dante Posted March 12, 2007 Report Posted March 12, 2007 I need help to help a friend. This weekend a buddy of mine has a built YFZ 450 w/ 480 kit and burns 112 octane and the local shop was out. We got smart :biggrin: and mixed 110 and 114, 1/2 and 1/2 to make 112. Sounds good right , his rings siezed to the cylinder when we were lining up yesterday. The bike was perfect before we changed the gas, plugs, and cleaned the filter. Any suggestions or comments are aprecated. Thanks. Quote
blaster668 Posted March 12, 2007 Report Posted March 12, 2007 Different fuels can require very different jetting requirements. Especially if one of the fuels is oxygenated. I highly doubt that octane caused the problem, more likely that the jetting was way off from the fuel swap. Quote
dante Posted March 12, 2007 Author Report Posted March 12, 2007 I don't agree with that because I just called Sunoco and the engineer said the fuel would have been fine, and look at the oiling system on the ATV. I just found out the bike hit something about 5 mins before the motor locked up. The driver hit a 4x4 pole and snapped it off (that could have messed up the oiling system). Or it could have been just low on oil... Quote
LiftdT4R Posted March 12, 2007 Report Posted March 12, 2007 I'm no expert on strokes or 450s, but I have heard that the older YFZs have a problem with lubrication to begin with. Check around on YFZ central a bit, some guys add what's called the oil squirter mod. I know that if you seize a 4 stroke, it's usually an oil problem. Quote
J-Madd Posted March 13, 2007 Report Posted March 13, 2007 (edited) YFZ Central Post at this forum, they can help. If he just installed the Athena 480 kit, pump gas is fine. The compression is only 12:1, I think. The oiling system does suck on the YFZs (don't get me started---two motors=two rods through the front of the case, broke away from the piston). The oiling problem is with the bottom of the piston, not necessarily the rings, unless it was very low on oil, which would be my bet. I think it's hard to get a 4-stroke lean enough to lock up, it still has lubrication, unlike a lean 2 stroke; and it would be backfiring like a mofo if it was real lean. Has the top end been taken off, or are you just assuming it was the rings? Edited March 13, 2007 by J-Madd Quote
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