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Bike Profile - Posted 11th June 2012

1977 BMW R80/7 - Part 13 - Not Starting, Unluckily
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It was all going so well, but now Martin Gelder's 980cc R80/7 airhead BMW won't turn over. Battery? Starter motor? Sandals?...

There's a Big Trip planned for Roxanne the 100,000 mile BMW R80/7 this summer, a trip which will involve some proper touring rather than just bopping about Britain. It's time for all the touring gear to be dusted off and bolted back into place.

Looking at the pile of grubby tubular steel and heavy duty plastic piled up prior to fitting, I worried about the added lightness I'd be removing, but the crashbars and pannier frames were surprisingly wieldy despite their apparent bulk; let's just hope the former are up to the job. Brush guards for the handlebars and the world's biggest mudflap for back wheel complete the set-up; all original BMW parts that no doubt added vastly to the bike's purchase price when it was new - thank you, original owner.

All from the BMW Accessories catalogue...

Then Mate o'Mine came down from Up North so that we could start to plan the Big Trip. We booked hotels, sketched out routes and argued about whose bike would be most suitable. I think in the end I won him over; what better bike could there be for any Big Trip than a slightly saggy BMW R80/100 made up from several different but similarly tired examples of the breed?

Pride, they say, comes before a fall.

Next morning I offer to ride some of the way back Up North with Mate o'Mine to further impress on him the suitability of Roxanne the Aged BMW. I wheel her out of the shed, pointing out the various touring accessories recently fitted. And the new sidestand spring.

Ignition on, petrol on, choke on, press the button, and... nothing. Flat battery, probably. Still, I'm sure Mate o'Mine appreciates that bump starting your friend's bike is excellent preparation for any Big Trip, and we were on the way in no time. With rain clouds looming I cut short my trip, heading for home after just 15 miles. Big Trips start with small steps, I say. Back in the shed, the BMW still won't turn over on the starter. There seems to be plenty of juice in the battery, the solenoid clanks away merrily, but the engine she will not spin.

I've had this before. In 1985, my R100S starter packed up while the bike was in the hold of an Isle of Man ferry. Have you ever tried bump starting a fully laden BMW, uphill, on a slippery boat deck, while half the motorcyclists in the world look on? The symptoms that time had been a starter motor getting more and more sluggish before it finally expired, and now I come to think of it, hadn't Roxanne been a bit hesitant to turn over when I left Mad Mike's gathering the weekend before? No matter, because back in 1985 a quick clean of brushes and commutator got the starter back in action for a further ten years. I'll have this fixed in a jiffy.

Only three bolts hold an airhead BMW starter motor in place. To get to these three bolts, however, you have to remove the petrol tank, the airfilter cover, the coils, the front engine cover, the top engine cover and the diode board / rectifier. The sight that greets me when I finally excavate my way in is somewhat archaeological. The starter is a cheery rust brown in colour and appears to have lain undisturbed for the full 35 years and 106,000 miles of Roxanne's tough life, No wonder it's turning over a little sluggishly.

Tony Robinson and Phil Harding just out of shot...

These old Bosh starters are completely rebuildable and come apart almost as easily as airhead BMWs. The brushes are short but within tolerance but the commutator grooves are filled with gunge. A bit of work with fine emery paper and contact leaner, some grease on the bushes, a wipe down with an oil rag and then it's just a matter of popping it back in, nipping up those three bolts, and then reassembling the rest of the bike around it before I take her for a spin.

Or not. The starter motor still won't turn the engine. I put the battery on charge, but after just a few minutes its "Fully Charged and Maintaining" light comes on. I put the kettle on. I ponder.

Some months earlier I'd sold the perfectly good, fully functioning start motor that had effortlessly cranked The Vicar's Bike into clattery action with boundless enthusiasm. I'd sold nearly all of The Vicar's Bike in fact, piece by piece, on . What I hadn't sold yet was the collection of random and mostly rusty spare parts that came with The Vicar's Bike. And I half remembered there being a Bosch starter motor in that pile somewhere.

The spare, Spanish made Bosch starter motor.

I found it. Eventually. It was much less rusty than Roxanne's original, although it claimed to be Spanish rather than German. Beggars can't be choosers, and into the bike it went. Eventually. After I'd removed the rusty German original. Again.

