[solved]Merge ignition trigger wires and break wires?

so i just brought a pair of brake master cylinders to replace a leaking right brake. (LINK HERE)  This is not exactly the correct model for the silverwing but i cant find any new ones for my Silverwing so i brought these. the right master cylinder( front break) fits WONDERFULLY, looks great, fits great and breaks are drum tight when i pull it, it can stop on a dime. but the left break cylinder has extra wires and a different switch. because these cylinders are for honda MOTORCYCLES and not scooters theirs no ignition triggers in the left brake handle.
what i want to do is merge/solder the ignition and brake wires together to make holding the brake starts the bike
My concern is i dont want to short my system or anything, can i do this? I tried to use back the old switch, it still works but it doesn't align and can't be used.

Disableing a safety device is never a good idea, the same switch is used on various models .... https://www.ebay.co.uk/itm/Switch-Stop-Front-Fits-Honda-OE-Reference-35340-KFG-000-Each-35340-KFG-000/114499608923?_trkparms=aid%3D1110009%26algo%3DSPLICE.COMPLISTINGS%26ao%3D1%26asc%3D225076%26meid%3D4537491ce33a4c1697c57e3dc8847ce4%26pid%3D100008%26rk%3D5%26rkt%3D12%26sd%3D303380920697%26itm%3D114499608923%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3Ddefault&_trksid=p2047675.c100008.m2219

google ... 35340-KFG-000 .... for sellers local to you

You may just need to put the old (4 wire) switch on the new brake cylinder and also use the old brake handle —which has that extra tab to activate the switch.

I forgot to mention that the old switch does not align with the new handle and can't be used

There are 4 or 5 used of the correct master cylinders showing on eBay. Or why not rebuild the cylinder you have?

https://www.ebay.com/itm/Honda-2002-2013-FSC600-Silver-Wing-Scooter-OEM-Rear-Left-Brake-Master-Cylinder-/163914132696

Also check eBay for this term, “43501-MGF-305 brake”. I can’t seem to provide you with a good link for the several master cylinders shown there.

Cosmic_Jumper wrote:

There are 4 or 5 used of the correct master cylinders showing on eBay. Or why not rebuild the cylinder you have?

https://www.ebay.com/itm/Honda-2002-2013-FSC600-Silver-Wing-Scooter-OEM-Rear-Left-Brake-Master-Cylinder-/163914132696

Also check eBay for this term, “43501-MGF-305 brake”. I can’t seem to provide you with a good link for the several master cylinders shown there.

I didn't want to put a used piece back in there as there's no telling it's condition I wanted something brand new. And I also don't feel too confident about rebuilding it.

Then here is Partzilla’ page for that brand new Honda left side master cylinder: 

https://www.partzilla.com/catalog/honda/scooter/2009/fsc600d-ac-silver-wing/rear-brake-master

Not exactly cheap at ~$162 + shipping but certainly something to be very confident in.

BTW What happened to cause you to change both master cylinders?

Cosmic_Jumper wrote:

Then here is Partzilla’ page for that brand new Honda left side master cylinder: 

https://www.partzilla.com/catalog/honda/scooter/2009/fsc600d-ac-silver-wing/rear-brake-master

Not exactly cheap at ~$162 + shipping but certainly something to be very confident in.

BTW What happened to cause you to change both master cylinders?

Yeah I saw that, I brought all my pieces from partzilla but the price and the fact that I have to assemble all the pieces intimated me.

The reason I had to change them is that my right cylinder was leaking and air keep getting into the line.
I brought 2 brand new cylinders that came as a pair for $30 so I said let me just replace the left side too

My main question here is. Will my system/fuse short if I connect these wires together

No, the system won’t short. But that circuit is only meant to connect momentarily when the Start circuit is activated. Once started the circuit cuts out. If it is left permanently connected then something else might happen.

Caveat: It would be irresponsible and dangerous for someone to suggest that a separate switch be connected to those wires to be activated only when the bike is starting. So don’t do it.

