Saturday, February 28, 2009, 04:09 AM ( 4664 views ) - Reviews - Posted by Administrator

This excellent reference provides invaluable information for the vintage racer or cafe builder. It is not a shop manual, nor a maintainance guide, nor a model reference. It does not teach you how to adjust your valves, or set luggage for touring.

What is does provide is detailed discussion of each component system- brakes, clutch, forks, etc. and show how each was improved and modified over the years. This is very important if you are building a bike from pieces, or building a custom, because although there is great interchangeability over the years 1970-1989, the differences that do show up are not always along model lines.

Do you know how to tell what flywheel will mate with what crankshaft? How to determine if a cylinder will fit a particular engine block?

For the racer this is vital because not all parts are available in early and late variations, so if you must go with a later part, such as a cam with a later style seal, what other parts will have to change to fit?

This is not a book for most BMW owners, because most are starting with a relatively complete bike, and if anything they're likely to return it to original stock condition. There are some negative reviews of this book on Amazon, but it's easy to tell the reviewers were confused about what it is about. To the layman restoration might be polishing a jewel that is 99% there already, and this book is useless for that.

That's probably the only negative about the book- I'm not sure it's exactly a restoration guide, as it isn't quite a reference to exactly how each model came from the factory. Maybe it's a customizers' guide, or a racers' guide, I'm not sure. One thing for sure, anyone contemplating putting a BMW airhead together out of a basket of ebay parts needs this book to determine what will fit.

You can easily see who the intended audience is- the motorcycle restorer who works in many different brands, and wants a reference to tell him how things are in this one, just as he would with a BSA or Zundapp. Yes, it's a book that assumes your expertise is enough to know what to do with the information. Like most references like this with older stuff, there's no hand holding. But it's fortunate that we do have this information- those of us who have worked on more obscure things like a Garelli would dream of such a book as this.

Highly recommended. Sorry to be reviewing a book that's not quite easily available, but try the used sellers, it's worth it. If you're building bikes, you need this one.

Saturday, February 28, 2009, 06:24 AM ( 10012 views ) - Reviews - Posted by Administrator

Not perfect, but most of us have one, the CLymer manual provides general information and maintainance procedures for BMW airheads.

What's not perfect? A number of typos have been noted, so check online at Snowbum's site to double check things like torque setting numbers. Also, the Clymer manuals are written by mechanics who tear apart actual bikes in order to write their reference material. However, they're not BMW mechanics, and they may not know the best or easiest way to do something. For instance, they suggest that in order to replace the clutch on an airhead, you should remove the rear end and driveshaft, bun in reality all it takes is to disconnect the swingarm pivotsand leave the whole thing hanging from the subframe.

That said, we all have one in the shop somewhere- why? Because it's a useful reference. It helps to look at pictures of things to remind yourself of, say, where all those wires connected to the alternator go. The wiring diagrams are useful and there really is quite a bit of useful info here.

Bottom line: a useful refernce if you take it with a grain of salt.

Thursday, July 3, 2008, 12:32 PM ( 2605 views ) - BMW Cafe Racer - Posted by Administrator
Since the original connecting rod bearings (and most likely the crank) had been well thrashed by their brushes with glory, a bottom end change was in order. Preserving the original r60/5 engine block and crank for possible restoration later, I stripped the bike down.

Note that I'm using an automotive engine hoist, and I recommend it when pulling motors. Not only does it provide 100% positive support that can't fall over even if you lean on it, but since you can't use the centerstand (it comes off with the engine mounting studs) you also don't want to use a motorcycle lift, because that would normally go right under the oil pan- and that's going to get lifted out of the frame.

So an engine hoist works wonders, and a five gallon pail like this one to set the frame on and keep it held steady is just the ticket. You probably can't see in the photo that I pulled the swingarm pivots and unbolted the u-joint and just pulled the whole swingarm and rear end free and left it hanging on the shocks. That's the easiest way.

I began building the new race motor using this good '76 R75/6 bottom end. The changeover from /5 to /6 meant a change in a number of things, including both flywheel (to bigger bolts) and cylinder base size. I could have used an earlier /5 block, but I opted for /6, even though it meant sourcing another pair of cylinders. (r60/6 and r60/7 are not exactly rare, but uncommon, so finding these was not so easy as it would have been for R80, R90, or R100 stuff).

But the tradeoff was worth it, because it allowed the mounting of this lovely flyweight aluminum flywheel (I'm not sure why the light makes one of the flywheel bolts look darker, believe me all five are new bolts):

But that's getting ahead of the story- of course there's a whole lot more three steps forward, two steps back stuff that I'm skipping over but you know it's there. Put it together and take it apart again. Because of course it's the old story: "As long as I'm in there..."

