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Bike Profile - Posted 5th November 2010

BMW K75RT Part 1
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Steve MacGregor wanted a semi-serious touring motorcycle and BMW's three-cylinder 750 seemed to fit the bill. We join him on his initial long ride home…...

The touring bug had bitten during a European trip on a Honda XL 500 (and you'll be able to read all about that adventure in the November 2010 issue of RC magazine). I wanted to go to the Continent again, but a little faster and in more comfort than the Honda provided.

I needed a bike that was comfortable and reliable and that had a fairing and hard luggage. Performance and top speed weren't important, but it had to be capable of sustained cruising at 75mph. Oh, and I didn't want to spend more than £750. An early short list included the Yamaha FJ1100/1200, GTS1000 Kawasaki and a K series BMW. The more research I did, the more I liked the look of the BMW.

The K bikes were launched in 1983 with the four cylinder 1000cc K100. This was followed in 1985 by the three cylinder 750cc K75. Both models share a number of common parts and both have water cooled, fuel injected engines mounted longitudinally in the frame and laid flat, with the crankshaft on the right and the cylinder heads on the left. A stainless steel exhaust comes as standard and the bikes feature Monolever rear suspension - a single-sided swinging arm incorporating the drive shaft and suspended from a single shock absorber. Both models came in naked, 'RS' (half fairing) and 'RT' (full touring fairing) styles.

These bikes have a great reputation for reliability and longevity, though the K100 is reputed to suffer from unpleasant high frequency vibration (a friend who owned one constantly complained about 'white finger'). The K75 is fitted with a counterweight and so is much smoother. I also happen to like 750cc bikes - they aren't so small that you have to rev them constantly nor so large that you spend most of the time looking at a two-thirds unused rev-counter. I also wanted a decent fairing, so that'll be a K75RT then.

Unfortunately the RT was manufactured only from 1990 - 1995 (all K75 production ended in 1996), so there aren't that many of them around. The situation is even worse here in the Highlands of Scotland where the choice of used bikes is very limited. Fortunately early K bikes are currently deeply unfashionable, so they are generally cheap when they do turn up.

Many police forces used the K75, so a number of second hand bikes are ex-police models. I had rather ambiguous feelings about buying one of these. Whilst owned by the police these bikes are well maintained. However, when sold on they are often bought by impecunious riders who skimp on maintenance.

Be afraid. Be very afraid… BMW K75RT

After some weeks of searching I found a K75RT advertised for sale about 100 miles away. A quick phone call revealed that it was white and yes, it had a single seat. An ex-police bike then. Next day I went to have a look. The bike had 53,000 miles on the clock and was equipped with thin police panniers - wide enough for a tazer and a sandwich, but not much more. To compensate, a topbox the size of a small camper van was fixed to a slab of rusty iron at the back of the bike. The topbox was so wide that the pannier lids couldn't be opened without removing it first.

The whole bike had a light patina of corrosion and neglect. The top and bottom sections of the fairing were cracked where the bike had fallen off the stand and paint was flaking off the sidepanels and front mudguard. The idle was ragged. On a short test ride I found that the front brake was almost completely ineffective and I could hear the unmistakable sound of unsynchronised fuel injectors as it wheezed up through the revs. But the engine was oil tight, the clutch and gears were fine and the bike did have a current MOT and tax.

Fat topbox. Thin panniers. Never a good look.… BMW K75RT
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The sensible option would probably have been to leave it. But you know how it is; even a dodgy bike is better than no bike. So, I made what I thought was a derisory opening offer. To my surprise, the seller accepted with alacrity.

I returned next day to collect the bike. By the time I was ready to leave, the sky had darkened and the first, fat drops of rain were plopping on to my visor. By the time I had filled up with petrol and checked the tyre pressures, the monsoon had started.

It quickly became apparent that something wasn't right. The bike followed joints, seams and markings on the road like a misguided cruise missile. I crossed a tarmac seam while overtaking a bus and the back wheel made a spirited attempt to overtake the front. I wobbled into a layby to allow the palpitations to subside and checked the head, swinging arm and wheel bearings. All were fine.

Single seat, flaky paint… BMW K75RT

The suspension also seemed good and the Metzler tyres had plenty of tread. I set off again, very carefully. At any speed the bike felt insecure and nervous. Over fifty it felt downright frightening, weaving without warning. I puckered up and carried on slowly. After what seemed an interminable 100 miles, I arrived home and threw the bike into the shed in disgust. I tried to field the inevitable 'what's it like?' questions from my wife.

Next evening, I took it out again, this time in the dry. It was slightly better, but it still felt completely insecure when crossing any sort of irregularity on the road. I did some research but failed to unearth any clues except for one K100 owner who said that he was ready to get rid of his bike until he replaced the Metzler tyres. Hmm. A quick root about in the shed unearthed a pair of part-worn Bridgestone BT45s of the right sizes. Fitting tubeless tyres yourself isn't difficult - you just need long tyre levers, teflon knuckles and a comprehensive vocabulary of swearwords.

If you look really closely, you can actually see it weaving… BMW K75RT

I tried the bike with the Bridgestones fitted. What a transformation! It felt planted and secure. I really couldn't believe the difference. I can't explain this - I have used Metzler tyres in the past without any problems. The tyres I took off were worn, but well above the legal limit and they weren't perished or warped. I can only assume that there was some kind of mismatch between tyres and bike, but I haven't come across anything this severe in 35 years!

What a relief! I was starting to think I'd bought a complete turkey. Right, now it's time to think about getting rid of that single seat. And that topbox. And those fuel injectors need looking at…


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