Other then that I'd have weld and heavily modify the existing switch. I don't have a welding machine

I think that this is well over your abilities. Take it to a Honda shop for repairs. Brakes is not something you should be experimenting on. Come on, $30 for a pair of master cylinders? Going cheap on brakes is not going to end good. But then it is your life and you can do as you please. Good luck and be safe!!!

Cosmic_Jumper wrote:

No, the system won’t short. But that circuit is only meant to connect momentarily when the Start circuit is activated. Once started the circuit cuts out. If it is left permanently connected then something else might happen.

Caveat: It would be irresponsible and dangerous for someone to suggest that a separate switch be connected to those wires to be activated only when the bike is starting. So don’t do it.

The left brake interlock is there to ensure that when you start the bike, the brake is being held on so there are no unplanned lurches if the clutch decides to engage slightly. You could easily jumper the two wires for the starter circuit so that the brake switch is bypassed, the risk then is if you start the bike without pulling the brake on AND the clutch engages. Not a big risk for an experienced rider I would think.

Connecting the starter interlock wire through the left brake switch will not work in any case; the interlock switch is in series and feeds power to the starter button, and the brake switch connects to earth only via the brake bulbs.

Yea I tried it didn't work... The bike acts weird when I connect the wires. It did what I wanted to as in hold breaks and start as well as the back lights but a odd side effect was that the bike wouldn't turn off when I pulled out my key unless I hit the engine cuttof switch. So I can't do that. I'll just have to buy a new leaver and paint it black as well as learn to rebuild the pump in the cylinder. I can take the pump from the other new cylinder I couldn't use when it's time to do so.

Terry Smith wrote:

[Snip]
Connecting the starter interlock wire through the left brake switch will not work in any case; the interlock switch is in series and feeds power to the starter button, and the brake switch connects to earth only via the brake bulbs.

You’re going to have to school me on this.

1: Are you saying (notwithstanding the above caveat) that a separate switch for the start switch interlock (Bl/W, G/R) such as mentioned above, still wouldn’t resolve the problem unless the rear brake lever was also squeezed? And...

2: If both rear brake lights were burned out (i.e. open circuit) , or both brake light bulbs were removed, that the bike wouldn’t start?

I’m gonna have to dig out my 24” x 36” copy of the FSC600 wiring diagram to try to trace that start circuit to see how the brake light ground connection plays into the start circuit. Kind of reminds me of how the Helix (CN250) start circuit works too —which is something I could never quite wrap my head around.

I'm far from an electrical expert Tim! But the attached starter circuit diagram shows the positive feed coming from the battery via the solenoid/main fuse, to the ignition key switch then the engine stop relay, then the brake interlock, the starter button to the starter solenoid coil and finally to earth via the sidestand switch.

The brake light circuit plays normally no part in this unless you do as the OP was proposing and hooks the two circuits together.

He's just bypassing Left brake switch.  Side stand switch if working would still not allow engine to start if down.  Starter relay won't be grounded unless stand down.

Brake bulbs would have nothing to do with not starting unless some kind of short or bad ground through switch.

if my little experiment would have worked it would have been great as i still have my parking brake on before i take off anyway (i dont release that until im ready to go and is locked on parking)

XDM:copyright: wrote:

if my little experiment would have worked it would have been great as i still have my parking brake on before i take off anyway (i dont release that until im ready to go and is locked on parking)

If all you want is to be able to start the bike without the left brake switch, then you can just join the B/W and G/R wires together. No need to get the brake light circuit involved then and no funny business with the key switch.

Terry Smith wrote:

XDM:copyright: wrote:

if my little experiment would have worked it would have been great as i still have my parking brake on before i take off anyway (i dont release that until im ready to go and is locked on parking)

If all you want is to be able to start the bike without the left brake switch, then you can just join the B/W and G/R wires together. No need to get the brake light circuit involved then and no funny business with the key switch.

i could that if i wanted and completely disable the safety, i was just trying to have my cake and eat it too. ill see what i do because MAN does the new brake on the right side feel AMAZING