Stop relay

michipons

michipons

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Location
Palma de Mallorca
Hi all!

i am working on my 1200 to start it again after previous owner had it stopped for over 20 years.

The electric system was completely destroyed. I managed to isolate the ignition system from the rest of the bike to make the plugs work. I didn’t trto fire it yet.

My question is regarding the stop relay, as I understand it connects both wires from respective pick ups to stop the spark when the relay is closed.

Does it needs to receive 12V to let the engine run and when cutting the live wire it closes both wires of both pick ups and stops the engine? Or the other way around?

could somebody tell me how and where could I find an aftermarket relay that could do the work?

Best regards,
Miguel
 
The way the stop relay works on the 1200 is different to the early 3C. On the 3C it interrupts the circuit that feeds power from the dedicated ignition energising coil (in the alternator) to the CDI unit. The way it works on the 1200 is to short out the pickup coils by connecting the two wires from each pickup together.

I suspect the reason for the change is that the pickups operate at a lower voltage than the CDI energising coil, so you can use a normal automotive style 12V relay to do the job.

I don't remember the operating voltage of the CDI energising coil, but I think it's a couple of hundred volts. High voltage switching tends to produce more arcing across the contacts, so they have to be made of better material with better insulation (for "better", read more expensive). The HV contacts probably don't last as long as LV ones, so low voltage switching tends to be more reliable.

A replacement relay for your 1200 will be easy enough to source. Your local electronic/electrical/automotive supplier should be able provide a suitable 12V relay.

I know what it's called in English, but no idea what to ask for in Catalan speaking Mallorca. In English it's a "NO DPST" relay (normally open double pole single throw). Hopefully the Mallorcans have adopted the similar terminology. If they don't have a NO DPST relay in stock, a DPDT (double pole double throw) will do the job. An advantage of a DPDT relay is that you don't need to worry about the "normally open" bit because it has normally open and normally closed contacts, but there will be some redundant connection terminals that could confuse the issue if you're not used to working with with relays.

Automotive relays usually come with 6mm male spade terminals. Give us a shout if you need advice of how to wire it.
 
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Dellortoman said:
The way the stop relay works on the 1200 is different to the early 3C. On the 3C it interrupts the circuit that feeds power from the dedicated ignition energising coil (in the alternator) to the CDI unit. The way it works on the 1200 is to short out the pickup coils by connecting the two wires from each pickup together.

I suspect the reason for the change is that the pickups operate at a lower voltage than the CDI energising coil, so you can use a normal automotive style 12V relay to do the job.

I don't remember the operating voltage of the CDI energising coil, but I think it's a couple of hundred volts. High voltage switching tends to produce more arcing across the contacts, so they have to be made of better material with better insulation (for "better", read more expensive). The HV contacts probably don't last as long as LV ones, so low voltage switching tends to be more reliable.

A replacement relay for your 1200 will be easy enough to source. Your local electronic/electrical/automotive supplier should be able provide a suitable 12V relay.

I know what it's called in English, but no idea what to ask for in Catalan speaking Mallorca. In English it's a "NO DPST" relay (normally open double pole single throw). Hopefully the Mallorcans have adopted the similar terminology. If they don't have a NO DPST relay in stock, a DPDT (double pole double throw) will do the job. An advantage of a DPDT relay is that you don't need to worry about the "normally open" bit because it has normally open and normally closed contacts, but there will be some redundant connection terminals that could confuse the issue if you're not used to working with with relays.

Automotive relays usually come with 6mm male spade terminals. Give us a shout if you need advice of how to wire it.
Click to expand...
Hi!

Thank you very much for your explanations! I think there is no chance I find it on Mallorca, shops here don’t have stock anymore, wherever you go they can only check parts with frame numbers, forget about starting to explain something like this…
Could you post a link with a google result of the apropriate relay?? That would help a lot. Until now i could only find relays with two outputs, but not with two “entries”, If I can’t find it I was thinking using two relays one for each pick up?

