limeyrider]

Hey 02GF74.....thank you for all of the information ... some of that is over my head ... but I get the idea.

I was able to get to the front coils to get more reliable measurements using the assembled plug / cap and H/T lead ... as follows : Front left ... 22.6k Ohms. Front right 23.0k Ohms. I rechecked the rear coils with the same assembly : Rear left ... 23.2k Ohms, Rear right ... 22.5k Ohms.
I used two different plugs, and two different caps and a different ( same length ) of H/T wire ... just as a cross check.

Rechecking the pick up coils following the note from Fire-medic re the incorrect manual instruction.
I used the BLACK as common ... Right side ... W/G ... 118.9 Ohms, W/R...119.5Ohms. Left side ... Orange ... 4.0 Ohms, Grey .... 0 Ohms.
I hope that this makes sense, it looks like the Left side P/U coil is bad ?.

 

[02GF74]

I don't know circuit diagram for the pick up but it seems there are 4 coils sharing the same ground (black) wire so resistance between black wire and the other wires is the same.

It would be good if someone with a working pick up can confirm, but it does appear that yours has failed, unless the leads to it are shorted somehow.

I don't know how the TCI is designed but would expect it needs both pick ups working to produce a spark - so a replacement pick up seems the next step.

 

[Limeyrider]

Hey 02GF74..... hopefully someone can confirm the circuitry, perhaps Sean has a working coil that I could use to test the system. The contacts in the TCI unit were quite cruddy, lots of green corrosion, it scrubbed off with a fine brass wire brush in a Dremel. Thanks for your input, I will let you know how this all shakes out.

 

[Fire-medic]

Deoxit is expensive, but it cleans contacts well. I also use a Dremel, and ensure the spade M-F is a tight fit. As mentioned sometimes a squeeze w/a pair of pliers to increase the tension is necessary. There are cheap tools you can use to remove the individual wires from the nylon gang connectors, sometimes you can use a thin, small screwdriver. Make a 'pin-out' schematic before removing the wires!

 

[Limeyrider]

Hey Fire-medic .... the soft, fine brass wire brush seems to have got the male terminals clean and bright, the female terminals are a bit harder to clean, but a fine emery board, cut to shape seems to do the trick ... I will be crimping the connections too. Thanks for your input .... every little helps !.

 

[Limeyrider]

Update ..... no progress on the ignition problem ... t now appears that the starter clutch may have given up the ghost ... pressing the starter button now gives a noise like a marble rolling in a tin can ! ... much help from Sean, thanks to 02GF74 for giving me Sean's link ..... many thanks to Sean . Now need to make a flywheel puller. My Velocette Venom is not nearly as much trouble ... and it is 60 years old.

 

[MaxMidnight]

Now need to make a flywheel puller.

This is what you need.

 

[Limeyrider]

Hey MaxMidnight .... thank you for the info ... no problem making that ..... thanks again...much appreciated.

 

[Limeyrider]

A question .... what is the diameter of the centre bolt ?....I will be making from scratch and not using a " donor " puller.