GS550 Starter Relay

[bill_face]

Hello all,

So i went to start my bike yesterday after a couple of months lockdown rest. Not a twitch from it. Ignotion and Oil pressure lights were on, but not even an attempt to turn over. The battery was a bit low (my trickle charger had been accidentally disconnected). I tried jumping it form a car. Still not a twitch. It usually takes quite a while to start from cold, and re-cleaning the carbs has been on my 'to do' list for some time without ever getting to it, as it its running. For this reason I didn't bother kickstarting it.

After a bit of research this morning, I have traced the problem down to the starter relay. 12v straight to the starter motor and it fires. I have 12v going into the relay, but seemingly nothing coming out (measuring voltage between output terminal and battery negative). However the input signal from the ignition button only measures ~6V. I would expect this to be 12V.

Can someone confirm what this input voltage should be? If it is meant to be 12V, could I feed 12V straight from the battery or another 12V source into the input connection to test the relay?

[Brendan W]

Input to relay coil should be no more than a Volt below battery.
Check that the relay case is earthed. The battery box may not be. I have a wire from the relay mount screw to a good earth point.
The contacts on the start button, kill switch or ignition switch could be dirty.

[Gorminrider]

Can someone confirm what this input voltage should be? If it is meant to be 12V, could I feed 12V straight from the battery or another 12V source into the input connection to test the relay?

Yes. You can test the relay with any 12V battery.

But,

The battery was a bit low (my trickle charger had been accidentally disconnected

makes me wonder. A good battery will show close to 12.5-12.6 V after sitting a month or more without being charged.

[bill_face]

So I've done some more tests and traced the problem back to a broken piece that the contacts are soldered to inside the ignition button assembly:PXL_20210307_155653152.jpg


Presumably this is meant to be in one piece. If I touch the two contacts together it fires.

The next question is whether anyone has any bright ideas for fixing this? I've looked for a replacement throttle assembly, and there would seem to be an older one on eBay UK that only has one throttle cable (mine has two).

[Gorminrider]

If you can't find a replacement right away, any spring-button switch will do...a horn button too is the same idea-very similar! and might suit.

[bill_face]

In the absense of an obvious replacement I glued the bits back together.

Now I'm struggling to figure out how this button works. I have three bits: A plastic button, a spring, and a (copper?) dome.
PXL_20210308_125309179.jpg
I'm guessing they go in the arrangement pictured, and the bit I'm holding slots in behind them. However it seems to either fire the whole time or not at all depending on whether I've prodded the copper dome bit from above.

If anyone has any insight on how to put it back together that'd be great

[Rich82GS750TZ]

Compress the spring. Then insert Tab A into Slot A.

[bill_face]

Hey, thanks for the response.

That is what I was doing, and it doesn't work (unless i prod the dome down before putting cover plate on, in which case it fires constantly)

[Rich82GS750TZ]

Seems like the little broken circuit board is FUBAR and no longer functions as a momentary switch. Folks more adept at soldering circuit boards may be able to direct you how to maybe fix it. I'd look for a used right hand control on ebay.

[Gorminrider]

The principle of the switch is that the two connections are isolated from each other until the button "copper hat" connects them against the force of the spring.
Therefore the copper "hat" needs moving as Rich' s picture shows? (there are two arrows) so that, the spring sits against the "board", and the "hat" against the plastic pushbutton-not as you show it in your picture, which would have the solenoid always on and the starter always spinning because the spring would hold the hat in contact even when the button isn't pressed

[Rich82GS750TZ]

Ah, I get it. Flip the spring/hat so the hat is against the back of the plastic button, and the dome of the hat faces the board, and only makes contact with the board when you push the button.

[Gorminrider]

right. The spring itself carries power but no circuit until the hat touches center. so best if all bits are clean. .. "naval jelly"? or Grimly's magic mix -Vinegar and salt!

[Grimly]

Grimly's magic mix -Vinegar and salt!

Not me. I use my diy version of De-Oxit, based on the original components of a 5% solution of oleic acid in a naptha carrier.

[cowboyup3371]

I may have another switch. Let me check my stash tomorrow to see