If all else fails, you have gone through the previous two links and still can't figure out your problem, I will now teach you a fail-proof method of figuring out what is wrong with your bike.
The information contained in this website should be viewed as common shortcuts which I have found based on my experience. All that I am teaching are the usual causes of common problems. However, there are of course many uncommon problems, as well as unusual causes of common problems, and unusual causes of unusual problems, and usual causes of uncommon problems, and these may be motorcycle-specific or so unusual that my experience will not prepare us to diagnose and repair the issue. In these instances, the use of deductive and inductive reasoning to power scientific experiments and thereby employ the scientific method to solving the mystery is key. I have resorted to this method a few dozen times in my motorcycle repair history, and no problem has been left unsolved. So here is the method, as illustrated by the incomparable Robert Pirsig, in Zen and the Art of Motorcycle Maintenance:
"For this you keep a lab notebook. Everything gets written down, formally, so that you know at all times where you are, where you've been, where you're going and where you want to get. In scientific work and electronics technology this is necessary because otherwise the problems get so complex you get lost in them and confused and forget what you know and what you don't know and have to give up. In cycle maintenance things are not that involved, but when confusion starts it's a good idea to hold it down by making everything formal and exact. Sometimes just the act of writing down the problems straightens out in your head as to what they really are.
The logical statements entered into the notebook are broken down into six categories: (1) statement of the problem, (2) hypotheses as to the cause of the problem, (3) experiments designed to test each hypothesis, (4) predicted results of the experiments, (5) observed results of the experiments, and (6) conclusions from the results of the experiments. This is not different from the formal arrangement of many college and high-school lab notebooks but the purpose here is no longer just busy work. The purpose now is precise guidance of thoughts that will fail if they are not accurate.
The real purpose of scientific method is to make sure Nature hasn't misled you into thinking you know something you don't actually know. There's not a mechanic or scientist or technician alive who hasn't suffered from that one so much that he's not instinctively on guard. That's the main reason why so much scientific and mechanical information sounds so dull and so cautious. If you get careless or go romanticizing scientific information, giving it a flourish here and there, Nature will soon make a complete fool out of you. It does it often enough anyway even when you don't give it opportunities. One must be extremely careful and rigidly logical when dealing with Nature: one logical slip and an entire scientific edifice comes tumbling down. One false deduction about the machine and you can get hung up entirely."
-----I would like to interrupt Robert here for a second, and emphasize this point. This is the major downfall of both the amateur and professional mechanic, and the stumbling block which I encourage all the people who contact me with problems to see and overcome. The vast majority of people who contact me have made certain assumptions about their bikes which often lead to the root of the problem. Example: bike doesn't run. They are struggling with the carbs. I ask what the compression is on all cylinders. "Oh compression is good." What is it? "I don't know I don't have a compression gauge." See what I mean? Assumptions. OK, back to Robert:
"In part one of the formal scientific method, which is the statement of the problem, the main skill is in stating absolutely no more than you are positive you know. It is much better to enter a statement "Solve Problem: Why doesn't cycle work?" which sounds dumb but is correct than it is to enter statement "Solve Problem: What is wrong with the electrical system?" when you don't absolutely know the trouble is in the electrical system. What you should state is :Solve Problem: What is wrong with the cycle?" and then state as the first entry of Part Two: "Hypothesis Number One: The trouble is in the electrical system." You think of as many hypotheses as you can, then you design experiments to test them to see which are true and which are false.
This careful approach to the beginning questions keeps you from taking a major wrong turn which might cause you weeks of extra work or can even hang you up completely. Scientific questions often have a surface appearance of dumbness for this reason. They are asked in order to prevent dumb mistakes later on.
Part Three, that part of formal scientific method called experimentation, is sometimes thought of by romantics as all of science itself because it's the only part with much visual surface. They see lots of test tubes and bizarre equipment and people running around making discoveries. They do not see the experiment as part of a larger intellectual process and so they often confuse experiments with demonstrations, which look the same. A man conducting a gee-whiz science show with fifty thousand dollars worth of Frankenstein equipment is not doing anything scientific if he knows beforehand what the results of his efforts are going to be. A motorcycle mechanic, on the other hand, who honks the horn to see if the battery works is informally conducting a true scientific experiment. He is testing a hypothesis by putting the question to nature. The TV scientist who mutters sadly, "The experiment is a failure; we have failed to achieve what we had hoped for," is suffering mainly from a bad scriptwriter. An experiment is never a failure solely because it fails to achieve predicted results. An experiment is a failure only when it also fails adequately to test the hypothesis in question, when the data it produces don't prove anything one way or another."
-----I would like to interrupt again to illustrate that past paragraph. When wondering whether a project motorcycle has good compression, people often say to me things like "the engine blows my finger away when I put it over the spark plug hole and hit the starter button," or "it was running when I put it away," or "yeah it sounds like it has good compression." They use these "facts" to form conclusions they based off of their experiments. However, all of these are failed experiments as defined by the previous paragraph, because they have failed to test the hypothesis: The motorcycle is not running because it has poor compression. Therefore, these statements are not useful in determining the cause of the problem. Now, continuing on to the lecture...
"Skill at this point consists of using experiments that test only the hypothesis in question, nothing less, nothing more. If the horn honks, and the mechanic concludes that the whole electrical system is working, he is in deep trouble. He has reached an illogical conclusion. The honking horn only tells him that the battery and horn are working. To design an experiment properly he has to think very rigidly in terms of what directly causes what.... The horn doesn't make the cycle go. Neither does the battery, except in a very indirect way. The point at which the electrical system directly causes the engine to fire is at the spark plugs, and if you don't test here, at the output of the electrical system, you will never really know whether the failure is electrical or not.
To test properly the mechanic removes the plug and lays it against the engine so that the base around the plug is electrically grounded, kicks the starter lever and watches the spark-plug gap for a blue spark. If there isn't any he can conclude one of two things" (a) there is an electrical failure or (b) his experiment is sloppy. If he is experienced he will try it a few more times, checking connections, trying every way he can think of to get that plug to fire. Then, if he can't get it to fire, he finally concludes that a is correct, there's an electrical failure, and the experiment is over. He has proved that his hypothesis is correct.
In the final category, conclusions, skill comes in stating no more than the experiment has proved. It hasn't proved that when he fixes the electrical system the motorcycle will start. There may be other things wrong. But he does know that the motorcycle isn't going to run until the electrical system is working and he sets up the next formal question: "Solve problem: what is wrong with the electrical system?"
He then sets up hypotheses for these and tests them. By asking the right questions and choosing the right tests and drawing the right conclusions the mechanic works his way down the echelons of the motorcycle hierarchy until he has found the exact specific cause or causes of the engine failure, and then he changes them so that they no longer cause the failure."
Thanks for that Robert Pirsig. Inspiring stuff. If you are still reading this, then you probably possess the attention span and attention to detail which is required to execute this type of experiment. It's not hard at all! It's actually designed to be far easier than the alternative. It can be very frustrating to stare and frown and ponder at a motorcycle and not have any idea what to do, but if you use this method you will busy yourself with many logical and categorical steps, each of which upon completing is its own little victory, and each will bring you one step closer to finding the answer you seek.