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+--- Thread: Electronic rev counter with a magneto? (/showthread.php?tid=4948)
Electronic rev counter with a magneto? - DavidL - 14-09-2020
My godson is getting close to having his special on the road, perhaps with my coil engine and its electronic rev counter (from a 70s Triumph with a reface) but ideally with his magneto engine.
Will a magneto engine trigger an electronic rev counter in the same way as a coil engine?
If not - what's the "budget" way to get that job done? A friend is a big fan of repro chronometric smiths units for bikes, but where would we start with driving or calibrating something like that? Is a pulley drive off the fan belt an option?
Thinking "modern", is there a solution with an electronic trigger off the front pulley or the flywheel?
We're starting to understand why those authentic Ulster reps are so expensive...but are fortunate to have lemonade "special builder's" tastes to match the lemonade budget.
RE: Electronic rev counter with a magneto? - "Slack Alice" Simon - 14-09-2020
If you just want to know what the revs are, but not have it on the dashboard, there are cheap (£ 5 or so) little self powered gismos that are triggered by a wire wound round a plug lead.
Which presumable means it doesn't worry as to coil or mag ignition.
I have one, it hangs off the glove pocket lip on a little fold of aluminium, isn't attached at all and works really well.
RE: Electronic rev counter with a magneto? - DavidL - 14-09-2020
This sort of thing? https://www.amazon.co.uk/KKmoon-Engine-Digital-Tachometer-Motorcycle/dp/B009Z7RE1W/ref=psdc_303820031_t1_B000PJDMW4
RE: Electronic rev counter with a magneto? - bob46320 - 15-09-2020
Mine didn't work, too much interference ? Indicated revs were + or minus 500 or so revs, but then, I have no suppressors.
RE: Electronic rev counter with a magneto? - "Slack Alice" Simon - 15-09-2020
Yes, that's the one.
I get consistent readings and have no suppression, apart from a spare condenser across the feed to the indicator module - that may be enough to keep the spikes down.
I don't know why it is reassuring to have, but it is.
I am not getting the performance I think I should, this allows me to check if changes I make are actually doing anything, or are just wishful thinking.
Though a modern intrusion, which I don't like, the small size, black colour and mounting position make it easy to live with.
RE: Electronic rev counter with a magneto? - Mark McKibbin - 15-09-2020
You could by a tacho for a diesel engine with a sensor they are available on Ebay for about 21 GBP inc the sensor here is a link to one
https://www.ebay.com.au/itm/85mm-Marine-RPM-Tachometer-Gauge-LCD-Tacho-Digital-Hour-Meter-Backlight-6000RPM/293377870757?_trkparms=aid%3D1110010%26algo%3DHOMESPLICE.DISCCARDS%26ao%3D1%26asc%3D20200220090753%26meid%3D0518eff05ed14e0b99efd640976e8ae5%26pid%3D100009%26rk%3D1%26rkt%3D1%26sd%3D392915527098%26itm%3D293377870757%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3Ddefault&_trksid=p2047675.c100009.m1982
RE: Electronic rev counter with a magneto? - DavidL - 16-09-2020
The little digital ones look to be a sensible "tool box" item. On my shopping list.
Diesel - "compression ignition" so no points and coil - a great answer ! Am still puzzling where to take the feed. Some say "w terminal" which turns out to be somewhere in the alternator. One said "oxygen sensor". It gives us a drive unit under £20 which is brilliant.
We're likely to be refacing instruments anyway (he's quite good and quite fussy with graphics), and once I get my head round it adding a sensor (if its not a pulse from somewhere in the dynamo) is a lessor fear than a mechanical drive, or is that easier than I think?
https://www.ebay.co.uk/itm/Leyland-Marshall-255-262-270-272-285-462-472-Tractor-Tachometer-Tacho-Drive-Unit/323175287638?hash=item4b3ebf8b56:g:C5MAAOSwIrpau5WE
I suppose another good starting point might be how is the mechanical drive "done properly"?
"Tractor" and "kitcar" a fraction of "classic car" prices.