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grayracer513 last won the day on December 2 2008

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  1. Let's not panic, shall we? With regard to the valve train, the scattered head was the result of one valve breaking, which is usually the result of running a valve that has too much wear on it for too long. How much is too much? A valve that needs shim more than .10 mm smaller than it had when it was new has worn through the hard coat and needs replacement. Check your clearance and your service records. Back to the symptoms. If the bike is stalling when you chop the throttle under a fairly good load at lower RPM, the usual cause is the idle set too rich. Especially with a Rekluse. Idle should be set at least lean enough to pop on decel "some of the time". This keeps the engine from falling back to idle so fast that it drops below idle and stalls instead. Remember that the main cause of "hanging" idle (doesn't idle down soon enough) is a too lean setting? That's why this works. Do a leak down, check your clearance, yes. But try trimming the idle, too.
  2. Not very much more than otherwise. I got my Cycras after stuffing the bars in the dirt and having the clutch lever mash my ring finger once too often. An added benefit is that I actually was able to wear out a pair of grips before I tore the ends off of them.
  3. The book will say you need 95 octane, but that's Research Octane. That's about the same resistance to detonation as 86-87 Motor Octane. Different methods of testing that produce different numbers. Here in the US, the government tries to simplify things (and you see how well that works) by using an average of both methods called the Anti-Knock Index (AKI), which comes out to about 90, so 91 octane at the pump is fine, even on paper. In reality, almost no one has a problem with ordinary pump premium in a stock YZ450.
  4. For the copper concern, run another sample at the same approximate mileage to see if it levels out. I'm not familiar with the 690, but browsing a little, it doesn't appear to have side washers or a small end bushing on the rod, so the copper could really be coming from the clutch plates, depending on the composition of the linings. I'd like to know from a KTM pro what sources of copper there are in that engine, and what the linings are like. As for leaching, that happens, but not at that rapid a rate unless there's a lot of copper exposed to the oil. I would doubt that had much to do with it. There are any number of could be's, like a pile of copper deposited early on that continues to avoid being filtered, or maybe even circulating, but sits near enough the drain to show up in a sample. Another sample down the road will help give you a clearer picture. The viscosity loss is due to gearbox shear, more than likely, and you should either find an oil that holds up better or shorten the oil change interval. The good news is that it didn't do that badly; it's still at SAE 40, albeit the low side, and 40 is really enough for most things.
  5. Seeing this suggested something to me. It sounds like you may be experiencing the numbness either because of nerve compression as Bryan says, or from a reduction in circulation as a result of a continuous too-hard grip on the throttle, much the same kind of thing that brings about arm pump. I'm subject to right hand numbness on long road rides. Whereas I can drop my left hand pretty much at will, the right has a full time job, and will tingle after a time. What I do is to relax half the hand at a time, gripping the throttle with the index finger and thumb for a while, then switching to gripping with the other 3 fingers and relaxing the first set. That may not be practicable off Road, but you might find that anything that helps you loosen up your right hand for as long as possible may help, be it suspension tweaks, riding style adjustments, strength training, or just practice and confidence.
  6. Simple. Through practice and experience, you train your right wrist not to be influenced by the tugging of the bars, and to manage the throttle independently of steering control. No magic to it.
  7. If the piston is stuck, how would an impact wrench spin the crank? Take the clutch off. Remove the nut. Done. If you can get the cylinder off, do that and hold the rod with a glove. Jamming the gears with anything metallic is a bad idea that can cause chipped teeth.
  8. Most often this happens because of a faulty timing chain. Sometimes the tensioner, but usually the chain. If you find several stiff links in it, that's probably it. Change them both on the way back together. Don't even consider reusing the center valve. You have a couple of options. One is to grind on the stem tip until it will pass through the guide (then hope that you can get the head cleaned out) or see if you can open the valve far enough to cut the valve head off and back it out the top. In all likelihood, you will need all three intake guides replaced anyway. The piston that did this should also be replaced, and it would be a smart move to pull the crank and have its alignment checked.
  9. To measure wear on the chain, use a standard 6" vernier caliper. Wedge a wood dowel or tool handle under the chain at the rear sprocket and draw it tight so there's no slack. Measure multiple sections of chain between 11 rollers as shown by "a" in the picture. A new chain will measure 5.85". When it gets to 6.0", it's 2% longer than new due to wear at the pins and the bushings. You should definitely replace it at that point (I use 1.5% as my personal limit). A worn chain is what wears out sprockets, not the other way around.
  10. The first couple of sentences basically just restate what I said. Pre-ignition is caused by any condition that ignites the fuel prior to the intended ignition point. However, while you may not use the word "detonation", that is precisely what "knock" is. "Knock" is the lay term for the audible sound fuel makes as it detonates, rather than burns. Pre-ignition causes it for the same reason that too much spark advance does. The earlier in the burn the detonation happens, the worse it is because more fuel is involved. Your "mega-knock" condition is simply that; detonation occurring very early on in the burn so that it involves a larger portion of the fuel charge. Detonation events have been known to produce dramatic, even spectacular failures, bending connecting rods, breaking pistons and cranks, and blowing whole cylinders off engines. It is often worse on supercharged engines since the whole idea of supercharging by any means is to force the engine to process a larger quantity of fuel.
  11. The Cause of "Arm Pump"
  12. Actually, you can put the filter in backward IF the bike has an aftermarket oil filter cover with a letter "R" on it. The OEM cover has a tab built on that extend through the output hole in the end of the filter. The Ready Racing filter cover does not, so the filter can be reversed. The hole in the end of the filter goes outward toward the cover. Having said all that, it is extremely doubtful that you rode the bike 5 hours without oil circulation. More than extremely. It's a dry sump system, and oil feeds from the tank, into the engine, drains to the sump, and gets sent back by way of the external oil line that runs up the left side of the frame. If you run the bike with the oil cap off, you'll see oil being returned just under the filler cap on that model. A steady stream after a cold start, then once the return pump catches up and clears the sump, it will become irregular and in spurts; the return pump outruns the feed by design. The oil in the tank looks cleaner because you're looking at the top of it instead of the dregs.
  13. Yup. Worn gear dogs on the 5th and 3rd pinions (gears on the main shaft) and the center shift fork. Under power, the gears "climb over" each other, which bends and wears the fork.
  14. You'll need a flywheel puller (don't be tempted to try to use anything but the right one for the engine; they're $20 or less) and a torque wrench capable of accurately applying 6.5 (75 inch pounds) and working around the frame top tube. And a service manual With reasonable mechanical skills, it should take about two hours, and less than $100 in total parts. First, you want to check to see if the timing's off, of course, but it's likely that it needs a timing chain if you don't know when it was replaced last.
  15. If you're not above changing the fork out at the steering head, clamps and all, the head bearings have been the same since '97. Just about anything from 2000 onward can be put onto the frame that way. The newer steering head is a little shorter, but only 5mm or so, and an extra washer will solve that problem. Good a way as any to make sure you keep up on your bearing maintenance.