Matz Rosenquist's Special Bike Story

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HPN G/S1000 - frame #3
The story about a very specialized Motobike

by Matz Rosenquist, Sweden
HTML Conversion V1.0.3 (25-Dec-96) done by Claus Possberg, Germany (HPN frame #6)


As most of you BMW-owners know, BMW won the "Rallye Paris - Dakar" four times in the 1980's. This was done with help from the firm "HPN Motorradtechnik" in Seibersdorf, Germany, who developed the bikes on BMW's behalf. Most of you have probably seen pictures of the bike in its right element, i.e. the Sahara desert.
The first time I saw a photo of the BMW's, I thought this tall and strangelooking bike with its huge fueltank in front, not to mention the enormous frontfork and a large twin propelling the whole thing, must be made for people from another planet!! But still, it was ridden by a tiny Frenchman, Gaston Rahier, just 5 ft tall!

After the last victory, HPN built 10 replicas of the bike to be sold to the public. It's intended use, of course, was to race the "Rallye Paris - Dakar", and BMW was to sponsor with a large sum of DM's. In all, 35.000 DM's would be handed over to the winner of the amateurclass. One of the replicas made it's way to Sweden, bought by the owner of the Swedish BMW importer at the time, Mr Bo Rindar. A large article in the Swedish magazine "Superbike" in 1987, presented the bike with nice pictures. As soon as I saw the centerfold picture, I was impressed with the looks of the bike and the "aura" surrounding it. Somehow it etched itself into my mind and I just couldn't forget about it.
Well, as times goes by, things do tend to slip away, and even the etchings in my mind started to fade. I had almost forgotten about it, until a few years ago, when I met Bo, now the ex-importer but still the owner of number 3. We talked about his HPN, I even asked if he would consider selling it to me, but "Noway, I'll never sell that bike"!! I asked him to think of me "if" and "when" and "maybe" he was to let go of the bike. He agreed, but said that it would never happen anyway, so I shouldn't really bother. At the time I was well into BMW-ownership, having a '85 BMW R80 G/S Paris-Dakar, along with a '90 4-valve K100 RS in the garage.
That could have been end of story, but when I met him one and a half years later, he was actually considering selling the bike. The bike might be for sale! But he wanted to think it over once more, and promised me an answer as soon as he came back from testing new Honda's in Spain. The answer was "Yes, it's for sale and I would like you to be the new owner!!" My main concern was how to be able to buy it. I loved my pearlywhite K100 RS, and I had been to Africa on my R80 G/S, too many memories involved.
It was actually very simple: they both had to go! Said and done, off they went, and on the 1'st of April in 1995, I became the owner of the only HPN G/S 1000 in Sweden. Suppose I don't have to add "proud". And I can still remember my neighbours wife telling me "that funnylooking bike is much TOO big for you". I still can't understand how she dared! And I was so proud of my new toy!


I bought the bike unseen and undriven, so it was with excitement I fired it up for the first time. As soon as I heard the song coming out from the race-exhaustsystem, it was worth every cent and more! Just lovely! Riding down the street and back turned into a big disappointment though. The bike felt very heavy, very uncomfortable and it was HUGE. And it was absolutely impossible to turn. It was with very mixed feelings I closed the door to my garage and I must admit that I felt let down by my own expectations. Rats, I should have kept my old R80 G/S and that lovely K100RS!!! But as another saying goes: things get better with time. Today, I wouldn't even consider selling it, not even for a brand new yellow, chequered painted K1200 RS equipped with all the accessories imaginable.

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The faithful old BMW R80 G/S

The life of an HPN G/S 1000 starts with a R80 G/S. The original G/S was introduced in 1981, and was the first of the now so popular large offered bikes. It became trendsetter towards a more allround type of motorcycles. It was equipped with this strange onelegged rear swingarm and a 33-litertank was introduced on the Paris-Dakar version in 1985. It very soon became THE bike for "from-far-away"-travellers. In Germany, it was almost instantly nicknamed "Gummikuh", or "Rubbercow" in English, because of the soft frame (and and mainly from the up and down movement of the rear suspension - note from Possi). Heavily loaded, it happily flexed its way along the road. Anyhow, this turned out to be a good base for a real desert-racer. The modifications needed to make the basic R80 G/S competitive are extensive. For the real technical freak, here comes a list with modifications done. The not-so-tech-freaks, please look further down.

