|Posted on Friday, October 19, 2007 - 11:39 am: ||
I had a nice time playing on the KLR250 last saturday... I was getting tired of always riding around treating this thing like a street bike, and just riding where things were easy. So I decided to keep trying harder and harder terrain until I dropped it (all low speed really technical stuff). I wanted to find out whats really possible, and where my skills could improve.
So I found that point, and dropped it on the left side (was going too slow). Crunch... there went the left mirror (perch had been broken before I got it, now it's broken worse, shoulda thought to take off the mirrors). Pick up the bike, take off the surviving right mirror, try again faster.
Crunch. Dropped it on the right side. There went the turnsignal (cheapo aftermarket bullet type added by previous owner).
Try number 3... made it across. Then noticed my rear brake lever was now bananna shaped Guess that's it for today... rode the bike back home.
It was actually a lot of fun. This is a heavily used 1985 KLR 250... there is not a part on it that was not pre-scratched or dented by a previous owner. I bought the thing for under $600. Having a "droppable" dirt bike was a real plus for me. I don't care about going really fast on the dirt, and don't want to take big risks, but I do want to be able to go almost anywhere I want (slowly if necessary).
It's fun to start learning how.
So, because I am a cheapskate, and because there are apparently a lot of Japanese accountants that are determined to squeeze every last bit of profit out of this bike (I just bought 3 gaskets for this thing for $60 ), I will cobble / craft / fix a part before I will buy one. I only buy what I cant build or buy (i.e. some proprietary gaskets).
So first I fixed the brake lever that I bannana'd.
It unbolts easy enough, but it won't fit out between the case and the foot peg. Try and pull off the foot peg... no way that big bolt is moving (though I didn't have the right socket for the impact tool to try that). With enough patience, and removing the pivoting part of the foot peg, I could wrestle that brake lever out.
Heat it up with a propane torch, and pound it back into roughly the right shape. I had to bend it a few times to get it back into a position where it would both sit in the right place, but still wiggle behind the (still stuck) footpeg bracket. There is a shape that will do both, if you are patient enough to find it. Hit it with a can of flat black paint, and put it back on.
Then I notice that the bracket the pivoting part of the foot peg mounts in (which has been bent at least three different ways by previous owners) had a cracked weld. Doesn't really matter if it has been that way for a while, or if I just did it, it's still cracked.
So I break out the oxy acetylene gear, heat it red hot (still on the bike, as I can't get that bracket off) and use pliers to pull it back into roughly the right shape. When you heat steel like that red hot, you can easily put it in any shape you want. Then I put a new bead along the cracked original weld, let it cool slowly, and grind it down to square corner so the rest of the peg can still pivot when reassembled. Then more flat black spray paint.
Then, since I had the torch out anyway, I went to work on the left hand mirror perch. A big chunk had been ripped out by a previous owner, and I took most of the rest of it out with my drop. It is some kind of universal Japanese motorcycle aluminum potmetal substance where the mirror mounts, but it is screwed onto a plastic cover for the turn signal assembly on the other side. Don't want to melt the plastic, so I pull it apart and put it on the vise.
Aluminum is a bear to weld... it does not get red then white then puddle, it just oxidizes immediately, then suddenly when it reaches the melting point, it just all goes to liquid and drops out from under you. The layer of floating oxidation and the low melting point make it *really* hard to weld. TIG welding would help, but us cheapskates don't have TIG units
So I break out these "alumaweld" rods that I got at harbor freight and decide to give them a try. They aren't really welding, its more like brazing. I don't know what all is in it, but it melts at a lower (barely) temperature then the aluminum, and mixes with the aluminum you are working on.
You have to clean everything thoroughly first (easy enough) then heat up the part you are welding on. The exposed aluminum oxidizes immediately (aluminum oxide has a much higher melt/burn off temperature then aluminum, so it's always there, always on the top, and always a problem). You then use these rods to 'scratch' at the thing you want to join, and they puddle up, and you scratch through that puddle to get under the oxidation. I think whatever they are probably absorbs the aluminum oxide (you know, the stuff they make sandpaper out of) and tries to get it out of your way.
It takes a little practice to get the melting point right, so you don't just melt a hole in the thing you are trying to fix. And it takes even more practice to be able to build up a new feature (rather then just joining two pieces of metal), but I get it going fairly quickly and build up a fairly big and ugly knob of solid metal where the old mirror hole was.
I then hit that with the grinder and then the dremel tool to shape it into about what the original mirror mounting post support area looked like. Remember, its now a solid chunk of "stuff" (whatever that alumaweld is).
So I hit that with a drill, and re-create the hole for the mirror. My hole was off center, so it dropped into he open side of the housing towards the bottom. Not a big deal, it's hidden and had plenty of metal supporting it, but I didn't want to have gunk getting in there if I removed the mirrors then went off roading. So I put some quick dry epoxy on the inside, and built it up, so there is no path down that mirror hole to the inside of the housing.
Then I hit the hole with a metric tap of the right diameter and pitch (those Kawasaki mirror holes are exactly the right size for Buell XB-S mirrors, which I had laying around since I replaced them with bar ends on my XB9SX, which was good because a previous owner lost the stock mirrors). That alumaweld handle the tap nicely... it felt like aluminum, and it was easy to machine with hand tools.
Then more black spray paint, and put everything back together. Looks fine... (maybe even a little beefier then new).
The turn signal had just ripped out the mounting post from the plastic housing as well, so that threaded right back in, though the bulb is now blown. I'll have to look at some flush mount LED units to make them a little less fragile.
It's nice to have a bike that I am not afraid to drop, and that I am not afraid to weld / kludge. It's good practice for light and low stakes fabrication...
|Posted on Friday, October 19, 2007 - 04:24 pm: ||
What, no flesh torn, no blood, no explosions, no fire alarm, no burnt human offerings? You must be some kind of professional.
|Posted on Friday, October 19, 2007 - 04:52 pm: ||
I left those parts off. This is a family site, after all
Whoda thunk wrecking a motorcycle could be so much fun!
As I had to drag that thing back on it's feet, flopped flat with tires pointed up hill, on a 40 degree or so slope of moguled loose dirt, I was pretty darn happy it was not a Ulyses!
|Posted on Saturday, October 20, 2007 - 10:04 am: ||
since I had the torch out anyway,
Lots of my home workshop horror stories begin with those exact same words!
|Posted on Sunday, October 21, 2007 - 01:32 am: ||
I wondered if that stuff worked. Thanks for the run-down.
|Posted on Sunday, October 21, 2007 - 08:48 am: ||
It's not magic, but it definitely seems to have a place. I'll keep a supply on hand.
It will feel like it won't work when it starts, so practice a little and be patient. And there is nothing precision about it, so expect to make big ugly joints and globs that you will later machine down (hand tools work great).
It won't really work with propane, but it would probably work fine with MAPP gas.
|Posted on Thursday, November 01, 2007 - 05:56 pm: ||
I used to use AlumaLead back in the 70's it is an epoxy compound. I don't know if it is available yet. It was great for filling in hollow or weld joints and machined or drilled and tapped good. But was a bear to remove. I used it on my 74-74 Harley frame to smooth out the weld joints and gussets before painting.