Valve adjustment for 2006 WR 450

Hey guys, a little help from those that have been there already. I have 5 questions. Please respond to 1 or all, Thanks.

#1 My 2006 WR 450f Manuel states that the exhaust valves are to be .20 to .25mm and mine are exactly .20mm. My intakes are said to be .10 to .15mm and my outside valves are exactly .10mm and my middle valve is .08mm. Is this difference something I need to fix right of way (the mechanic at my local shop said it is no big deal!?) or do I just ride it as is?

#2 Another question is how much difference in the way it runs by being at the least of the tolerances vs. the greatest of the tolerances? In other words, would I get better performance with the intake valves being .15mm and the exhaust being .25mm. Which is better?

#3 How much difference does the BOYESEN QUICK SHOT Accelerator Pump Cover make for trail riding?

#4 Is the investment in YZ cams worth much or not? My riding is trails and fire roads mostly and some track. I do ride hard and use most of the bikes power. :devil:

#5 Toothing down on my sprocket for better low end is good idea or not according to most of you guys who have my style of riding?

Thanks, Jason


Quick shot did help but was done while the jetting was done as well as the rest of the mods.

I really liked messing with gearing to achieve goals really cheap. Get a 13 counter and try it out-I really liked it in tight conditions.


#1, get your valves adjusted, too tight will lead to expensive head work/valve replacement. DO IT SOON!!!!

#2with valves at the very loose end of specs you might loose a touch of power, but not much

#3 boyesen is great, love it on my WR for trails ect. well worth the 90 bucks you spend on it.

#4, don't bother, not worth it to me, but some other people who have done the swap may have more input.

#5 try it and see, front sprockets are only 15 bucks. I am plus two on the rear, but thinking about going to stock after adding a pipe.

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