checking my valve clearance for the first time

7 replies to this topic
  • ratom98

Posted April 11, 2014 - 06:44 PM


i tried to dl the manual but it didn't work i must not have the right program to read it. from what i've gathered from youbute, marks on the cams should be at 90 degrees and 270 degrees facing away from each other, and the mark on the flywheel should line up with the case. all else fails just make sure the lobes are facing out. not sure what the specs are for my bike though, its a 2011 yz450f. havent had trouble starting or anything just want to check em for peace of mind

  • billygildark5007

Posted April 11, 2014 - 07:48 PM


On the newer yamahas the intake is in the front of motor. The valves will not face outward. They face inward. On tdc the intake should point around 2:00 and the exhaust around 10:00. Line up the index on the crank (the one you see threw the inspection cover) and make sure the dots on the camshaft are level with the top of the head. Then take your measurements.

  • billygildark5007

Posted April 11, 2014 - 07:51 PM


The intakes should measure .10 to .15mm and exhaust .20-.25mm

  • ratom98

Posted April 11, 2014 - 09:49 PM


cool thanks a lot

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  • ratom98

Posted April 12, 2014 - 05:08 PM


all my clearances were good, but i noticed when i took my valve cover off there were 2 chambers kind of seperate from my main valve area and they both had dirt in them, the one where the breather hose connects to had a lot of dirt in it, is that normal?

  • billygildark5007

Posted April 12, 2014 - 07:53 PM


Unfortunately yes but shouldn't be. When to engine is stopped vacuum will suck a little dirt up the bleeder hose. There are many mods here on how to reroute that hose. Just search. You could also install a one way valve in the hose. I've heard red neck stories about using one from a beach ball or air mattress and glueing it in the hose. Might also wanna check how much dirt is in your airbox and efi as this gets passed down to the intake valves.

  • ratom98

Posted April 12, 2014 - 08:15 PM


ya when i saw most of it was from where the hose connects the first thing i thought was that it needed a check valve. i will definitely look up some of the threads about it.


also i broke one of the little platic clips that holds down the plastic piece the gas tank sits on, was going to try and find a replacement clip but was wondering if i even need that platic piece? if its for heat i would think some heat tape would do a better job

  • billygildark5007

Posted April 12, 2014 - 09:18 PM


Not sure what the intended purpose of that plastic piece is but I wouldn't remove it from my bike. Maybe it helps keep dirt off the fuel pump? I don't think it's for heat but I like the idea of heat tape on that piece. Gonna do that to mine now.
Any auto store, bike shop, should have those plastic clips. Just measure the diameter of the hole they go in.

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