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River City Beemers |
ShopDoc |
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Table of Contents: August 1996 Some of us monkeys make proud work. It’s work to save money, rather than to pay the shop. It’s work to learn how the bike operates in case our breakdown is out in the middle of nowhere and wouldn’t it be great to be purring down the road after a few minutes of tooling. It’s work just to find what makes these grand machines go. It’s work that gives pleasure just to be doing motorcycle maintenance because for some is found a higher calling. Everyone has his own particular mountain he wants to climb and wrenching is mine. Example. I was starting from an intersection but the slash 7 killed, very unusual. A little further, and it almost killed at a start again so I made note to look into it later. The next day after work I noticed the smell of gas as I was loading the saddlebags, and a drip from the left carb was making a large spot on the ground. My first inkling of trouble was the motor wouldn’t turn over. The headlight was good intensity, so instead of a charging problem was the starter the problem? On checking the tank, instead of 1/3 full, it was empty. I get some gas to go home on. After the fill up from a Jerry can the left carb was really dripping fast, so I turn off the petcock. Now the engine wouldn’t turn again even if I roll the bike in high gear thinking a bump start would be the answer. The earlier rough start up and dripping left carb tell me several things. Something was wrong with the left float mechanism and if that was flooding, it could give poor power and maybe till up the left combustion chamber. I’m still at work you see, so on removing the left spark plug and turning the engine( it turns easy now), gas sprays out the spark plug hole. Liquid won’t compress, the left piston is wedged against a liquid mass, hence no turn over, and probably the intake valve was open while the carb was overflowing with gas filling the combustion chamber. The slash 7 now starts but in the fifteen-minute trip home, Snappy is running more poorly by the minute. At home I roll up the sleeves with a good idea of what my problem is. One drain bolt removes the float bowl on the left Dell Orto to show the float wedged open by a lose float needle valve seat. This threaded brass fitting was unscrewing over the last two rides getting more symptomatic as engine vibrations turned it out. I tighten the seat. As a precaution I measure both float levels and find the offending one off 3 mm. This is corrected and after reassembly the bike starts but runs erratically. If I hold the throttle position, the tack needle wanders back and forth on a 400-rpm excursion. Sounds like, so I look for, but can’t find a leak in the carburetor system. With no other ideas I’m back to basics, the tune up. Points and timing are OK. Valves OK. Something could be wrong with the carbs but before taking them apart I check the plugs. The left plug is light brown to gray, OK. I clean and gap it. The right plug is black and wet. Then I remember the gas sucking into the combustion chamber and immediately dive for the dip stick. Sure enough the line is 2 cm above the full mark. This high level is escaping by the crankcase ventilation system into the right carburetor and flooding the right cylinder with the crank case contents. I drain the crankcase of a very thin gassy smelling oil, being sure to drain the oil filter and put in new oil. By this time I have the carb stix on the carbs since I’ve been working on them and it’s easy to do. On firing the slash 7, I immediately experience its soft purr at idle and it runs smoothly up the tach. I make a few minor adjustments with carb synchronization at idle and 3K rpm and adjust the idle and we’re like new again. It was obvious that the crankcase breather valve was shooting this overfull mixture of gas and oil through the right carburetor and fouling the right cylinder making the engine run like there was an air leak somewhere on the carb side. I’m glad I thought this out and did some easy investigative steps before dismantling the carburetors. Sometimes I find the answer by going the long way but that would be OK since I love the work. Today I had a fruitful repair. Bruce L. Hilger #62902 The motorcycle turn is a most fascinating feat. I clarify; I mean the act of getting off a straight course. Recently, while riding with the group in Redmond, The Chief Joseph Rally, I was a little off course in a gentle turn and all I did was push the inside grip. I had one of those really great feelings. I became keenly aware that I had tightened up the turn and was following the road. As I found, this move was terribly easy and quick. Historically the counter turn was a natural for me. I swing the bike out, lean in and the line I am now following is a curve. I love the gravity defying effect because suddenly I am hanging out, looking down at the ground rushing past me. To repeat the mechanics:
Heretofore most of my turns were good but I would sometimes find myself off. And I was usually running wider, than tight, in the turn. The adjustment to change my turn line seemed to be "complex", what ever it was and I had tightness in the act. As a result, I rode slower because adjusting my turn was too involved. And it often meant entering the turn at the wrong speed. I felt I could go faster, better, with acquired skill. After my revelation, I hadn't gone a quarter of a mile 'til I figured out what I had done. The very next turn, I initiated as usual and as I got part way through, did my push thing (pushing the inside grip). I suddenly realized there was no limit and I could push the grip until the bike was literally horizontal to the ground. A few days later I added a second maneuver, to push the other grip, and straighten the bike upright. The bike and I were proudly doing a new jig. How was this new information such a shock to me? It you think about the counter turn, the greatest effort, and slowest part of the turn mechanism is getting the mass (bike and rider) off its straight course and getting it to fall left or right. It one thinks in terms of vector forces, it takes longer to begin the fall from the upright position than it does from the lean position, assuming the fall is the same distance. Working with calculus will show this. Think of a logger when he cuts down the tree. He has time to shout timber, and run to safety. If the tree were at a 45-degree angle, log cutting would be a different story. Another factor is, you are driving the bike out from under the center of gravity, This means, turning from a turn position is a faster, easier move than turning from the upright position. And this adds the push turn to the counter turn. Since that time I have enjoyed adjusting my turns with the grip push. I have found I enter turns with greater speed and confidence. However I seriously doubt I'll be scraping the pegs like you good guys and when I finally pull in after everyone has gotten off their bikes remember he was pushing his turns. Shop Doc Hilger, #62902
