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Bike Profile - Posted 22nd July 2011

1977 BMW R80/7 - 1000 Miles on 1000 Barrels - Part 11
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It's been more than 1000 miles since Martin Gelder jammed a set of R100 barrels and pistons onto his innocent BMW R80/7. Time to ride to Wales and back to see what breaks or falls off...

At the end of my last epistle, I wondered how long the clutch would last after I had fitted 1000cc barrels to my 1977 BMW R80/7.

I can now reveal that the answer was "not long".

The first 500 miles on the new barrels had been covered at less than 4,000rpm, an easy enough task on a bike which will pull from tick-over and then approach the legal speed limit at my self-imposed maximum revs. As I began to run the bike at higher revs two things became obvious; firstly that it was more vibratory than before the conversion, and secondly that it now pulled much more vigourously. So vigourously, in fact, that if given full-throttle suddenly, the clutch would lose its grip on the situation.

The vibration became apparent on the bike's first long dual carriageway run, to the Clubs Show at Stanford Hall. It's 70 miles door to door, most of them on the poor-man's motorway that is the A14. At 65mph, the BMW had been smoothly wonderful. At 70mph on that first A14 run, it was buzzing like an angry wasp trapped in an upturned paper cup. Coming home it didn't seem so bad, and the vibration didn't get worse with speed. Drop below 68mph and all was sweetness and light; above that and the handlebars tingled in a way they hadn't when the bike was an 800.

A couple of weeks - and a further few hundred miles - later I was back on the A14, coming home from Mad Mike's Leicestershire Gathering. The vibrations had now moved slightly up the rev range - 75 mph, rather than 70mph, and were less noticeable through the bars than through the footpegs. I'd checked the carb balance, checked the timing, checked the tappets, changed the oil, checked the engine mounts... Perhaps this was just the bike still settling down?

Grey tankcover makes the bike look clean. It isn't. 1977 BMW R80/7

Away from the monotony of the A14, on ordinary and slightly slower roads, the bike remained a joy to ride. Since the conversion it's become much more... stable. Not stable in the handling sense - this is a 1970s Boxer BMW we're talking about - but stable in terms of its usability. It stays in tune longer - much longer - now that the valves aren't recessing into the head, and there's no sign of any pinking or other poor combustion. It starts reliably all the time, rather than only after being fettled, it doesn't burn oil, it only smokes after it's been left overnight on the sidestand, and it's stopped leaking oil. Before I replaced the pushrod tube oil seals I'd assumed that much of the oil coating the lower half of the crankcases was coming from an oozing sump gasket, but it now appears that all of it was coming from the pushrod seals.

None of these improvements are due to the switch from 800cc to 1000cc; they're simply the result of replacing some very worn components with either new or slightly less worn components. They've had a real effect though; the BMW can now be relied upon. I hadn't realised how finicky it had become, but it's been my main two-wheeled transport since Easter.

There was a bit of a BMW hiatus during July, while I got the Morini MOTed and then ready for the Festival of 1000 Bikes. So it was a real surprise to fire up the BMW again and realise how... civilised it was in comparison to the Morini. So smooth, so refined, so comfortable, so squashy. Yes, it tingles a bit on the motorway, but it's an oasis of calm compared to the Morini at the same speeds. And the BMW is now properly grunty, like a big twin should be. Clutch permitting. Ahem.

The Midway Truck Stop; Still going Scene of many a big breakfast - although not a Big Breakfast - in my past

In an ideal world, I'd have replaced the clutch before setting off on the 500 mile round trip to the Compass Challenge in Wales. I've already got a spare gearbox, shaft and bevel box ready to go on, and I even got as far as buying a new clutch plate and the various necessary stretch bolts from the ever-helpful Motorworks, but life got in the way of my plans and so on Tuesday I found myself once again heading West along the A14.

In normal use the clutch was fine, and kept to the sweet-spot just below the tingle-zone the bike cruised happily onwards to the M6 and then M54. I was less happy, but that's my own fault for fitting "LT" bars that are supremely comfortable at bimbling speeds but leave me feeling somewhat spinnaker- like after sustained motorway cruising. Perfect for the A41, mind, which led me through some happy memories of riding that road thirty years ago. I grew up on the Wirral, where my parents still live, and every interesting bike journey in those days seemed to involve the A41 at some point.

Scene of many a misspent youth The Dee Estuary, Hilbre island, and beyond it the sea. As far West as I could go.

The run into Wales to the Pondersoa Cafe on the Horseshoe Pass on Wednesday was equally nostalgic, once I got clear of the new roads around Queensferry and Buckley. While stopped to take advantage of some photogenically presented hills a pair of bikes passed me, then another pair. Could they also be heading to the Ponderosa?

All sorts of oddities turned up Scene of more big breakfasts in my past
BMW R80s on Right Now......

Indeed they were, along with many others. Breakfasts were consumed, coach parties entertained ("I had a Triumph T100 when I left the army, but it was nothing like this one" said one chap, pointing at a Hinckley Bonneville) and then we were off to what must be the most charming motor museum in Wales, if not the whole of the British Isles.

Pleasantly chaotic

And then it was time to head home. Choosing the A5 was a mistake and I soon decided to follow the front wheel rather than my prepared directions. The BMW had coped admirably with busy motorways, empty A roads and twisting Welsh B roads but was less happy with the cut and thrust of mid-day, mid-week, middle-England traffic. As the miles mounted, the clutch started to become less predictable, sometimes grabbing, sometimes dragging, and the gearbox became less cooperative. My mind started adding its own clattering to the noise of tappets whenever I stopped, and I was happy to arrive home.

So what next?

As soon as this story goes up on the website I'll be crowbarring off the old gearbox and shaft, hammering in a new clutch plate and a holding it in place with a complete lower mileage transmission. If all goes well, it'll be finished in time for me to get to the Sibbertoft Shuffle on Saturday afternoon. We shall see.

And while I'm at it, I'm going to have a go at rebalancing the carbs to see if I can ease the vibrations. I suspect, though, that the vibes are at least partly due to a change in balance factor between the different generations of engine that I've mashed into one lump, with crankshaft and conrods from an earlier bike, pistons and barrels from a later one.

Words and Photos: Martin Gelder


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