How ti adjust Valves in 03YZ450F?

5 replies to this topic

Posted October 16, 2010 - 02:54 PM


need to know how to do this myself have no money to pay anybody to do it.

Any and all info will be greatly appreciated, tips/ tricks awesome as well.

Basic tools? how to know their adjusted right?

Best way to do it without taking the motor off the frame? if thats possible?

  • grayracer513

Posted October 16, 2010 - 03:25 PM


You need a manual:



Posted October 16, 2010 - 03:29 PM


thanks this helps a lot

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  • grayracer513

Posted October 16, 2010 - 03:32 PM


Here's an older how-to. The process is the same, but the specs may vary since it's for an older 426:

  • Ttoks

Posted October 16, 2010 - 03:40 PM


you'll need tool's to remove the tank and seat, sockets and a ratchet or spanners, a set of allen key's, a torque wrench, a vernia caliper and a set of feeler gauges down to .01 mm thickness

take the seat and tank off, make sure the top of the engine is clean, remove the black valve cover, you'll see the cam's and valve buckets, get the engine to top dead center on the compression stroke, use the feeler gauges to measure the gap between the top of the valve bucket on each valve and the cam lobe, it's different for each bike, but for my KX250F it need's between .1-.15mm clearance, and the exhaust's are between .17-.22mm clearance, find a service manual for your bike (or ask people on here, someone will know) to find out what your bike needs, you'll know when you find the right size because it will fit, but have a little resistance and you slide it in and out, write down what the gap is for each valve

if the gap is wrong, then you'll need to remove the cams to get to the shim's which are under the buckets, then will require you remove the cam chain tensioner, then remove the cam cap/s (being careful to make sure you know which bolt came from which hole), then you'll be able to take the cam's out (i normally tie a piece of wire to the cam chain to make it easier to retrieve latter), now you'll be able to remove the bucket's, being careful not to loose the shim which is under it.

measure the shim and make sure you know what valve it came from, then it's just the case of getting the correct size shim to get the valve clearance back in spec, to do so take the shim size, add the clearance you currently have, then minus the correct clearance to that to get the correct shim size.

so say the clearance is .07mm, and you want it to be .12mm, and the shim under the valve is 3.55mm, add .07mm to get 3.62, then minus .12mm and you end up with 3.50, so you should find a 3.50 shim for that valve.

once all valve have what you believe to be the correct size shim, get the engine to the TDC cam timing mark (which is on the flywheel, again ask someone familiar with the particular bike to find out exactly how to do this) and line up the timing marks on each cam with the top of the head, put the cam cap back on, and use a torque wrench to make sure each bolt is at the right torque (this is absolutely critical, to much torque and the cams will be starved of oil and seize into the head, to little and they will rattle around and chew out the journals), once the cams are back in make sure it's at top dead center and measure the clearances again to make sure it's right, turn the engine over by hand a few times to make sure the valves aren't going to hit the piston and then button it all back up.

the two most critical factors here are getting the cam timing right, and making sure the cams caps have the right torque on them.


Posted October 17, 2010 - 07:42 AM


grayracer513 that helps a lot too ill be going between that and the Yamaha owners manual

and Ttoks thanks a lot thats a big help too ill be cross referencing all of these

im definately gonna take my time on doin it cuz i have absolutely no money to play with but i do have all the tools and have friends with all the shims etc i need

i will be posting pictures as i go juts to make sure im doing everything right

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