Transducer and pick up combinations.

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fatnfast
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Joined: 31 Jan 2017 15:55
Location: Kent UK
Location: South East, UK

Transducer and pick up combinations.

Post by fatnfast »

My Sport has always taken a fair few kicks to get it started, but is fine once warm.

I have the later grey transducers and assumed that my pick up would be black. Checked today, and it red, so it shouldn't work well with the grey transducers according to the Dutch site? Once running, it revs cleanly, no hiccups, and starts first kick once warm.

I also found 5k plug caps had been fitted, so swapped them for 0k caps. Maybe that will reduce the 20 kick cold start up!

Am I right in thinking that I should have black early transducers fitted? Was there any aftermarket red pick ups produced that suit any transducers?

I am seriously tempted to bite the bullet and go down the Sache electronic ignition route.
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72degrees
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Re: Transducer and pick up combinations.

Post by 72degrees »

I once found out by experimentation in the car park of a French hotel which combination of transducer and pickup would at least give a spark. My K2 was on black pickup and grey transducers but I had a spare red pickup and one black transducer with me as spares (borrowed from the 375/2C) with me. It went on to one cylinder a few Kms short of this hotel. Two up with loaded Givis isn't fun on a 175 single. After much swapping of parts I discovered that a combination that at least gave two firing cylinders. I *think* I ended up with the red pickup driving one grey and one black transducer. That meant the advance was out on the pot with the grey transducer. It went well enough to get us home though.

Which type of red pickup ? I'm guessing 2nd generation with the 'magnet' like this (the same as the later black version).
Image


That suggests (if my diagnosis above was right) that the advance will be wrong on both cylinders - so at least they are matched.

Evguru will be along soon hopefully.

I recently discovered both of mine are running with 5K caps now. I'd assumed the 375 ones were non-resistor as it starts so well even when cold. I put that down to the NLM module and 2 pin coils setup (with 2nd generation red pickup) though. Mind you, it also had the stator rewound and rotor re-magnetised not that long ago.

The rebuilt 350 has the stator and rotor from a barn find 250, but that started really well with original transducers, red type 2 pickup and BPR7EIX plugs - even with 5k caps. Can't remember what the ignition winding resistance was when I tested it, just that the lighting coils were shot (which doesn't matter on a 'racer').

Unless the supply of AC to the sparks department at kickstart rpm is up to snuff you can waste a lot of time and money on changing the other components.
fatnfast
Posts: 59
Joined: 31 Jan 2017 15:55
Location: Kent UK
Location: South East, UK

Re: Transducer and pick up combinations.

Post by fatnfast »

Thank you for that, much appreciated. The starter coil has recently been rewound by NLM and the rotor has good magnatism. I think a certain amount of the prolonged starting is down to me struggling with a left side kickstart and clip-ons.
This is the transducers fitted (323982)
Image
And this is the red pick up which looks in remarkable condition. A second generation one I think?
Image

Now here's the thing. a forum member kindly donated his black 350 transducers as they did not work correctly on his bike.
Having just fitted them, it starts easily-er and revs cleanly. I have not road tested it.
EVguru
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Re: Transducer and pick up combinations.

Post by EVguru »

The red pickups have a diode in them, whilst the black ones don't, the diode being in the ignition boxes instead.

You can have two diodes in circuit and the ignition will work, but you can't have none, ie. a black pickup with black ignition boxes. You can fit external diodes though.

Each diode creates a voltage drop and the pickup is a voltage generator like the alternator (although producing a specially shaped waveform). The extra diode means you might need to spin the engine over faster to trigger the ignition boxes and create a spark.
Paul Compton
http://www.morini-mania.co.uk
http://www.youtube.com/user/EVguru
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72degrees
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Re: Transducer and pick up combinations.

Post by 72degrees »

EVguru wrote:The red pickups have a diode in them, whilst the black ones don't, the diode being in the ignition boxes instead.

You can have two diodes in circuit and the ignition will work, but you can't have none, ie. a black pickup with black ignition boxes. You can fit external diodes though.

Each diode creates a voltage drop and the pickup is a voltage generator like the alternator (although producing a specially shaped waveform). The extra diode means you might need to spin the engine over faster to trigger the ignition boxes and create a spark.
Makes sense. Does using a grey transducer with a red pickup also result in the 'wrong' ignition advance - or am I making that up?
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72degrees
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Re: Transducer and pick up combinations.

Post by 72degrees »

Definitely a second generation red pickup.

As Evguru explained, it will work a lot better with black transducers. If it still is not as easy to start as you want, consider switching to the NLM module and separate small 'scooter' coils, but retaining the red pickup as it's 'known good'. The NLM replacement pickup does seem to need a higher kickstart speed. Too high for my arthritic knees. I'm hoping neither of my red generation 2 ones pack up.
fatnfast
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Location: Kent UK
Location: South East, UK

Re: Transducer and pick up combinations.

Post by fatnfast »

EVguru wrote: The extra diode means you might need to spin the engine over faster to trigger the ignition boxes and create a spark.
That could explain the easier starting, thank you.

Like 72deg, I would be interested to know if a mismatch of pick up / transducer will adversely affect the ignition advance curve?

I'm guessing it should, but that doesn't explain why my Sport ran well through the rev range on the road with a red pick up and grey transducers? I'm assuming this from the info on the Dutch site.

I need to road test it with the black transducers now. This may prove inconclusive as they are possibly faulty, but will leave me wondering if the bike will preform so much better with a good set of black ones.
3potjohn
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Re: Transducer and pick up combinations.

Post by 3potjohn »

When you decide to replace them-sell me the grey ones please!
John
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