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FJR Motorcycle Forums
Technical & Mechanical Problems
Won't start after valve adj
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<blockquote data-quote="El Toro" data-source="post: 520959" data-attributes="member: 14779"><p>One thing to keep in mind... there's nothing soft about the FJR's valves. If there were, they wouldn't hold up in the hostile environment where they operate.</p><p></p><p>We've sectioned a VFR800 in the lab as a demo so you can see the operation of the valves relative to the piston in one of the cylinders (wanted to show them how VTEC works). The clearance volume (the space above the piston at top dead center) is small. The valve timing is set up so that the intake valves actually follow the piston down in close proximity on the intake stroke, and the exhaust valves get chased by the piston as it moves up on the exhaust stroke. My point is that if you are off the mark on your cam timing by even one tooth, you can end up with interference. When you have interference, you will have bent valves. You've got mechanical advantage, sort of like a nut cracker, when the piston is at top dead center. I don't care what brand of bike you were messing with, if you got into the problem of bad valve timing, bent valves were inevitable.</p></blockquote><p></p>
[QUOTE="El Toro, post: 520959, member: 14779"] One thing to keep in mind... there's nothing soft about the FJR's valves. If there were, they wouldn't hold up in the hostile environment where they operate. We've sectioned a VFR800 in the lab as a demo so you can see the operation of the valves relative to the piston in one of the cylinders (wanted to show them how VTEC works). The clearance volume (the space above the piston at top dead center) is small. The valve timing is set up so that the intake valves actually follow the piston down in close proximity on the intake stroke, and the exhaust valves get chased by the piston as it moves up on the exhaust stroke. My point is that if you are off the mark on your cam timing by even one tooth, you can end up with interference. When you have interference, you will have bent valves. You've got mechanical advantage, sort of like a nut cracker, when the piston is at top dead center. I don't care what brand of bike you were messing with, if you got into the problem of bad valve timing, bent valves were inevitable. [/QUOTE]
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FJR Motorcycle Forums
Technical & Mechanical Problems
Won't start after valve adj
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