'Blauwtje': A very special BMW R45

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Maurice Hünen is a Maintenance Supervisor, genetic engineer, motorcyclist and politically active. Maurice is a good acquaintance that we have regular contact with. His BMW 'Blauwtje' was once such a non-burning BMW R45.

Recently Maurice has an R1150R. And maybe his unique Blauwtje will go away. "Lack of space". It is something. We wondered how that process actually grew.

Maurice tells Blauwtje's story

“It was in 1995 that my wife, without consultation, registered me for motorcycle lessons. I could not possibly give her unequal.

Because often I was tinkering and adjusting other people's motorcycles. And when I asked in detail about the behavior of the bicycle, I was often told: "Boy, grab a helmet and go ride yourself with that thing!" They too were right.

But even then it is better to drive with than without pink paper.

During the lesson period a BMW R45 presented itself to undergo an adjustment course by me. And then it happened.

I immediately fell in love with the boxer

Modest, with a beautiful color and full of possibilities. From the moment his owner offered him for adoption, he would now live with me. But a happy marriage with the performance of "Blauwtje", the name he would be called from now on, was not.

Blauwtje also needed a lot of small mechanical care. Care that ranged from overhauling the centerstand, which is now dragging on the asphalt, replacing the worn-out gas handle, replacing the front springs and loving the sprinkler occupation because Blauwtje was excessively thirsty.

And much more.

Oh well ... books can be written about it, but anyway, the 'quest for power' broke out. The 27 horses in the stable soon proved to be too little when I climbed the Limburg hills with my now loyal vassal, completely legally with pink paper in my pocket.

Only the sight of a bag full of groceries made him get all the sweat on his cylinder heads.

A lot was eventually changed. The objective was more power with less speed. It all had to happen to discreet things without sacrificing astronomical amounts.

And that would work!

It started with 650cc low compression pistons.

In this way the existing heads could still be added and nothing really needed to be adjusted. It saved a sip on a drink.

And those little valves? They were part of the concept. Because in terms of gas flow, tight channels are not necessarily wrong.

Immediately after the adjustment, the short final transfer immediately became a sort of thing.

The block was running too much on the motorway. And so a transmission of the R100 was mounted quickly. That saved a lot, but well, now there was of course too little pull for that long transmission.

Fitting a twin-spark system brought life to the brewery.

Faster on the gas and more power. Beautiful! But it wasn't over with that. After slight adjustments to the cylinder heads, 650cc cylinders were fitted with standard pistons. The compression ratio almost went into the wings! Blauwtje almost became a diesel. This was necessary to increase the thermal efficiency of the thing. Do more, with less fuel.

Blauwtje would then develop an equally completely different walking behavior with an advance curve that was completely adjusted in the distributor.

Very adjustable and considerably more torque. And even with the very tame '284' camshaft, he went very fast.

32 mm gas plants and the suction pipes of the R100 have already been installed. Without this it would have been the end of practice.

Too narrow airways, and therefore far too much resistance.

Large channels are not always great. But running with a too tight border on your T shirt? That makes you miserable.

Anyway, that was solved effectively. With a nest of young nozzles, the right size nozzles were quickly found with some experimentation, after the air filter had also been replaced, by a K&N air filter. A real K&N filter. The Chinese things that 'look like it' are real power killers.

The result was disappointing.

The exhaust was also a thing in itself. Equipped with a balance pipe in front of the engine block and one behind it from the factory, the possibilities for improvement had already been given. In the context of the developments, the balance pipes were both replaced by stainless steel expansion dampers, in order to raise the resonance frequency of the outlet in the front part, which produced a considerably improved 'scavenging' effect.

The sprayer occupation could again be determined. The effect on power development turned out to be amazing.

Now of course you are wondering what all this will have delivered.

The acceleration of 0-100 moves towards the 5 seconds.

The original consumption of more generous than 1: 15 (!) Was brought back to 1: 19.

130km / hour is half gas cruising and the engine temperature has dropped.

The top is around the 160km / hour in its highest gear.

The block does exactly what I had in mind with this project.

Although more power, all this happens at 41% less revs and therefore much less mass forces. This saves the block that all this performs quite well. An oil cooler has also been installed to provide certainty. He does his job properly.

To keep everything on the road in the right direction, the front springs were replaced by progressive ones from Hyperpro.

The rear springs and shock absorbers were replaced by copies of IKON. The steering part received a steering damper and the left front brake got a little brother on the right side.

The total end result is a machine that is no longer comparable to the original. Yes .... except for the latest appearance. Blauwtje has really become a 'sleeper'. A very potent machine with the looks of father's shopping bike.

In the 0-100 sprint, Blauwtje is in no way inferior to a K75.

Apparently everything with an original BMW ... but slightly different.

Stable on the road and mature.

Just bend over and the lower spark plugs become visible. They are actually the most striking of all the changes. Oh yes ... that's because the spark plug caps are now red.

Blauwtje now has a newer brother in the stable.

After 24 year there is a new challenge with an R1150R.

Blauwtje needs exercise. After all, it has become an athlete.

A good new owner was not an unthinkable idea.

Blauwtje is a very grateful bicycle! ”







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  1. What year is this R45? It looks like it was delivered from the factory with a touring handlebar and a windshield. In '82 or '83 I bought one exactly like it, new. But the power was such that I shortly afterwards bought a two-year old R100RT. Kind regards, Gerard de Smidt

  2. Hi dolf,
    Where did the tenant in your title go?
    Would be a nice bike for my daughter.
    Looks factory-enhancing. I think that's a real compliment at BMW 👍

    • Hi Rjab, I was a 'hired wordman' for years. And I was satisfied with that. But someone else apparently also thought it was a great name. And he registered him. And then you may no longer use your historically grown name. "Because it belongs to someone else." Of course you can appeal against anything. But that costs money and time. You should just contact Maurice. He is one of the nicest people I know and a genetic engineer. Maurice Hünen

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