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Summit 800R PowerTek Tachometer not working.

339 Views 7 Replies 4 Participants Last post by  nm9stheham, 
Lochnagar
Dear All,
I'm in the process of repairing a Summit 800R belonging to a local sporting estate, (low compression one cylinder requiring a top end rebuild), and now all functions correctly but for the tachometer.
The Wh./Gn. wire from pin 12 of the ECM plug to pin 7 of the tacho. plug is intact and with the engine running and tacho. disconnected I get no voltage on pin 7, neither AC or DC, with the negative meter lead to earth.
Similarly connecting a 12v. battery to pins 8 and 11, +ve and -ve. respectively then tap a +ve. via a test lamp to the RPM input pin 7 there is no needle movement.
What format is the RPM signal from the ECM to the tacho. ? Varying DC or digital pulses ? To test for the latter would require me to fire up the multi chann. Tektronix oscilloscope which is a wee bit of overkill.
Similarly what format is the actual tacho., an analogue voltmeter or a pulse sampler similar to the Krober / Motoplat as used on racing motorcycles ?
Incidentally all the lamps function as designed on the tacho. and the LCD display with the engine running.
As this model is a pull start and I'm incapable of working the manual start I've made a temporary power start using a DeWalt cordless drill with a 7/16th. Whitworth socket on the end of the drive pulley bolt .

Any help gratefully appreciated by this newcomer to this site
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N
My best guess is that white/green ought to be a pulsed tach signal if this is a 2006 PowerTek. So time for the oscilloscope! I am just guessing this from how things were typically designed in that era.

The manual says to check pin 7 (that white/green) wire for the tach signal but does not say what this tach signal is ! I skimmed through the 2006 and 2008 manuals with no luck finding that in the electrical or EMS sections .

Have you verified all the wires from the speedo to the tach? And is the gauge light in the tach working? Oh.. you answered that already. So power is getting from the speedo to the tach.
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N
And BTW, when you test that white/green wire again, if you see nothing with voltmeter or scope, then disconnect the connector from the speedo and check again. Just looking for a short on that line inside the speedo.
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Handling of motorcycles in that era was a bit scary....! No, I am wrong... it was a LOT scary!
Over 90-95 mph, my Kawasaki Triple would start shaking the steering badly. Kawasaki's solution? An adjustable steering damper Lol. Don't fix the real problems.... Just put on a band-aid.
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