What the!.... Starter Motor

[ged in oz]

So, I was changed the oil and filter yesterday and adjusted valve clearances and did a few other little odd jobs before I headed off on a couple of hours excursion, (which got very wet) before finally loading up in town with heading home.

About 2 minutes after I headed out of town, (it’s a 30 minute ride home) there’s this incredible loud!, metallic clatter! Ohhhhh, well that was fun while it lasted, (was my first thought) and I pulled it over and shut it down on the side of the road. Having just changed the oil, I thought the worst and looked down expecting to find oil everywhere?, a huge hole in the crankcase?, a whole jug blown off, (like in the photo).... Nothing. Huh?

I thought well, it was still actually running as I pulled up, so I turned the key switch and it just started straight up! What?! Turned it straight off, then on again. Same result! The starter button was somehow jammed on.

It didn’t actually looked stuck in, but pressing it in and out a few times freeed it up and I was off again... Which was a much better result than the trailer trip home and the full rebuild scenario.

It had been raining, so it could have been a water short in the handlebar switch so I’ll pull the switch apart and treat it to some contact cleaner, but my question is has anyone experienced this before? I can’t imagine that’s done either the ring gear or starter pinion any favours.

[mrclubike]

What model and year  are we talking about and  is the wiring factory
Even if you push the starter button in it still should not crank unless you are in neutral or have the clutch pulled in

I would be looking under the starter cover at the smaller black wire going to the solenoid and making sure it is not shorting to the Bat Positive cable some how

[ged in oz]

It’s an ‘83 R65 and yeah, the wiring loom is mostly intact except for around the guauges and the rear end, which had all been modified previously. Most of the rest of the loom seems original, except the coils.

Yep, that’s a good suggestion to check the actual starter. I was in there a few weeks ago and cleaned and tightened a few bits and pieces and nothing untoward jumped out at me.

I’ve been putting a few more (dry) miles on it since it happened and it’s been trouble free so that’s good but I’d better get into that cover to have another look. Cheers.

[tunnelrider]

Even if you push the starter button in it still should not crank unless you are in neutral or have the clutch pulled in

Good point about those switches Mrclubike. I've had a stall sometimes at standstill, usually from forgetting to turn the fuel back on and had the most embarassing trouble getting back to neutral before I can hit the starter. Is it supposed to be either clutch in OR be in neutral to let the starter motor fire? My clutch switch was shorted well before I became custodian, so if you're able start the bike just by squeezing the clutch and not in neutral I'm gonna get it going like that again.

[ged in oz]

Hmm, another good point thanks guys.

My neutral light is constantly on, so I figured that the switch is buggered and needs replacing, but I hadn’t realised that there was another lockout in the circuit that is obviously either not working or has been bypassed.That’ll be worth checking as well.

[Tony Smith]

My neutral light is constantly on, so I figured that the switch is buggered and needs replacing, but I hadn’t realised that there was another lockout in the circuit that is obviously either not working or has been bypassed.That’ll be worth checking as well.

Neutral light on all the time means failed wiring harness diode. All R65 jungle saying.

You can make a replacement with a 10c diode from Jaycar and two crimp connectors - solder them however as crimping will not suffice.

Or you can spend $10 and buy the BMW part which will fail again in another 30 years :-)

[mrclubike]

Ged has a 83 so the Diode Tony is talking about is built into the starter relay
In order to repair it with the cheap diode you have to  change some wires at the relay

[ged in oz]

Well, there you go.... That’s a really complex way to idiot proof the starter button isn’t it! I hadn’t even noticed the interlock switch at the clutch perch, but it gives me a few places to start searching. I’ll have a bag full of 1N4001’s stashed away somewhere.

I’ve been looking at the wiring schematic and trying to get my head around that diode! I’ve done a bit of circuit theory over the years, but I’m still scratching my head a little trying to understand how that circuit is working. Anyway, I’ll pop the tank and the top cover tomorrow and have a little poke around. Thanks heaps for your help guys.

[ged in oz]

What model and year  are we talking about and  is the wiring factory
Even if you push the starter button in it still should not crank unless you are in neutral or have the clutch pulled in

I would be looking under the starter cover at the smaller black wire going to the solenoid and making sure it is not shorting to the Bat Positive cable some how

Thanks for those tips Mrclubike.

I posted in my resto thread the other day about getting a dirty big spike in my rear tyre and flattening it but simulataneously! I got the hideous grunching noises again!

I pulled up and turned it off, then started it up again. Same noise, but the motor wasn’t starting on the turning of the key switch this time. I had to actually hit the button to engage the starter, but same noise. I’m thinking gearbox or clutch this time.... The starter thing didn’t occur to me.

The tyre is flat anyway, so I rang and arranged transport home and then I started it up again to try and diagnose what has let go, and the noise is gone....

It has to be the same noise!  The starter motor just engaging itself randomly and/or not releasing on startup.

So, my Neutral light is constantly on as well which has led me to finally pull the tank and have a good look at what’s going on.

The neutral switch has been jumpered to bypass it and the clutch lever switch came to pieces in my hand as well, so I assume that is NS too.

By my understanding of that circuit, if the neutral switch dies and the clutch switch is also dead, you cant engage the starter relay? That would explain the jumper on the neutral switch leads and the neutral light being on all of the time.

But, what would happen if the starter relay also starts shorting itself or breaking down and therefore engaging randomly?

I know that the theory relies on the clutch switch being broken, the neutral switch being broken and the relay also being broken!, so long odds, but still...

[mrclubike]

Here is the start power circuit thru the relay
Yes if the start relay is broken inside it could be closing randomly

[mrclubike]

Here is the starter button circuit to the relay coil B+

If the starter button is closing the starter will crank

[mrclubike]

Here is Battery NEG circuit thru the clutch switch to the coil in the starter relay
 
It is in parallel with the Neutral safety switch circuit that can also supply battery neg to the coil in the starter relay 

The 2 circuits are separated by a Diode to keep the neutral light from coming on when the clutch is pulled in

This diode is inside the relay on later bikes and outside of the relay on the earlier bikes

[mrclubike]

Here is is the Battery NEG for the start relay coil thru the Neutral switch

[mrclubike]

Here is a close up of the relay
The diode is inside

A standard relay can be used if   add the diode to the the neutral  circuit

[tunnelrider]

Nice clear diagrams Mrclubike, thanks