ignition

[Martin6]

Morala.

As a starter(pardon the pun), I recommend you remove and open the starter solenoid. Check to make sure the post moves freely and that the horizontal copper bar is not fused across the solenoid contact posts. If necessary you can flip the bar over to provide a nice set of fresh contacts.

👍

[Morala]

thanks for all your help,tried the bike today started without any problem so will leave it to see if the problem happens again,wont be using the bike over the winter so gives me time to keep an eye on it thanks again for all your advice.

[Bryanj]

If the solenoid stuck once it will again so probably worth changing, they aint expensive

[McCabe-Thiele (Ted)]

Personally, I think  that's a problem that needs sorting, not ignoring in the forlorn hope it will go away. For the relatively modest cost involved I would start by replacing the solenoid.
  ,
You stated it went on to flatten the battery with the ignition off, that could end up as a damaged battery or a burnt out starter motor as collateral damage, plus a theoretical wiring loom issue caused by the current flow on earthed circuits

[Sesman]

TBH it’s a pretty quick job to split the solenoid and clean up the contacts. It’s probably a good investment in your time to avoid a potentially expensive collateral damage situation….just saying.

[Morala]

cheers lads a new solenoid it is then

[Sesman]

Are you sure you can’t fix the existing one? They come apart really easily. The problem is probably the copper contact bar in the solenoid, which is readily accessible and easily cleaned up. Assuming of course it’s an original relay/solenoid.

[Morala]

just an update on the solenoid problem, when i started to remove the solenoid i found one of the contact securing nuts was very loose could this be the problem, i have only got the bike so still learning the ins and outs of it cheers.

[McCabe-Thiele (Ted)]

I doubt it, if as you have stated the starter continued to crank over with the ignition off until the battery had run down, that could not be caused by a loose terminal.

[Morala]

no problem, will replace solenoid and again thanks for all the advice

[Sesman]

It could have created arcing on the solenoid contacts within the unit causing the copper contact bar to temporarily fuse to the contact posts. 110A starting current and IsquaredR would create considerable heat. I’m not convinced a new solenoid would be required. I’d suggest opening the solenoid to check the internal contact bar before spending your money. Your choice of course.

[McCabe-Thiele (Ted)]

Can the solenoids be unscrewed Phil or is it some sort of crimping, can't say I've ever taken one to bits ?

[Bryanj]

Bit of both on originals Ted

[Sesman]

My 1977 550 F2 original solenoid contacts canister and coil unit are joined together using two screws and a simple tongue and recess arrangement. I’ll try to get a picture tomorrow, as long as I don’t have to remove it to do so. Original units are very, very unsophisticated and all the better for it.

[Morala]

another update, i removed the solenoid and cleaned all the contacts, checked the wiring refitted the unit, will keep an eye on it over the winter cheers for all your help again.