WR450F Max hours on engine?

i see what you guys are saying and i understand it all...and 350 hours seems like a more realistic number for the piston to wear out..some of the people that claim 1000 hours on a top end are either babying there bike so much its almost idling the whole time or its not a real number...cuz that sounds way too crazy for me. and its not really where each bike is used because a yz450f trail ridden last about 150 hrs..

and GuyGraham you said you replated your bore, did your bore get scored or something?

No, as it was apart I decided to refresh it completely and do a proper job of it


That's just me though, its was plenty good enough just to put a new piston and rings in and probably would have gone another 300 hours

Edited by GuyGraham

did the rings look fairly well worn? and did it feel alot snappier and fresh once it had a new top end


I used to be a Honda guy until they came out with the CRF's too many valve problems. Yamaha was smart and tempted when everyone said they should just take one of their awesome very reliable street bike motors cut it into a quarter and shove it into a MX frame.  Walla the YZ400 concept was borne.


I switched to Yamaha's. However I still own a XR250/300 and a CRF230/250 based bikes. The 1996 up XR250's have intake valve problems however I had a cam made with the same lift and more duration concentrating on good opening and closing ramps that seemed to correct the problem.

Well how many hours,I say the Wr450 is not a hour bike,Its a years bike.Got my 07 new first month had 40 hours on it.Trail rode not raced 90% dirt.First valve adj,Feb 2014,this bike rode almost every week.07-feb 14.Because I sold it got a 11Wr. The old bike did not use oil or smoke.Stevethe knows this bike.As far as I know still going strong,it has lasted every bit as long as my Xr440s.The only thing is it would cost way more to rebuild it then the xr.Great bike  BTR

Ive 17000kms on mine and only ever done vales

635 hours on piston and rings #4 head #2, rings #5



Edited by KRANNIE

My 06 is hitting 17000km, I brought it at 9800km and I'm sure nothing has been touched except for the usual mods....

I've just started to replace all the external bearings and freshening up the plastics with plans to do the top end later this year..... It's my everyday rider

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