Starting at the front, the standard front fork has been replaced by a 42 mm Marzocchi M1 Paris-Dakar unit with 280 or 300 mm travel. It is not of the modern cartridgetype, which means that adjusting the front suspension is down to fiddling with oils and springs. The frontbrake has been replaced by a Brembo castironrotor and with a 4-pistoncaliper. My bike was originally equipped with an aluminiumrotor which was replaced as it had a habit of cracking. A stainlessteelbraided pipe is used, of course. Also, a highmounted fender is carried below the lower tripleclamp. This worked more or less as a sail, making the bike difficult to ride in strong sidewind. I've mounted a modified fender from a Honda NX 650 Dominator, had it sprayed in white and Marlboro-red and it looks great. A couple of clamps had to be made to attach the fender to the lower forklegs. Works fine, most of the windsensitivity is gone. Instrumentation is R80 G/S, and I have added an optional revcounter. The headlight is replaced by a round K100-unit and an airshroud has been added together with a tiny windshield, also taken from a K100, for windprotection.

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Reinforcements


One weak part of the frame is the area around the steeringhead. This has been taken care of by adding reinforcements leading from the central tube behind the steeringhead, up towards the upper part of the steeringhead. The reinforcements leading down from the lower part of the steeinghead along the two frametubes in front of the engine, are replaced by thicker and larger plates. Another weak part is the mountingpoint for the rear swingarm. Here, large plates are welded to the frame for strength.
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Reinforcement

This is very important, as the original singlelegged and single shocked rear swing is modified, and very much so. Firstly, the swing is cut in two pieces, a steeltube is welded into place, adding 100 mm to the length of the swingarm. A second leg is added on the left handside, giving the bike a very strange look from behind as the added leg is angled outwards at the rear, making it possible to remove the rear wheel. In front of the wheel, a large boxsection reinforcement has been added between the two swingarms. And while they were at it, another shockabsorber was added. Need I say that the mounting points for the shocks has been relocated and modified. The swingarm is now controlled by two White Power units, adjustable for rideheight and rebound and with a travel of 238 mm. The rearframe is strengthened and modified, adding mounting points for the rear fueltank. On one of the tubes of the subframe, the original airpump is fitted on a couple of pegs! The bike has got three fueltanks! One up front, one below and one behind the seat. The front tank holds about 45 litres, the middle 6 litres and the rear 9 litres. In all, it carries 60 litres of fuel, giving it range of around 1000 km's!! The front tank is made of nylon, paintable as fuelfumes does not dissipate through the material. This is the only tank I normally use, as the rear tank is painted but not made of nylon, alas fuel inside = no paint on the outside. The middle tank, I don't use as the seat must be removed for access, and besides, I want the bike to have as much weight on the frontwheel as possible. The seat is a standard R80 G/S dualseat, cut in half, reupholstered and covered with suede. I've replaced the R80 G/S handlebar for a Renthal albar, not as wide and a little higher for comfort, and a couple of handprotectors are added to the handlebar
My bike has got the standard R100 RS engine, giving slightly more than 70 Hp's (I think). No real racemodifications has been done to it. The typical output from these engines are 67 Hp's, but I suppose mine is putting out a little more as it is equipped with the competition exhaustsystem and the square airfilter box has been replaced by the older round version, with a modified housing, giving better airflow. A different quickfit type of airfilter is available from HPN, but not fitted to this engine. The exhaustnoise has been reduced somewhat by fitting a couple of silencerinserts from a Yamaha TT600. To make it streetlegal, the standard R100 RS exhaustsystem is normally fitted. Remember, the bike is intended for long enduranceraces, so high power output is not the issue. The engine can be ordered with a set of cylinders, giving a displacement of 1043 cc's and making the engine about 1" narrower. Unfortunately, my bike was not ordered with this set, it simply was too expensive. Would have been nice though. The standard 40 mm BING carbs will be replaced this winter by two 40 mm Dell'Orto's equipped with pumps. Hopefully, a great difference. An aluminiumring has been added to the sump, increasing the oilcapacity with one litre. A duraluminium skidplate now acts as the bottom of the sump. The RS oilcooler is located between the frametubes in front of the engine. The old oiltubes were getting soft and has been replaced by steelbraided ones. The engine is not fitted with an oilthermostat. The standard RS-thermostat can't be used as there is no room for it between engine and frame. HPN has developed a thermostat, which I will add in due time. The normally "square" valve covers fitted have been replaced by the older, rounder type, just for looks. I have modified them for easier removal by drilling holes in the covers, adding Helicoilinserts in the cylinderheads, using stainless steel Allenscrews from the outside to tighten the covers. Looks professional and is very neat. The gearbox is a standard unit from the R80 G/S, stripped and blueprinted There are different ratios available for first and fifth gear, but not fitted to my bike as far as I know. It feels very tight, and is not easy to operate. Shifting gears must be done very smoothly, yet firm and distinct. It is actually a real "crashbox". I am currently using BelRay GL-5 oil which makes the box is a little easier to use. HPN offers an extra oilpump for real "heavy duty use". My bike does not have this option installed. The final drive has been changed to a R100 RS finaldrive as standard ratio is far too low for the way I use the bike.