How many of you own a torque wrench? Looking around some members garages garages suggests that other than the BMW supplied tool kit some of us may not have much more than a couple of adjustable wrenches and our do-everything favorite the Vise grip. A story could perhaps change your mind. Coming into Quincy for the 49'er Rally, on a heavily loaded K (even with no equipment at all, with your webmaster aboard, it falls into the "heavily loaded" category) on a sweeping downhill I felt a very significant wobble that was a new and unwelcome experience. I eased it down, the wobble receded, and being close to Quincy, I glided into town. My first thought was that perhaps with my heavy load, the bike was less stabile and that maybe the steering head bearing tightness needed to be adjusted. In the arrival excitement, greeting of friends and getting unloaded process the incident dropped back into the "I'll think more about it later" space in my cranial storage drawer. When the lunch bell went off we rode into Quincy for lunch and on the return when stopping I experienced a low speed "judder" that was unnerving. This time I was smarter and investigated. To my immediate amazement and subsequent retrospective terror, I found my left front brake caliper was missing one of its two bolts, and the second was backed out half way! The caliper was being held on by the brake hose and the disk! Let's talk about EXTREMELY FORTUNATE that the road into Quincy is marked by broad sweepers where engine braking is usually enough. Substitute tight twisties and you might be looking for a replacement webmaster. Who or what was the culprit? A quick mirror check revealed the guilty party. Thinking safety, before the departure I had removed my front wheel to have a tire changed. It is a simple process, but does require removing both brake calipers to let the wheel release. And on reinstalling, I had "guestimated" the amount of force or torque necessary and more than likely had only finger tightened the left side caliper. Oh, I had the torque wrench within sight distance, but I would've had to dig out the metric allen sockets, and that I guess was too much trouble. So on the right side I was ok, but on the left I had guestimated wrong. The vibration on the wheel, and brake assembly is significant and the 100 plus miles was enough to back out the bolt. Most of us, if we do any of our own maintenance at all, or ever have a flat on the road, will pull a wheel from time to time. And we each can fall prey to the loose bolt syndrome. The BMW caliper and the design requires a properly tightened bolt to hold in place. "Properly tightened" means a measured amount of torque appropriate to the bolt and the fixture and applied by a torque wrench. Each bolt on your entire motorcyle has a specified torque setting. What is this "torque wrench" business you ask? Torque is a measure of rotational force applied, and is measured as a force applied over a distance, e.g. in the English system, most commonly in pounds over a one foot distance, or "foot-lbs". For example put a one foot long socket wrench on a bolt and then hang a 1 pound of weight on the end so that it is at right angles to the wrench, and you are applying one foot pound of torque. Your owners manual has the torque settings in a table in the
back.
If you transcribe the settings onto the illustration in your owners manual, they are readily at hand for use. Proper use of the torque wrench requires setting it to the desired setting, then tightening all of the bolts light to moderately snugly with the regular wrench, and then in turn finishing tightening them with the torque wrench according to its directions. My wrench does a "click clunk" that you can hear and feel to let you know you are there. Note that OVER TORQUE-ing is not a solution to overcome the lack of a torque wrench either ... you can warp the caliper and cause binding, or premature wear on the disk. This could even conceivably require replacement of your forks. If you don't have a torque wrench, then go buy one. A good middle of the road reliable unit is a Sears Craftsman wrench. They have two styles. The micrometer adjustable model (the preferred better design) is $70, and the beam type, while less desirable, is still acceptable and only runs at $20. A heckuva lot cheaper than the consequences might be. Also, buy a set of 1/2 inch drive metric allen sockets as well. You'll need them for the torque wrench. What happens if you have to remove/reinstall a caliper on the road and your torque wrench is back in the garage? Do your best to guestimate the torque setting and then, at every stop do a finger check of the caliper bolt until you get back to properly retorque them or have them checked at your dealer. The official BMW statement in bold print is:
What happens if you really are unfortunate and lose the bolt? Well the good news is that BMW uses standard metric sizes here, and you can walk into most any hardware store and find a metric bolt section that will have a bolt to install as a sub. Take out one of the bolts from the other caliper to take in as a measuring gauge. Also you need a washer, and the flat washers are a different size for metric but usually they will have that also. For those who say, "It'll happen to the other guy", Randy Felice at A&S tells me he sells a "lot" of caliper bolts, usually quietly to sheepish-looking fellows who don't proudly show off their new purchase. Why is that do you suppose? Do they think that new bolts make one's bike prettier? I suspect otherwise. Lessons learned at others expense are always the cheapest.
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