09, 450 valve clearance.

That feature is called a "quieting ramp", and it is indeed an important feature. Some aftermarket cams don't dedicate as much effort to it as the OEM's do, either.

Wouldn't surprise me. They sell cams based on torque/hp curves being an improvement over OEM, so not telling people of the slight side effect that their cams may cause accelerated valve wear is not something they would openly publicise!

As far as the Honda Valve issue goes, I had an '02 CRF 450R with 126 hours and the valves never needed adjustment. The next bike I had was an '05 CRF 450R and the OEM intakes crapped out at 55 hours.

I didn't change my maintenance schedule, I didn't change where/how I was riding, I didn't change air filter oil brands etc. etc. I did everything the same, but the valves lasted less than half as long.

I can't explain why my '02 lasted and my '05 didn't, but in my case maintenance (or lack thereof) wasn't an issue. By the way, Honda changed the valve seat material in '06 in an effort to extend valve wear life.

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