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Michelin T66
The rims front and rear are 1,85 x 21" resp. 2,75 x 17" and the spokes are more like a fore-finger in thickness. The front wheel has got the optional and stronger Brembo hub. The front tyresize is a conventional 90/90 x 21", and the rear is a "fat" 140/90 x 17". The rear wheelhub is a standard, drumbrake and all, slightly modified to accommodate the rim with its thick spokes. The rear brake is normally actuated by a rod, but has been converted to a wire, and the lever at the finaldrive is modified in such a way that it points upwards. This is done only to avoid possible damage. At the moment, I'm using Michelin T66's front and rear. A good tyre, wears well, is goodhandling and has good grip on both wet and dry tarmac. As I don't use it offroad (I use a HONDA XR250 R for that), I can't tell about the characteristics on loose surface.

Crashbars are delivered with the bike, but does not come with the sidestandtype on the left side. Suppose the bike is too high. I have chosen not to add the crashbars, the looks again. The centerstand had to make way for a different version, which is harder to operate. All plastics are made by Acerbis, highquality and good fit. Turnsignals and rear-view-mirrors are fitted to make it streetlegal. There was no brakelightswitch for the footbrake. I added one, neatly tucked away into the part of the frame that carries the exhaustsystem. A toolbag is fitted to a large piece of leatherbacked Velcro, screwed into nuts moulded in the front fueltank, and an expandable box is mounted on top of the rear fueltank. Both cases are made from thick, black leather. With all this information, I bet you think, "It's got to be a heavy beast! "But the fact is that its weight is below 200 kg's empty! Fully loaded with all tanks filled, it comes to around 245 kg's.


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HPN frame #3


When I took delivery of the bike, I had difficulties getting used to its behaviour. I have since then learned, that it oversteered badly. For starters, the frontfork didn't work very well. It was too "sticky", the forklegs did not slide easily enough. I started to laborate on forkoils, ending up with Spectro 5 with standard volume. At the rear, I adjusted the sag to a rule-of-thumb-setting. Sitting on the bike in riding-gear, there should be 1/3 of negative travel and 2/3 of positive travel. The whole thing started to behave, not good, but acceptable.
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HPN frame #3

I then discovered the real problem: one of the shockabsorbers was leaking and had probably lost its gaspressure, The pair was rebuilt last winter and as a result the rear sag had to be readjusted. At the same time, I took the frontfork apart, polished the innertubes and the inside of the outertubes to make them slide smoothly. After that I was back to square one again. I had managed to make he front and rear suspension work as a pair with the defect shockabsorbers, and then, when one end was corrected, it just didn't work together with the other. After getting in contact with Mr Pepperl (the "P" in HPN), I learned that a viscosity of 13,5 was the weight of forkoil to use. This can't be found, but adding equal amounts of 5 and 20-oils gives you SAE 13,5! And this worked miracles! It still is a bit stiff with the front fueltank almost empty, but I can live with that.

