solenoid sticking

Well, finally kicked my Mk3 in the guts after a two yr full rebuild from a basket case.
Just prior to kicking it over the kickstart spline decided it had had enough so I was left with the electric leg only. Not the ideal way to start a new bike I thought, but hit the button anyway. Holy s..... it leapt into life! I invested in a Comeau starter, a new solenoid from Nick at Andover, made up huge cables and fitted an Odissey(sp?) battery. The re-built engine is very tight but you only have to look sideways at the button and it starts.
On the third start the starter did not shut off when I took my thumb off the button, so I had the engine running and the starter still turning !! I turned the ign off and it was still running while I was frantically trying to get the sidecover off to disconnect the battery. Needless to say it ran the battery down before I could achieve anything. I was standing there (pale and shaking) thinking of melted (expensive) starters, wrecked (expensive) sprags and ruined (expensive) batteries, looking for a cat to kick! The starter and battery were red hot. No voltage reading on the battery at all, so I thought it might not take a charge.
Took the battery back to the supplier to try their big fancy charger - no worries! Put it in the bike, connected up except for the starter cable, pressed the cable onto the terminal, pressed the button, vrrrm!
Apparently no damage! Tried a couple more times - OK, then it stuck again. just took the cable end off the terminal - OK. It stuck three out of eight starts, but when you test it on the bench it works fine every time.
My question is - has anyone else had trouble with the solenoids from Andover? Nick is sending me another but I will always be nervous now waiting for disaster! He tells me they source them from a third party and you cannot get Prestolite ones. Anyone know of other sources? Do outboards use the same ones?

shedweller said:

Anyone know of other sources? Do outboards use the same ones?

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I think that maybe you were just unlucky and the solenoid was faulty?
Just about any automotive or marine starter solenoid should work although you would need a type with an output terminal for the ballast resistor bypass circuit if you are using points ignition, but you don't need that for electronic ignition systems.

Somebody(?) here replaced their original solenoid a while ago with one bought from an auto shop, as even the Prestolite type have been known to be troublesome.

A bit over ten years ago, a former Norton dealer told me it was the same solenoid that was used on some Ford vehicles back in the day. I took it to the local NAPA and got one that appeared to be identical for $17 (1997 prices). It's still going strong. I have to admit I was a little shocked at what stockists get for the original now. It's not as bad as the Bosch solenoid I just put on a 1983 R80RT BMW. It was about $140 from the BMW dealer, though I found it (after the fact) from a Bosch stockist for $37.

Hi shedweller, I have had the same problem last year when I rebuilt my Norton. I have a Dave Coneau starter and had a new "Andover Norton" solenoid, but at that time a lead acid battery.

The problem righted itself on my Norton, but unfortuneatly I don't think that I can shed any definitive reason as to why this happened, but I have been there with the hot flat battery and hot starter.............scary! Luckily the battery on mine flattened quite quickly.

As I said, I had a lead acid battery at the time, which came with the bike when I bought it. I wondered if this was faulty and not giving enough voltage/amps to "engage" the solenoid properly, as the solenoid when it malfunctioned seemed to "chatter."

So I bought a glass matt battery, and since then, no more problems, and I use the electric leg 90% of the time. I realise that my potential theory is not based on any sound electrical knowledge, but it is a fact that since I fitted this battery, it has never occured again. I assume the battery that you were using was new and fully charged?

Are there any sparkys that can make sense of this, or is it just fluke?

Reggie said:

As I said, I had a lead acid battery at the time, which came with the bike when I bought it. I wondered if this was faulty and not giving enough voltage/amps to "engage" the solenoid properly, as the solenoid when it malfunctioned seemed to "chatter."

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Yes, I have heard of this before, and I thought that this was a common problem with the Prestolite solenoids?
If the battery is faulty or discharged then the electrical drain from the starter motor turning over causes the system voltage to drop to a point where the solenoid isn't getting enough power to keep the contacts closed.
The contacts open and the voltage increases (because the starter has become isolated) so the solenoid will again close the contact points momentarily, the whole process is then repeated quite rapidly, this being the 'chatter' noise heard.
This rapid make & break of the solenoid contacts apparently causes them to overheat as sparks can be generated between them each time it happens, -a bit like striking an arc when stick welding, so the contacts can burn and fuse themselves together, resulting in a starter motor that won't stop turning!.

I think that an uprated starter motor would actually increase the amount of voltage drain? So I could see this making the solenoid problem worse if a standard battery was then used? And a bad starter wire or Earth/Ground return wire connection could cause it too, so I would ensure all the wire connection points are cleaned to bare metal and that the return wire is fixed down to the crankcase at the stud immediately below and to the rear of the barrels on the left-hand side, and not connected to the engine cradle.

That makes sense. :idea:

L.A.B. wrote;

This rapid make & break of the solenoid contacts apparently causes them to overheat as sparks can be generated between them each time it happens, -a bit like striking an arc when stick welding, so the contacts can burn and fuse themselves together, resulting in a starter motor that won't stop turning!

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The problem that I was having was as stated above, and as you explain, once the "chattering" had started I couldn't stop it even though the starter button wasn't being pressed any longer. This happened to me seven or eight times in total, luckily there seems to have been no permanent damage to my solenoid

Thanks for the replies, gents. There didn't seem to be any chattering. It just sticks on. As you suggest Les I should take a dedicated earth from one of the sol mounting bolts - maybe even to the battery terminal seeing it is so close. I have been pretty careful to ensure everything is earthed properly but not the solenoid.

My comments were really concerning the soundness of the heavy starter wire connections, but I'm glad that you've raised this point about the solenoid trigger circuit electrical connections, as I expect those also have a bearing on how the solenoid actually performs during starter operation due to the voltage drop.
The original Prestolite solenoid should theoretically have a return path to the battery as it mounts directly to the frame, but a dedicated solenoid Earth wire would certainly be a good idea, although there should be a solenoid red return wire within the Mk3 wiring harness with a ring terminal that can be fitted directly to one of the solenoid mounting bolts? I presume that the new solenoid is the same Earthed mounting connection type as the original?

I had my harness made up by Bruce Carrad in NZ. There was a ring terminal earth just there but I did,t realise it was mesnt to go on the solenoid. I bolted it to the frame just below there. I will take a short earth from the solenoid and join it there.