Thursday, February 2, 2012

BMW Airhead Throttle repair

The hard-starting problem on the R100RS finally made itself obvious. One of the choke (well, excuse me--ENRICHENER. Geez.) cables broke the rest of the way, and it really, really only ran on one cylinder. The fix for that was obvious--order new cables. No problem.

The "While We're At It" syndrome set in, of course, and improvement of the throttle was well overdue. I ordered the throttle cam/gear, to go with the newish throttle tube I had already gotten from Ebay long ago. Here's how it went:

This can't be right!

The original cam/gear had a stepped bore to match that stepped post in the throttle.

Checked with the folks at Bob's BMW, and it turns out that this cam replaces the old one, but you also have to buy the cover to make it work.


'Nother $25, 'nother few days.


I could justify my ownership of an antique lathe, and make this little spacer.

It looks like this going together:

And this after it's in place.

Uh-Oh. Now the throttle cover doesn't hold the new cam down like it's supposed to. The big hole in the cam just slides right up over this projection on the cover.

Another lathe job. Rummaged up a washer that's the right thickness, and cut a big chamfer on it to clear the radius at the bottom of the peg.


Here it is, in place, held by the miracle of superglue. Works fine. Way more trouble than just buying the dang cover, but better than spending and waiting.

Two of my least favorite activities, those.

OOoooooooooooo.....another opportunity!

That throttle tube is just hideous. Way too big around, and it's a gross, as-cast surface with huge parting lines sticking up.

That's why the right grip always seemed too big and lumpy.

Chuck it up in the lathe, and......

OK, now THAT looks like a part that should be on a fine German machine.

And when I get around to putting on my nice, thin, diamond-knurled Renthal grips, they might actually come out the right size.

Here's another un-German oversight.

They stamped the part number into the handlebar. That's nice.

Did it right where the throttle tube is supposed to rotate smoothly. Not so nice, because when they stamped it, it made a raised edged all around every letter.

A few minutes with a honing stone has it all smooth.

Added a few other tweaks, like a new rubber boot on the cable where it goes into the splitter, and safety-wire on the two cables leaving the splitter, to keep them from ever trying to jump out and make the throttle stick.

And now....NOW, the throttle works VERY easy and VERY smooth, and if you let go of the grip, it CLACKS! back to idle the way I like.

Another pet peave addressed.

Oh, yeah, the original project, putting on new choke cables, also worked fine.

Just had to make one part:

That's what the parts breakdown calls a "Piston" in the cable splitter. The plastic one came out is several pieces. Can't buy that part, only the entire assembly. So, rather than spend and wait, just make one out of aluminum!

How did I ever live without a lathe?

Bike works so well now that I feel compelled to paint it.

Jess, Winter of 2012

Saturday, June 27, 2009

Shop tricks 1

I hate to lose parts. I hate to have parts mixed up. I've seen all sorts of clever schemes for keeping track of valve-train parts. I've spent all kinds of time twisting safety wire around parts like valve-stem locks in attempts to corral them withe the right valve, and keep them from getting totally lost.

The little light bulb went on today, finally. I needed to keep all the parts associated with a valve together, this time because I have an extra one I want to peddle on ebay. I cut a short piece of .25 fuel hose, slid it over the stem of the valve, then put the valve locks on stem and slid the hose up and over them. Like this:

Wow--that works nice. Dropped the whole mess into a ziplock bag, with complete confidence for the first time that all the pieces would still be there later.

Sunday, June 21, 2009

New Bike--BMW

Well, Craigslist comes through again. Found an ad for a 1982 BMW R100RS, one of the bikes I've always admired from afar, but never seriously shopped for. The nice lady bought it from her aged uncle, the original owner, for her first bike. It's heavy, tall, long, old, and a bit rough. The nice lady was none of those things, and wanted a bike that was easier to ride. I trailered my '03 Honda 750 Shadow:

Trailered because the BMW may or may not run--mysterious battery/charging problems. Plus, it was going to be a couple of hours in the dark through deer country to get home, on an unfamiliar bike with electrical problems.

She liked the nice, low, easy-to-maneuver Honda, didn't have a problem with the "Rebuilt" title, and we made the swap.

I spent part of Saturday cleaning, waxing, and dinking around. Also discovered that Uncle Fred's electric vest is several sizes too small to zip around my muscular figure, and that the bike he put 48,000 miles on is hideously uncomfortable. I removed the very nicely-done rearset pegs and controls, put on the stock stuff, and it's transformed! Very, very comfortable, now.

I always thought of myself as a kind of sporting rider, and here I am REMOVING rearsets. My knees are 85 years old (according to my orthopedic surgeon) and just don't bend that far. (The rest of me isn't nearly that old, and the knees have never been out of my sight, but who am I to question a doctor?)

Also confirmed that the BMW factory is located in a part of the world where 85 degrees is considered blisteringly hot. The R100RS has the reputation for being very nice when it's cold and rainy. I can't speak for that, but I have proven empirically that the fairing routes a lot of engine heat to the rider. Not really what you want when it's 101. Taking off the fairing lowers pretty much fixed that, and I think that when I rebuild the forks, I will leave off the rubber booties and let a little more air in to evaporate the sweat on my hands.

