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Yamaha Yfz 450

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Sorry so lengthy but I have an '07 YFZ450 and i just had to replace the cam shaft and everything went well except after the installation I ran into what i thought was a timing problem but according to my repair manual it checks out....the quad will start up but it will not idle at all. As soon as i let off of throttle it dies immediately. And if i keep giving it gas i can get it into all gears but it will still die as soon as i let off the gas in any of the gears, and when doing this it gets super hot super fast. which is unlike the yfz... I am basically lost and any ideas or help would be greatly appreciated...my uncle is a mechanic and has built many 2 and 4 strokes throughout his life and he too is stumped so if anybody has any ideas it would be appreciated.

Thanks A Lot

Jake D

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Any help would be greatly appreciated...Im between a rock and a hard place

:cheers:

thanks

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Why did you have to replace the cam? I have heard of cam gears not indexed correctly on the cam. Which cam did you replace? Is the valve clearance correct?

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Im sorry I meant the crank shaft...I work out of town and I let my younger brother ride it quite often and I guess he didnt take quite good enough care of it and she locked up. My uncle is the one that did the work on it and he checked everything from a to z. He literally had it apart 3 times because he was stumped. If the timing is correct what else could it be? I guess thats my question.

THanks

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If it's been sitting for any length of time, try cleaning the carb and replacing the pilot jet. Does it want to run if the choke is on? This is a sign it's lean, and off idle lean means pilot jet. Don't try to clean the jet, just spend the $5 and put a new one in.

Also, I'd like to see what the timing looks like....can you pull the valve cover and take pix of the cams when the piston is at TDC on compression stroke? Cam lobes should be facing away from each other...

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I plan on cleaning the carb this weekend, and Ill get a new pilot jet because your right it has been sitting for several months. It will only start on full choke but it will die just the same. Ill have the picture up this weekend as well.

Thanks a lot for your time

jake

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I plan on cleaning the carb this weekend, and Ill get a new pilot jet because your right it has been sitting for several months. It will only start on full choke but it will die just the same. Ill have the picture up this weekend as well.

Thanks a lot for your time

jake

My quick bet is the pilot jet/carb.....your description definitely points in that direction. Get the pilot swapped and the carb cleaned and I'll bet your problems are overwith. Pesky pilot jets.............

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