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Summit 800R PowerTek Tachometer not working.

340 Views 7 Replies 4 Participants Last post by  nm9stheham
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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Dear All,
Thanks for the replies and aye Alainm, I do have the Users and Workshop manuals for a 2007 - 2008 model, .pdf format.
The owner reckons that it's a 2006 model and, with it being a Summit, it 's fitted with a combined Tacho. / speedo. with the speed shown on the LCD display. As the Mode button is broken the display shows "01h29" which I can only assume relates to an engine run time of 1 hour - 29 minutes with it having incremented to "01h32" with the engine running. Since every other function works I'm going to leave as is and fit a LCD Digital Inductive Tacho./ Hour meter with the pick up wire wrapped round the spark plug lead.
Next task is to replace the belt and driven pulley and jack up the rear to lift the track off the floor then check the LCD displays speed with the track spinning, for safety the garage door will be open and all clear in the front.

As for that Rotax engine, it would be better suited in the frame of a racing motorcycle than an off road winter bike, is there a racing class for these 800cc Skidoos ?
I've never been a two stroke fan having raced air cooled Yamahas and Suzukis and experienced the smell of burning leather when the little beggars nipped up and too slow with the clutch hand.
Little wonder the fatality rate was so high within the motorcycle Grand Prix fraternity of the 1960's '- 70's.

Thanks again Lads, now back to fettling Ducatis, a more enjoyable experience !!
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