Heres the sinister black beemer as it stands now:

Trying to decide what color to paint it. It's a well-done package in black, but it's not really what I want, and the paint isn't in great condition. I was convinced that Britsh Racing Green was it, then a dark metallic green, and now I'm actually thinking a candy-apple red. Gonna have to narrow that down a bit.

Probably will powder-coat a bunch of the brackets and bits and pieces like the valve covers, and maybe polish a few choice aluminum parts.

Not sure I want to take it apart for that--I'm kind of enjoying riding it too much.

Tool Kits for Motorcycles

I seem to put together a lot of tool kits. Having spent my formative years driving a variety of motorcycles, cars, and trucks that tended to be from the less spendy end of the spectrum, I assume that whatever I'm driving will probably break down.

And the more interesting the bike, the more likely it is to break down.

So, I'm always on the lookout for compact tools.

And I'm not so much on the lookout for clever devices that purport to "fit all sizes of bolts", since such things are just not natural or right. I even feel a little twinge of guilt when I use a crescent wrench.

Here's the one I put together today:

There's a 1/4" drive t-handle, a long extension, a bit adapter to take screwdriver bits, a little plastic holder full of bits, a really long phillips bit, and 4 sockets.

By no means everything you need, but it does cover pretty much every fastener below 10mm, which is most of them on a motorcycle. Some bikes don't need the long phillips, and there's a couple of torx bits that are useless on most, but the germanic part of me can't just leave them out--I mean, there's even a little PICTURE of the torx thing printed on the holder.

Here's what it looks like all bundled up:

Pretty compact. The sockets slide over the handle of the t-handle, and are secured with a ziptie. I had to drill the center of the socket out a little to do this, but some brands have a big enough hole stock. You could also secure them with a little wire, or a short piece of fuel hose.

One of the problems I have with a lot of commercially-available attempts to do this is that they aren't very compact. They might fold up very cleverly, and have a spot for everything, but the people that design them just can't pass up the opportunity to make them all "ergonomic" and plasticky, which makes them bulky, lumpy, and not suitable for going into a tool roll or tool bag.

When this is bundled up in a toolbag, there's hardly any air, almost no plastic, and everything there is actually useful.

Now if I could just figure out how to compact a set of combination wrenches.......

Wednesday, June 3, 2009

Inspiration for the street-tracker Part II

Well, that last post wandered badly off-course. What I was going to do was show some photos of street-trackers that catch my eye.

This one's from Cycle World, I think. Blue version of the yellow--no, wait--it was YELLOW one that I saw years ago.

Now this one is just about my favorite.

For some reason I have no desire to paint it up like a race bike, nor to have giant numberplates. I noticed that when I quit racing MX, I never again put a number on the numbeplates of my dirt bikes.

Inspiration for the street-tracker

In the countless unprofitable hours I've spent looking at what my lovely wife refers to as "motorcycle porn", I have saved a few photos. Actually, whenever I run across a photo of a motorcycle that appeals to me, I save it. You can learn something about yourself by doing that--what I learned by scrolling through that pile of pictures is there are a few common threads in what seems a totally random collection.

I like machinery.

Most of the bikes I like seem to have engines that, well, sort of...stick out. Hang over. Poke through. Lots of old airhead BMWs and Moto Guzzis. Honda CBXs appear. Odd contraptions with Volkswagen engines. Very little in the way of bodywork. Not many regular sportbikes. More Ducati Monsters than 998s.

I'm sure this could all be Freudized into somthing disturbing, but I think it's entirely innocent--I just like stuff that does stuff, and have no affinity for things whose only purpose is to hide the interesting stuff.

Street-Tracker 650 Yamaha

Yes, I know. Everyone's building a street-tracker, or maybe everyone's already got one. Doesn't matter--I still want one. I have a deep aversion to buying anything that I can build myself, as well as the kind of attachment you can only develop for ideas that you thought up all on your own.

That's right. I invented the street-tracker. Stood right there in Dave Best's Harley shop in about 1984, staring at the immaculate Shell/Champion 750 Yamaha flat-track bike, and thinking "Man, what a cool thing that would be--put a headlight on that puppy, sweet-talk your way to a license plate, holy cow, wouldn't that be the fastest, lightest, best-handling thing you could ever ride on the street?" Everyone I mentioned it to gave me the look. No way I was going to build the thing, you understand, nor buy it--if it wasn't a motocross bike, I really had no use for it at that point in my life, but the idea was just sooooo neat.

So now that the dang things are almost a fad, I'm jumping on the bandwagon and gonna finally get one my ownself.

My brother-in-law Byron found me the bike at a yard sale while I was off on vacation, and through a complicated cell-phone multi-party negotiation, bought it for me and even hauled it home. My wife thinks he's a bad influence; actually she thinks we are kind of simultaneous bad influences on each other.

Here's the $400 beauty:

Well, actually, that's it after I took off the dumb apehangers. And cleaned the carbs so it would run. And made a few illicit runs to town on it just because it's a motorcycle, and it runs.