2008 wr valve question

3 replies to this topic
  • casper36092

Posted September 16, 2010 - 06:45 PM


i have had my bike for about a year and bought it used with a little time on it. i race the bike in hare scrambles and enduros in the a class. this weekend at and enduro my bike cut off a couple times at a few restarts. but would run fine and start right back up as long as i was not sitting there idling.

tonight i checked my valves and the 2 outside intakes are a very tight .10 and the middle one i could force the .13 in but could not move it. the exhaust valve check out good though. i never checked them before so idk if they have moved or not so my question is should i worry with them or just keep riding.
a friend of mine told me on the yamahas you need to replace them instead of adjusting because the intakes are so small so that will make it suck a valve quicker if you let it wear to much.

thanks chris

  • GuyGraham

Posted September 16, 2010 - 10:30 PM


well if the intakes are 0.1 then they are in tol
Spec is 0.10 - 0.15mm, so you are good to go

Tight valves manifest themselves as starting issues, not cutting out issues

try turning the idle up a little
Also, what gearing you using?
When I had a 14T tooth front (with 50T rear) I had stalling issues in the corners
dropping to a 13T front really helped

it's true, that when modern valves do start to move then they will need replacing, as the hard coating has worn off (hence why they are now moving), but yamaha's are no diff to suzuki's or hondas or kwack's in that respect

Edited by GuyGraham, September 17, 2010 - 11:26 AM.

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  • casper36092

Posted September 17, 2010 - 07:20 AM


well it restarted fine this was just while sitting on the line it kinda flamed out. the race was real tight that day so the motor was pretty hot. my only prob is that i havn't ever checked the valves so idk if they are moving or if they where that spec from the factory.

  • GuyGraham

Posted September 17, 2010 - 11:28 AM


Yamaha seem to like them to be towards the close end of the tol any way

My 450 has 2 intakes at 0.10 & 1 at 0.11

Don't worry - just ride it

Check 'em again in a 5 hours of use - if they are moving they'll have moved again by this time


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