03 YZ 450F intake valve stuck?

8 replies to this topic
  • Matthew12815

Posted March 08, 2015 - 09:45 AM


Alright, I can say I am truly stumped. and I am asking for help. I have an 03 Yz 450F and the rear intake valve is stuck and it can't go down(with the spring on). it is the intake valve that is closest to the kick-starter. But when I take the spring out the valve moves freely( pretty much no resistance). the valve cap/ bucket has no scrape marks on it(so it's not rubbing). Can anyone help me? They are also new valves the head just came back from a shop(got the guide reamed out). I also checked the valve and it is not bent. Any help?

  • Krannie McKranface

Posted March 08, 2015 - 10:07 AM


Sounds like there is too much tolerance in the guide and the valve is rocking in the guide?

  • Matthew12815

Posted March 08, 2015 - 10:43 AM


So I would need to get a new guide, seal's all that stuff again?

  • Krannie McKranface

Posted March 08, 2015 - 04:29 PM


You said they reamed the guide. Why did they not replace it?

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  • KPRacing

Posted March 09, 2015 - 08:20 PM


When you say, "cannot go dow." Do you mean the valve will not open or the valve is held open?

  • KPRacing

Posted March 09, 2015 - 08:29 PM


If the valve will NOT open, the guide may not be totally seated causing the valve spring retainer to hit the guide & stopping the valve from opening.

If the valve is held open with the bucket in place, the bucket could have been damaged while the motor was apart. Possibly stepped on or something to deform it causing it to be somewhat crushed (oval shaped) which could cause the valve to stick. But this would only be the case if the bucket does NOT slide freely in the pocket.

  • Matthew12815

Posted March 12, 2015 - 05:19 AM


The valve bucket slides freely so that's not the case. I can take it off with no problem. But when I put it on and try to push down on it, it wont even budge. I've tried tapping it with a hammer and a wooden stick( put together) and that wont even budge it. I have it booked to go back to the shop I got it from later next week. unless I figure it out by than.

  • KPRacing

Posted March 12, 2015 - 10:29 AM


So it won't OPEN. Check the valve guide. See if it is fully seated.

  • Matthew12815

Posted March 14, 2015 - 05:23 PM


ok will do.

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