Saturday, 1 May 2010

As a general piece of advice on the subject of building motorcycles, have a plan and stick to it, is pretty uncontroversial.

My original "plan" had been to get the R65 running, bolt some Ace bars onto it, make a bum stop seat, and call it a café racer. It fairly rapidly became obvious that the Ace bars weren't going to make for a happy riding position and they've been deleted from the scheme of things. However, the scheme of things now includes rather more than it did to start with, and one of the things it includes is me abandoning my resolution not to mess around with the frame.

For one reason or another, I seem to have mislaid the photo I took of the inside of the R65's fuel tan, which is a shame as it was a bit of a trial getting everything lined up, lit up, and in focus, and I was quite proud of the result. The point being that the tank has to go since it's rusted to the point where it's going to start leaking before long. So rusty in fact that the fuel cap had seized in the threads and required corrective surgery with a large hammer and a cheap screwdriver to remove it. Hopefully I'll have an R80 tank to go on there next week, but in the mean time, I've been looking at a Suzuki GS1000 tank as an alternative.

It is sort of growing on me, but I really would prefer the BMW tank. I think...

If you study the picture you can see that I've shortened the rear subframe, and bolted on some temporary foot pegs to establish the riding position. During the course of the week, I read somewhere that the lack of Ace bars or clip-ons means that my BMW won't be a "cafe racer", because it'll have the wrong bars.

Which is true enough, as it's a café racer, with an accent over the "e". I can see that having ape hangers on your motorcycle and asserting that it is a café racer (with or without an accent) is going to make you look a little foolish. But on the other hand taking a box stock motorcycle and bolting a set of Ace bars to it, doesn't make it a café racer and asserting that it does, makes you look equally foolish.

The point of a cafe racer is that it looks like a refugee from a road race track, and to delude yourself that bolting on a set of Ace bars achieves that must require some very determined squinting.

With all this interest in café bikes, I hear very little mention of Unity Equipe, which is a little odd I think. Check their site out, download the 50 page PDF catalogue and see if you don't think it a little odd too. They even have Ace bars...

As making it look like a race bike is the essence of building a cafe racer, I've been studying pictures of BMW race bikes as well as café bikes, and I've noticed something. That thing where you move the engine forward 1 1/2" and up about an 1" at the back? That really makes a difference to the way the motorcycle looks.

It didn't look like it would be a massive amount of work, and it really makes a difference to the stance of the motorcycle, so I decided to abandon my earlier resolve to leave the frame unmolested and to move the engine mounts to reposition the engine.

I'm curious as to what other people have done with the drive shaft though. I'm leaning towards machining a spacer to fit between the gearbox flange and the drive shaft flange as that will keep the UJ in the original position in relation to the swing arm pivot, but given that there can't be an awful amount of angular movement in the swing arm, and the drive shaft seems to have some sort of a plunge mechanism that might not be overly critical and lengthening the shaft may be an option.

Clearly, as the essential thing about cafe racers is that they look like a racing motorcycle, it isn't necessary for them to go like a racing motorcycle. On the other hand, the earlier R65s like mine made a heady 45HP, and the later ones a dizzying 50HP mostly through having larger valves in the head as far as I can ascertain.

So, now that I've snapped the threaded section that retains the exhaust nut off of the left hand head, I have a reasonable excuse to replace both heads with the later ones and gain 5 more HP...

For the time being, I'll be cutting the old engine mounts off of the frame and repositioning those, as well as looking at stiffening things up a little in general and tidying up the exhaust hangers to do duty as rear set mounts.

If you're wondering, I did fix the brakes, and I did ride it around the yard.

That's why it isn't having Ace bars.

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