1995 Aprilia Rx/RS125 ignition system

[goatblower]

can't find a replacement SEM coil yet for my RX125 so I'm going to try using a CDI system from a Honda C90 as per this article

https://www.btinternet.com/~jhpart/bkns125a.htm

I need to identify the wires coming from the bike's generator but can't get the fywheel off to take a peek.

I'm sure that the two yellows provide power for lighting etc. via a regulator which leaves me with a red, a green, and a black.

As I understand it there are two more coils in there, one producing 100 volts to power the ignition, and a pulser coil developing a couple of volts. The question is how do I connect to them? Is one of them earthed, are they both earthed? tried with a volt meter whilst turning the engine but can't be certain.

Help!!! does anyone know which is which?

thanks

[Kickstart]

Hi

Not certain that you can do this. The SEM coil is not just a coil.

It should not need anything like 100V. Just needs a small voltage on one side of the coil to build up a charge on the other side.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[goatblower]

I'll be using the C90 CDI unit and coil - it's not really a coil but a capacitor which is charged by the 100ish volts, and is 'fired' by a small voltage from the pulser coil.

I believe that the SEM system works in the same way but details are hard to come by! Hopefully the SEM generator will provide the volts!

[Kickstart]

Hi

The workshop manual does not say, but also gives nothing to check except resistance (no voltage to check with the engine cranking, etc) which suggests to me that it is a touch more complicated than you believe (if it was as you beleive it would be easy to usefully check the voltage over the coil).

If you ask Peter Knight on 0176 141 4106 he might well be able to help you.

I would mostly advise that you keep looking on Ebay. That coil about a week ago went for £7. The main failure point for this ignition system it the flywheel (magnets crack) and you will still be lumbered with that.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[goatblower]

thanks for your advice Keith - may just have located a replacement coil to try - don't have a suitable puller to get the damn fywheel off to check the magnets etc. Hope it is the coil.

£65 for a Rotax flywheel puller.

Same gadget for a Vespa (with slightly different thread size) £5!!

Looks like a trip to my mate's lathe!

[Kickstart]

Hi

£65? Yea gods they have gone up in price. You should be able to get one for a lot less than that. Is that price from Aprilia or Rotax?

If you want to make one I beleive the thread is M26 x 1.5.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[goatblower]

gettin carried away a bit there - only £50 from

https://www.skydrive.co.uk/sd_to_rs.asp !!!!!!

no one seems to list a £5 26x1.5mm - every other combination but that one!

[Kickstart]

Hi

Give Peter Knight a call. Hopefully he can supply one at a reasonable cost.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing