Chain rattle-slapping skid plate? - Yamaha ATV Forum
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post #1 of 2 Old 12-18-2016, 12:08 PM Thread Starter
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Chain rattle-slapping skid plate?

Just picked up an 08 yfz450, and when riding, esp. When decelerating you can hear loud rattle, and the chain seems to be resting on the chain guard skid plate. Any ideas on how to fix this? Looks like its digging into the plate, not sure if I just need to adjust chain tension or what. Any help would be great thanks
Jmward2008 is offline  
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post #2 of 2 Old 12-19-2016, 03:04 PM
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sounds like the tension is too loose and you need to inspect it and adjust it. lift the machine so all four wheels are off of the ground. lift it by the frame not the suspension. the suspension has to be completely unloaded. there is a little flat raised spot in the middle of the swing arm. hook a tape measure on the bottom of that and measure the chain slack. line one finger up with the tape measurs on the chain and push it down as far as it will go write that measurement down. using one finger lift the chain as high as it will go and write that measurement down. subtract the first from the second it needs to be between 1 and 1.25 inches. (i run in sand only and use 1.5 inches to prevent binding but that is out of the factory recommendations so use at you own risk) if it is more you need to tighten the chain. if it needs tightened you will need to inspect the sprockets and the chain itself. the teeth should be even and flat on top, if they are hooked or sharp you will need to replace them. look for wear on the chain. it should move freely with some side to side flexibility but not too much. just behind the adjuster nuts on the swing arm is a set of lines you should be in the middle of the adjustment range if not your chain needs replaced. to adjust the chain loosen the 17 mm axle bolts and the jamb nuts on the adjuster bolts. lengthen the adjuster bolts until the earlier measurement is in spec and tighten everything up. hints: loosen everything up, shove the axle all the way forward and snug the axle nuts. run the adjuster nuts all the way in and use a sharpie to mark one flat side of the bolt. it is critical that not only the chain slack is correct but the length of both adjuster bolts is the same. by marking one flat side you can turn each bolt the same number of turns keeping it even. when it all looks good tighten everything up, i use a small droop of blue locktite on the jamb nuts but that is optional. dont use the red. if you have a flair nut end wrench use it on the jamb nuts to keep from rounding them. if you could add a picture i could give more specific advice. this will work for you if nothing else is wrong
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