So, yeah. As long as I'm in there, what about another cam? Certainly the stock R60/5 cam could be improved on. But why not a racing cam? As it happens, the famous 336 cam that helped BMW dominate sidecar racing in the 1950's was still available. Whee!

Here we are pressing the timing chain sprocket off the old camshaft.

I'm skipping some ugly steps to get here. What does it take to swap a cam in an airhead motor? Well, besides the front cover you take the alternator and rotor off, and the timing cover, and there's a lot of disconnecting of stuff you want to be sure to reconnect right later. Under that is the timing chain, which on this vintage is a double-row chain running around sprockets on the crank and cam shaft.

And I'm gonna take a stand for being a heretic here. The first time I changed the timing chain on the RS, I cut the old one off, and that was fine, it was worn. This one wasn't worn. So rather than cutting it off and using a new one with a master link, I would rather use the endless timing chain, cause it's cool.

So what I did was used a puller to pull the crank sprocket off the crank -most- of the way but not all the way. If you do this, you can pull the camshaft forward far enough to get the chain loose and off. This is good because when you go to reassemble, the sprocket is correctly aligned on the crank and it's easy to press on- otherwise you have to heat and freeze parts and even then it isn't easy. So to me this is a good trick. I know, I know, the sprocket should be replaced, but if the chain isn't worn and neither is the sprocket, I say run it.

Anyway, here's the 336 cam, compared with a pair of R75 cams. Notice that in addition to the different size lobes, the top R75 cam has a larger lump on the end. That's where the timing cover seal is, and there are two sizes, small (early) and large (late). I chose to use an early small seal, because I wanted to use the original early timing cover that included the speedometer cable for the /5 speedo.

Now a closer look. You can see how much larger the lobes are on the 336 cam, almost 50% more lift and a lot more duration too (wider).

Here we are pressing the cam sprocket onto the 336 cam. Whee!

Every little bit helps when you're riding your cafe racer hard around corners. Years ago I'd come across a BMW police oil pan that included these baffles to prevent windage around corners by keeping the oil from sloshing around. Boy it's fun to pull a part like this out of your special parts stash!

Meanwhile, other changes were in store besides the engine. Having been studying details of 50's as well as prewar BMW's, I decided for fun to detail the cafe racer as though it were from an older era. One of the most striking details of some of the older models was painted rims. I considered all-black but instead opted for the black painted stripe rim of an R51/3. This and a black painted hub would do wonders to give the bike a vintage feel.

And even more important than a faster engine and better paint: dual front disk brakes! Here we see the first mockup with fork brace.

After lying in wait for so long (it seemed) the r60 cafe racer was finally coming back together!

Thursday, July 3, 2008, 12:30 PM ( 5559 views )  - Posted by Administrator
The first year saw a series of performance developments. The old exhaust fell apart (the worst parts of this period BMW are usually the seat hinges and the exhaust) and I soon replaced it with a Luftmeister 2-into-1 set.

The Mikunis were rather oversize- 32mm on a 600 twin is a bit much by conventional thinking, and I was warned it wouldn't work. Quite to the contrary, it worked very well. The little R60/5 had become a screamer, with characteristic neck-snapping Mikuni acceleration.

But soon it became evident that the two carbs had enough differences- in wear if nothing else- that a new pair was in order. I went through a series of jetting experiments and finally came up with a workable combination. Velocity stacks added a nice finished touch to the carbs. No air filter, that's right- fortunately the Northwest is rainy but rarely dusty, or I wouldn't risk it.

In this form I proceeded to ride the hell out of it, and had much, much fun. The front end was superb- although there was only about three inches of travel remaining in the front end, it was enough, it never bottomed out, and it was always reliable and well-mannered. Well, almost. It did suffer the classic 'rubber cow' head shake going around a fast curve with no banking- like certain highway ramps I know. A steering damper would help. But overall it was quite tractable, and fun.

As far as speed, the oversized carbs seemed to balance the oversized exhaust, and it was extremely quick, it would outrun most any airhead up to about 75 mph, and there it hit a brick wall and would go no faster. Clearly the stock valves and detuned cam were holding it back.

In this form I rode it to the National BMW rally in Spokane (conveniently held in 104 degree heat). It performed admirably all the way there and back again, although I wilted quickly in the heat. I made a steel bracket that mounted under the seat to hold soft luggage out of the wheel, and away I went- cafe touring bike.

It was then that vintage racer Charlie Baker kindly offered a set of R60 race heads with oversized valves. This removed the 75mph limit entirely- now it went well over 100mph with room to spare.