I got lost with the DPDT explanation sorry…

regards,
Miguel
 
Ok, i was reading a bit on the web. I think i understand it.
I see also how both DPST and DPDT can do the work.
But, i can’t find it on a web shop… when I find one is for a low voltage or even 220v but not automotive 12V!
Any recommendation?
Miguel
 
Here's a suitable relay on Spanish eBay (although it's supplied from China). It's a DPDT type, 12V with 30 Amp rating.

The above relay would work OK, and it has spade terminals to connect to your wiring harness. But you don't really need 30A rating.

While the pickups could theoretically generate a reasonably high voltage (possibly up to 50V at high revs), the current output is very low. Typically less than 0.25A. So if you want a more compact relay and you're handy with a soldering iron, you could use a mini relay.
Here's a mini DPDT relay on ebay Australia. My Spanish is practically non-existent so I dunno what to search for in your part of the world.
It's rated for a switching current of 5A which is still more than enough for your application.
www.ebay.com.au

12V DPDT DIL Mini Relay | eBay

Find many great new & used options and get the best deals for 12V DPDT DIL Mini Relay at the best online prices at eBay!
www.ebay.com.au

DPDT relays have 8 pins, but you'll only be using 6 of them. If you go for the mini relay, you might also want to get a 6-pin connector plug if you want it to be detachable.

I was doing the job on my own bike, I'd go for the mini relay and wouldn't bother with a multi-pin connector. I'd simply solder it into the bike's wiring and tape it up out of the way somewhere. It's not like you'll be removing it again, unless you upgrade the ignition, in which case you'll be ripping all that wiring out anyway.

If you're not confident about wiring it up, I could grab one from my local electronics shop (Jaycar) and prepare it for you with labelled wire tails soldered onto the appropriate terminals and insulated with heat shrink, then post it off to you.

Actually, if it really was my bike, I'd take the opportunity to junk the whole CDI system and go for the ignition upgrade now. You'll get better performance and reliability with a modern ignition, and it'll be kinder to the engine.
 
Dellortoman said:
Here's a suitable relay on Spanish eBay (although it's supplied from China). It's a DPDT type, 12V with 30 Amp rating.

The above relay would work OK, and it has spade terminals to connect to your wiring harness. But you don't really need 30A rating.

While the pickups could theoretically generate a reasonably high voltage (possibly up to 50V at high revs), the current output is very low. Typically less than 0.25A. So if you want a more compact relay and you're handy with a soldering iron, you could use a mini relay.
Here's a mini DPDT relay on ebay Australia. My Spanish is practically non-existent so I dunno what to search for in your part of the world.
It's rated for a switching current of 5A which is still more than enough for your application.
www.ebay.com.au

12V DPDT DIL Mini Relay | eBay

Find many great new & used options and get the best deals for 12V DPDT DIL Mini Relay at the best online prices at eBay!
www.ebay.com.au

DPDT relays have 8 pins, but you'll only be using 6 of them. If you go for the mini relay, you might also want to get a 6-pin connector plug if you want it to be detachable.

I was doing the job on my own bike, I'd go for the mini relay and wouldn't bother with a multi-pin connector. I'd simply solder it into the bike's wiring and tape it up out of the way somewhere. It's not like you'll be removing it again, unless you upgrade the ignition, in which case you'll be ripping all that wiring out anyway.

If you're not confident about wiring it up, I could grab one from my local electronics shop (Jaycar) and prepare it for you with labelled wire tails soldered onto the appropriate terminals and insulated with heat shrink, then post it off to you.

Actually, if it really was my bike, I'd take the opportunity to junk the whole CDI system and go for the ignition upgrade now. You'll get better performance and reliability with a modern ignition, and it'll be kinder to the engine.
Click to expand...
Hi!
A big THANK YOU for all your help, much appreciated! Is all clear! I will follow your advice. I had seen that one yesterday but they seemed too small compared to the big things that Laverdas use to have😂

you are totally right with the ignition, I will probably write Red soon to order one, actually I am installing one in my 3C, and another also from ignitech in the 500! And that is exactly the problem… too much going on, for the time this 1200 will be like a post-apocalyptic bike, or a mad max bike, just want to put it on the road to ride it a bit, pass the MOT to get papers and thereafter will go to full restoration
 
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