Scatty Tacho

Technical questions and answers

Scatty Tacho

Postby Ells » Fri Mar 25, 2016 9:47 am

One day without an issue was perhaps too much to hope for!
Luckily I had the camera on.
Coming out of Craners towards Starkeys at about 10,500 RPM the engine goes off and the tacho goes straight to 10,000 after coasting for a bit and the tacjho moving from 8000 - 12000 it finally comes back to life and we take it steady to the melbourne loop. Exiting the melbourne loop we give it a good handfull, change up, accelerate and then a carbon copy of the first issue. As I watch the last session I can see the tacho (std yamaha) fluctuate by a couple of mm at some points going round the track.
The battery was fully charged at Lunch so we did two sessions on a 12v motorcycle battery with total loss. When the battery has run low before I have seen the tacho swinging more than it did in the last session.
As we coasted off the track to the pits there were a few spits of life from the engine. I then tried to bump it into life in the pits and it was not interested.

Apart from flat battery any suggestions?

Cheers
Mark
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Re: Scatty Tacho

Postby Ells » Fri Mar 25, 2016 7:05 pm

Recharged the battery. Gave the bike a quick look over. Nothing obvious like chaffed wires by the chain. Still does not want to fire up!

I am going to assume

1. I need to trace the grey wire from the tacho to make sure it connects with the Black/Yellow (at both CDI and PV controller).
2. Check the resistance across the pick up
3. Check the two resistances across the 3way plug from the stator.
4. Check the earth is OK for the CDI Unit
5. Swap out the CDI unit.

Is there anything else I have missed? The Power valves spin when power is turned on.
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Re: Scatty Tacho

Postby Higgsy » Sat Mar 26, 2016 8:05 am

Think you pretty much have it covered Mark

Although the static test on the stator should indicate it working and condiditon, I've had one that refused to work even though the readings were in tolerance. The one on the TZR is a fair bit out but works fine.


I take it the plugs are getting wet?
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Re: Scatty Tacho

Postby ypm76 » Sat Mar 26, 2016 11:00 am

Check your earths. Make sure your motor is earthed. If the motor is cutting out it's either a bad earth or a shagged CDI.

WHen my tacho went mental it was the connection between the PV controller and CDI but the motor continued to run normally. Same them my total loss battery died.

The clue here is your motor is affected so it's ingnition/electrics in my opinion.

The pickup wires can break internally causing issues like this too.
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Re: Scatty Tacho

Postby Ells » Sat Mar 26, 2016 1:18 pm

Cheers peeps.
Stator connection
Brown to green is 158 ohms (128-193 acceptable range)
Brown to Red is 5.0 ohms (3.6 - 5.4 acceptable range)

Pickup 231 ohms (94 - 140 is acceptable range)

Swapped pickups and going to give it a try after I earth the motor. Don't remember the motor being earthed! There is a black that comes up with the Red, Brown and Green from the stator?

Cheers
Mark
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Re: Scatty Tacho

Postby Malc » Sat Mar 26, 2016 2:56 pm

Ells wrote:Cheers peeps.
Stator connection
Brown to green is 158 ohms (128-193 acceptable range)
Brown to Red is 5.0 ohms (3.6 - 5.4 acceptable range)

Pickup 231 ohms (94 - 140 is acceptable range)

Swapped pickups and going to give it a try after I earth the motor. Don't remember the motor being earthed! There is a black that comes up with the Red, Brown and Green from the stator?

Cheers
Mark

Mark,

The black from the stator is an earth but apparently not absolutely vital. Indeed, I noticed the other day on Steve Johnson's brand new Electrex the black was not even fitted!

Re: the tacho - have you tried taking the black wire from the back of the tacho and replacing it with a heavier gauge one earthed directly to the frame at a convenient point (or even direct to the neg on the battery for test purposes)?

The 230 ohms on the pickup, although out of range, does seem to be acceptable. That said, we don't know once heat gets in there so may prove fruitful to replace it with one within range.

Finally, ditch the total loss and revert back to a charging system.
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Re: Scatty Tacho

Postby Ells » Sun Mar 27, 2016 9:53 am

After sleeping on it.

The plugs were wet when we rolled down the pit lane so at that moment the fuel was getting through. I will clean out the pilots this morning.
With the engine cutting out so quickly and the tacho swinging immediately right round I still think electrical. I have not swapped the stator yet so thats the last item to try.

We currently do get spark and compression. Will check the plugs to see if they are wet.

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Re: Scatty Tacho

Postby Ells » Sun Mar 27, 2016 7:35 pm

Rather weird thing happened this afternoon. While tidying up behind the tacho I accidentally disconnected the laptimer. Now all 12v stuff (tacho / laptimer/power valves) goes through the main power on switch.
Reconnected the laptimer, turned switch on and Power valves cycle but no sign of life from the laptimer. The long and short of it is the laptimer only works when connected across the battery. Anywhere else and it will not come on.

Is this likely to affect the bike starting and running? I assume its disconnect the battery and check resistance up and down the live circuit and the ground to find the issue? I do have a spare battery to throw in (however the CTek charger is saying all is well with the battery). The power valves are cycling ok.

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Mark
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Re: Scatty Tacho

Postby Ells » Mon Mar 28, 2016 9:48 am

So
Spare stator
Spare CDI
Spare PV controller
revereted to original pickup

To cut a long story short the 12V circuit did not work as the black wire from the stator must be the sole way of connecting the battery to ground in my loom. It was left unplugged when I connected the spare stator. I have added an extra ground straight from battery to frame.

She now shows signs of life that were not there so when it stops bucketing it down I will fire her up and swap the CDI \ PV controller \ stator back to original one at a time to see which one failed.

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Re: Scatty Tacho

Postby Ells » Mon Mar 28, 2016 12:23 pm

Firing on all cylinders :D
Just swapping things out one at a time now. Had to order some more connectors and wire as now running low.

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