YZ 426 valve issues?

7 replies to this topic
  • HotRod250F

Posted September 15, 2004 - 08:13 PM


Has anyone ever had any valve issues/concerns on '00-'02 426's? I'm thinking of going back to a big bore (sold my 250F) and I'm considering going to the "dark side" (Honda 450) but I'm not sure because of all the valve concerns I've read about in the Red Forum. I'm a little leary to go Red. I had an '01 YZ 426 that was rock solid reliable. In nearly two years I had it I never had valve issues, never needed adjustment, nothing. The bike started 1-3 kicks when cold and 1 kick when warm, guaranteed everytime. It was a great bike. I'm narrowing it down to YZ 426 vs. CRF450. Since I never had any valve problems with my trusty '01, does anybody else have any valve horror stories on their four-two-six?? Lets hear it.

  • 426_Texan

Posted September 15, 2004 - 09:06 PM


Are the CRF450s having valve problems too?
I thought it was just the 250s

Anyway...no valve problems with my 00 426

  • YZ426FPilot

Posted September 15, 2004 - 09:37 PM


Checked but never touched. Always remained on the tight side of spec.

  • Hamish

Posted September 16, 2004 - 02:43 AM


my 426 is almost due for a centre inlet. It looses about 0.05mm every 80 litres of fuel, so I'd say the coating has worn off that valve. Seems better now I run motorex valveguard in the fuel. It has about 7000KM on it that I know of, plus whatever the previous owner did with the odo disconnected. Also you never know how often the previous owner cleaned the air filter. I'm not complaining, it's a great bike. If you have to do a few valves every few years so be it. Thats the price we pay for high performance engines. I'd never leave blue, wouldnt mind a 250F though :thumbsup:

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  • sirthumpalot

Posted September 16, 2004 - 02:49 AM


The big YZFs have been great in the valve department from what I read here. I've got the 01' myself and so far no adjustments required.


Posted September 16, 2004 - 07:04 AM


I have has the engine apart on my 02 426 three times for various mods and upgrades. The valves have only required shims on a couple of occaisions, after the end of the first year...They were just a little tight and when I put the Hot Cam's in because of the greater lift of the cams. Other than that they have been perfect.

Bonzai :thumbsup:

  • Ga426owner

Posted September 16, 2004 - 07:15 AM


Yamaha's do not suffer from the same valve issues that the honda's have. Thank goodness.

  • cowboyona426

Posted September 16, 2004 - 09:25 AM


I've never heard of anyone having problems with the valves in their blue thumper. I've never had a lick of trouble with my bike.

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