No, of course it didn't work. There are two reasons you would have a spare starter motor; 1) your current starter motor is about to expire and you have a acquired a spare in preparation for when it does, or 2) you have already replaced an expired starter motor with a shiny reconditioned one, and the "spare" you have kept is the old knackered one.

How many people do you know who buy a spare starter motor in advance of the current - fully functional - one packing in? Exactly.

It started to rain. I went inside to consult the internet oracle, in the shape of the RealClassic message board and various specialist BMW sites. Lots of good advice followed, most of it contradictory. I could buy a reconditioned Bosch starter. For a little more outlay, I could buy a brand new Valeo starter which might jam solid miles from anywhere, but probably wouldn't. And for even more money, I could buy a shiny Japanese starter motor more powerful than the engine which I was trying to start.

Or I could clean everything again, charge the battery again, test everything thoroughly again, and then if all else failed, I could see if a local auto-electrician could rebuild what needed rebuilding at a lower cost than a completely reconditioned start motor from a BMW specialist.

No special tools needed to strip Bosch starter motors.

Next morning, I set to cleaning and checking. I got the original German starter turning over using jump leads from Roxanne's battery, but it was very sluggish. It could barely turn itself over, to be honest.

I removed the Spanish starter motor and stripped and cleaned it. Its brushes were better than the German motor's, but it was grubby inside. More fine emery, more contact cleaner, and this time I deployed the final sanction; the cotton bud.

Hooked up to jump leads from Roxanne's battery, the Spanish Bosch now turned over quite briskly. It could almost be described as spinning.

And that was using poor old Roxanne's battery, which had now spent two days pumping current into knackered old Bosch starters. Probably due for a charge itself, then.

Big Trip BMWs on now

I cast around for an alternative source of electricity. Next door's solar panels wouldn't do; it was raining. The Morini has a perpetually flat 4AH jobby borrowed from a scooter eight years ago. No chance. The modern Yamaha has a tiny battery, no match for the needs of the car-sized starter in front of me. Car sized. Car. I've got a car! I've got a car with an absolutely huge battery, because it has electric powered steering, electric powered ABS, electric powered blummin' everything. It's got a battery the size of a small skip.

I connect the jump leads to the car's immense battery. I connect the negative lead to the Spanish Bosch starter. I tentatively touch the positive lead to the solenoid connections, and the starter - all five kilos of it - leaps out of my hands with a sudden burst of torque. Blimey. And ouch. Good job I wasn't wearing sandals.

Better charge Roxanne's battery then. And best check the acid levels before I do, just to be safe; it's an old style non-sealed lead acid job, with a clear case so that you can see the levels at a glance. Except I can't, because the case isn't really clear. I pop the first filler plug off, and add a tiny bit of distilled water. The next one needs a little more. The next one even more, and a worrying amount goes into the remaining cells. Where has all my acid gone? How could that happen?

Regular readers might remember this photo of the lengths needed to change the sidestand spring. The one I said might come back and bite me.

Seemed like a good idea at the time...

No petrol or oil was spilled in the process - I checked - but I had wondered why a small patch of grass appeared to be going a bit yellow.


Twelve hours of gentle charging later I'd refitted the Spanish starter motor and cleaned every electrical connection I could find, to give the current from the battery the best chance at getting to the starter. If this didn't work, I was potentially looking at a new battery as well as a new starter motor. Nothing to worry about there then.

Ignition on, petrol on, choke on, press the button, and...


That's good, by the way. That's what was meant to happen. That's the noise my BMW makes. But with more clatter as it warms up.

dubba-dubba-dubba-dubba-dubba-dubba-dubba. Ready for the big trip. Again...

So what have I learned?

  • Bosch starter motors can be home-serviced, but they weigh a tonne.
  • Don't wear sandals.
  • Just because a battery shows more than 12 volts, it might still be a little sickly.
  • Don't ignore the acid level on your lead acid battery.
  • Even if it's got a clear case that you can't see through.
  • Don't tip your bike on its side without checking *all* the fluid levels afterwards.
  • Don't ignore advice, however contradictory.

    Words and Photos: Martin Gelder


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