When starting the bike cold, sometimes there was blue smoke coming out, mainly from the left side. While doing some work on it last winter, I discovered there was a "puddle" of oil in the intakemanifold. I was a bit confused as oilconsumption was virtually nil. I suspected the reedvalve controlling the crankcasepressure to be faulty but it was in good order. To avoid this, I rearranged the breathertube from the reedvalve to exit in an K&N crankcasefilter mounted on a bracket attached to a crossmember behind the gearbox. And the blue smoke was gone. Another problem I still have is the gearboxinputshaftseal (nice long word!). The seal was replaced last winter as it had developed a leak. And the new one is also leaking! And something else; the oillevel in the swingarm increases, while the level in the gearbox decreases. It seems as pressure builds up in the gearbox, pressing the oil out through the seals. The ventilation is done via the screw securing the speedometercable to the gearbox, but nothing is wrong there. It's not a big deal, but I don't like motorbikes leaking oil. As long as it is not a British bike of course, but that's a different story!

I think that's about all on the technical side. When I became the owner of HPN frame #3, it had about 20.000 km's on it. I have covered something like 15.000, adding up to about 35.000 km's.
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HPN frame #6

The frame is painted Marlboro red along with the rear tank, airshroud and the front part of the frontfender. The rear fender is white, so is the rear part of the frontfender. The front tank is also white, decorated with the three BMW-colours in a wide ribbon across the tank from left to right. The HPN logo is present on the airshroud and on the front and rear tanks. A bit too many in my mind, but that's the way it looked and the paintjob is excellent. Now, how is the bike to ride? As I mentioned earlier, it is HUGE. I'm only 1m73 tall, about 5ft 9, and I have difficulties in reaching the ground when standing still. But once I get the thing going, it feels secure and very stable. For those of you who are familiar with the R80 G/S, the difference is vast. The frame feels steady as massive steel, no twisting or flexing whatsoever. Riding in a straight line is extremely easy as the trail is large. Turning the bike into a corner takes a bit of planning as the chassis is very "slow" in its reactions. Bare in mind, the bike is intended for use on very loose gravel and sand, and it would virtually kill the rider if it had a nervous character, hence the "slow" feeling of the chassis. I wanted a faster responding chassis, so I raised the forks about 3 cm's in the tripleclamps, reducing the trail a bit.
This is a summary of how I find the characteristics of my HPN once I got the suspension working: it is "slow", the long suspension travel must be taken into account, the height of the bike doesn't bother me anymore, the characteristics changes with the fuelload, it feels very tight, it is very predictable and very fun to push really hard, and I mean HARD. The big engine with its large amount of torque is magnificent and the harder you drive, the better it sounds!!
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HPN frame #5

Top speed is about 200 km/ hour, I don't really know, but I have seen 195 on the clock and there were a lot more coming. Via Internet, I have been lucky to find two of the remaining nine bikes. Number 100005 is located in London, owned by Mr Peter Young, the other is owned by Mr Claus Possberg in Germany, whos got HPN frame#6.As far as I know, those two bikes have got the full 1043cc engines. A few years back, I visited the BMW Museum in Munich, and as I recall, there was another on display,but I'm not quite sure. If that's the case, I've managed to locate four of the ten bikes, I wonder where the rest can be found? According to Mr Possberg (who's got a lot of information about his journeys available on the Internet, nice pictures and stories), HPN has a list of the original owners of the first ten bikes.

A small piece of interest. HPN frame #3 might have been the bike on display at the IFMA exhibition in 1986. Along with the bike, I got a complete set of documentation, and there is an indication that this can be that very bike.

This is all I know about my HPN. I can't guarantee that everything is correct, and if there is anyone out there who knows better or more on this subject, feel free to comment and I would welcome any information.

Most of this information is compiled from documents that came along with the motorbike. Pictures have been copied from different sources on the Internet, except for the ones on HPN frame#3, which are my own. The photo of HPN frame#5 was sent to me by Mr Peter Young, and the reinforcements have been scanned from the 95/96 WÜDO-catalogue.



Author: Matz Rosenquist, Gothenburg
Address: Fussegaardsvaegen 13
S - 433 76 JONSERED
SWEDEN
Phone: +46317956390
Fax: +4631583199
E-mail: matzr@sweden.dg.com Counter