But I made a mistake with these heads- I tested them by installing them, and rotating the crank to see if there was interference between piston and valves. There seemed to be none, so I went racing. However, this is not the right way to do it- the right way is to check clearances everywhere, there should be 2mm of room to compensate for everything flying around at high speeds. I hadn't- and after a few months of thrashing, it developed a bottom end knock. Disassembly showed that not always, but during high speed operation the valves contacted the piston, hammering the main bearings which were now toast.

So back to the garage it went, to be torn down and rebuilt anew.

Thursday, July 3, 2008, 11:11 AM ( 1779 views ) - BMW Cafe Racer - Posted by Administrator
In the beginning it was a neglected '71 R60/5. The carbs and exhaust were shot and many little things needed care. I don't have a photo of it in this state but here's a magazine ad showing the model:

The short wheelbase models only appeared for a short time before they were joined and then replaced by a longer wheelbase model with an extra couple inches of spacer welded into the swingarm. This made for better stability which was a real improvement for touring with a luggage or fairing, but the short wheelbase made for a quicker, more nimble ride.

At the time the chrome tank and side panels were disliked, people thought they were gaudy and tasteless. Today of course we love these details, and they add a real beauty to the bike. This particular one was also set up with large front crash bars, a big luggage rack, and it hadn't run in years.

Then I came across parts of a San Jose nationals racer like the one below that had been built in the 70's, at a time when an airhead BMW (an R75/5) was the fastest bike in the world. Most of this vintage race bike was already gone, but I acquired the key parts- the lowered front end, modified subframe, and cafe seat. The rest- engine, etc.- I could build, but an expertly lowered front end was really valuable, and not something I'd want to build myself by trial and error.

I began to disassemble the R60 and installed the front end. The subframe was a stock subframe that had been cut down and braced, and fitted with hardware to mount the cafe seat. Short Koni shocks lowered the rear to match the front, and gave improved handling.

These parts transformed the little short wheelbase R60/5 into a serious cafe racer- low and fast. Most significantly, the San Jose front end lowered it drastically, lowering center of gravity and improving handling. It also made it look really wicked cool.

At first it was very rough, but it began to take shape:

Note the top triple clamp is not the usual stock stamped plate, but a heavy cast unit- actually a lower triple clamp flipped over and machined to fit- a classic period race trick. The next step would be to install an S fairing, and you can see the mounting brackets already installed.

In order to get it to run at all, it would need carburetors. I scored a couple of Mikuni round slide VM's on ebay- not from the same model bike, in fact one was from a two stroke. But Mikunis are tremendously adjustable, and I soon had them jetted, at least for starters.

When it roared to life, and went for its first test ride, it was clear tht this was a good combination- airhead BMW's feel good, but this one felt especially good. Lowering it made it handle better and increased the sensation of speed. I found I could thrill myself as much as I wanted without even going over 45 mph- what a perfect quality!

Looking back, I really prefer the appearance here as a naked bike, without the S fairing, and it was this picture that reminded me to try something different in the next incarnation.

Saturday, February 28, 2009, 05:15 AM ( 6522 views ) - Reviews - Posted by Administrator

The bible of safe riding- this book could save your life, or your buddy's life.

For years Seattle rider David Hough has been writing columns in Motorcycle Consumer News about riding safety. In each one he describes a risky riding situation and challenges you to think about how you would handle it. Then he goes into analysis of what can go wrong and how to avoid it.

This book contains a large number of these chapters, each one studded with diagrams and photographs of actual examples (many of them familiar to Seattle riders).

Also included is a lengthy analysis of the Hurt Report, which famously analysed injury statistics and determined the three things riders can do to best increase their changes:

1. Use the front brake. Riders who fail to do this- or who fail to cover the brake and have to hunt for it- crash.

2. Wear a helmet with a chin bar. Rider who crash without one get broken jaws.

3. Get in the habit of dropping 5mph at the first sign of danger or risk. This equals six feet less distance every second- and in most cases if you had six more feet of room you would be able to avoid a collision.

Finally, Hough speaks out against the biggest contributor to motorcycle accidents: drinking. While many riders wisely would never touch their bike when they're impaired, for many driking and riding is a lifestyle. Ironically, no injury or safety statistics about motorcycles take this factor into account, suggesting that if you ride safely, sober, your safety on two wheels will in fact be considerably higher than the stastics claim. Friends who work in ER tell me the same thing.

This is one book EVERY rider needs to have on their bookshelves- if you're a veteran rider it's fun to challenge yourself to see if you have room for improvement. And once you've read it you'll wind up lending it out numerous times, because, well, you can't bear the thought of a buddy riding and NOT knowing this stuff.

It could be the perfect gift- good entertainment that could save your life.

And now there's a second volume! Don't pass up the chance to learn something new that increases your safety!

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