are the engines getting stronger?

hey i am updating to a 07 wr450, atm i am riding a 99 yzf400, i was speaking a locaal bike machanic and he recons the 400's are much stronger than the new 450's, and that the new 450's need more valve adjustments i hope the 450's are as strong as my 400, i haave owned the 400 for two years and have done a fair bit of riding and recently check the valves and they are still in specs..

so is there any down sides to the new 450's????

The 450's are just as strong, if not more so. The difference is that it's more of a refined engine with a smoother pull. The '03/'04's had a pretty good kick. It was refined with the '05/'06 and then even more with the redesigned '07/'08. The power is more tractable, with a more linear pull to it, but it is by no means less than the 400. As far as valves go, unless you're racing or just flogging the bike like a madman, a re-shim is often needed after break-in and then they stay put for a long while...SC

well I don't know who that guys is or what is he thinking. The new 450 engines definitely produce more power and are lighter than previous years. I have an 06 wr 450 and I can say that it RIPS. However I have never owned a previous year 400 but I can make an assumption that the newer 450s can be a little more finicky in the mechanical department BUT are no less reliable than previous models. As for the strength, the newer engines produce more horsepower and torque so he is wrong.

hey thanks this helps, sorry wat i ment buy strength is like piston and cylinder strength, also my yz400 is 104kg wat would u normally do to make the wr lighter? and wat do u do to make it the same power as a new yzf

I've got a '98 400 and '07 450 currently. He's probably referring to the fact that the old 400's are known to be pretty strong in reliability. Steel valves -vs - titanium in the newer models. Everyone refers to the older motors as "bulletproof" reliable. Newer engines are stronger in the power dept, but maybe less forgiving if you skip some maintenance.

Either way, you'll love riding the new bike...enjoy!!!

The 450's are just as strong, if not more so. The difference is that it's more of a refined engine with a smoother pull. The '03/'04's had a pretty good kick. It was refined with the '05/'06 and then even more with the redesigned '07/'08. The power is more tractable, with a more linear pull to it, but it is by no means less than the 400. As far as valves go, unless you're racing or just flogging the bike like a madman, a re-shim is often needed after break-in and then they stay put for a long while...SC

definately the case.

he was probably saying that it would FEEL like less power because it is smoother. when something has an abrupt power-band it will feel stronger than a motor that is very smooth.

I rode my buddies YZ400, it seemed a lot quicker than my modded WR450, it was scary quick, but I dont know what he had for mods, gearing etc., my WR is way fast enough for me, love the tourqe.....

The 400's were different (over square?) in bore and stroke. 400's were bigger in diameter of bore than length of stroke thus producing a very fast revving hard hitting power curve... the 426's from what I know were square meaning bore and stroke were the same and the 450's are in a sense a stroker (not to be confused with a long stroke XR, etc...) with a longer stroke than bore. Yamaha lightened everything up to compensate and get a faster rev with the 450's but it's nothing like the earlier generation 400's.

I can and will attest to the fact that the 400's hit hard, NASTY hard in comparison to the 450's but I think the 450's pull harder in the mid range and like mentioned already have more "usable power"........

Yes the SS valves used in the earlier generations tend to last longer vs. the coated Ti valves.

I can and will attest to the fact that the 400's hit hard, NASTY hard in comparison to the 450's but I think the 450's pull harder in the mid range and like mentioned already have more "usable power"........

Yes the SS valves used in the earlier generations tend to last longer vs. the coated Ti valves.

Me too! As a '99 YZ400F owner, the new bikes feel tame in comparison. Sure they probably have more power overall, but the old 400's are monsters, they'll pull your arms out of socket and the bark when you crack the throttle is bone chilling. I've talked to a lot of riders and they will all say the 400's were stronger, or at least felt that way. They are amazingly reliable as well.

For me, I moved to primarily woods riding and it stunk in the woods, I stalled all the time and I couldn't bump start it to save my life the rear tire would just drag. I went to a YZ250F and have never looked back. I just saw a new 2008 WR250F in life, wow, almost made me change my mind on the YZ.

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