BlueRapted
Ragley,La
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Joined: 12/14/2007
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The Dirtbike just has different gearing,more aggressive cam,and just a few other minor stuff.But in the end they are the same motor with different tweaks.
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blasterfan84
lindsay On
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Joined: 06/17/2006
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i can guaruntee you you put both motors on a dyno and the crf is faster, and the CRF has EFI, the 450 doesnt, the new yami bike has a whole new motor.
and even if the motors are close, the dirtbikes are alot higher strung than teh quads, making much more HP, thats all im saying here
09 450SX, fourwerx seat,, hipers, akro Slipon, race techs, fourwerx hood, cycra handguards, wiseco 12.5:1 piston, FCI intake, and some other goodies
2010 Sponsors, KTM Canada,HB Cycle,Race Toyota, Parts Canada ,Motovan,Fourwerx Carbon, smith optics
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BlueRapted
Ragley,La
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The reason they are putting down more hp is: more aggessive cams,lighter flywheel,better flowing exhaust,and less restrictive intake.Nobody is arguing wich is faster but the are equally "high strung".
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camo fox
wisconsin
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Joined: 12/13/2007
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you also can put into count the tire size. A DB tire is 2x's as tall as a quad tire, not to mention sprockets.
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YOURADHERE
Louisiana
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Joined: 07/28/2006
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I just got around to reading this thread so excuse my tardiness.
Ive said for a long time that a 450 is not for everyone, yet you continue to see an ever growing number of them EVERYWHERE. I'd say that probably a large majority of 450 owners a) dont truely need one or b) are unaware of just how much a ticking time bomb they can be. And since alot of them are more track/race oriented their suspension setups are typically too harsh for the average everyday rider. If I were to EVER pickup a 450 it would be because a) I got it cheap(read: likely already broken) and b) I fully intend on going through the motor top to bottom and replacing needed parts, gaskets, bearings, piston, rings, etc etc. Even still I say I'd likely build something like a 250r before I ever own a 450.
07 z400-Yoshimura R3 full system,Uni filter,White Brothers CDI,Hydrodynamic +2 ST A Arms,G Force +2 axle,TCS Shocks w/remote rezzies,PEP stabilizer,RazrMXrears on ITP T9s, KendaMX fronts, Skat Trak 7paddle Haulers on Douglas .125s....I need more sig room
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YOURADHERE
Louisiana
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blasterfan84 wrote:i can guaruntee you you put both motors on a dyno and the crf is faster, and the CRF has EFI, the 450 doesnt, the new yami bike has a whole new motor.
and even if the motors are close, the dirtbikes are alot higher strung than teh quads, making much more HP, thats all im saying here
It should also be noted going back to the different cam profiles crap, that a common swap on the KFX450 is to get STOCK KX450F cams.
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bbqmaster
KUNSAN AB ROK
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Joined: 04/11/2007
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its not as expensive as they are making it out to be to rebuild a 450 MX motor
yes they have to have a top end about every 12-20 hours i would say 15 hours to be safe.
the reason look how short the skirt is on the piston and how high the cr's are on them 12 and 13:1 and they rev to the moon faster than you can blink..
with regular maint. with a top end rebiuld keeping valves in check replae titanium valves with stainless steel(lose a little performance gain some reliablity back) and keep everythign in spec you shouldnt have any MAJOR problems for a long time and depending on how brutal you are on the clutch prob have to be replaced each riding season..... but yea if you wait untill you hear funny noise coming from the motor and take it to the stealership yea your gonna pay 3000+ for that rebuild
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BlueRapted
Ragley,La
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The point was the parts are very high to replace,like piston or rings plus gaskets and etc.. Also if you are not a mechanic the labor is gonna cost you alot also to do those routine jobs.
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rad valve
In the woods
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What I don't under stand is why dose one motorcycle piston cost as much as 8 small block chevy pistons.
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bbqmaster
KUNSAN AB ROK
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2002 crf450r.....PK1365 $294.28 96.00mm STD Compression Ratio - Actual: 12:1
Displacement: 450cc
Stroke: 62.1mm
2002 cr250r........PK1195 $229.47 66.40mm STD Displacement: 249cc
Stroke: 72.00mm
Notes: Pro-Lite, Nikasil Bore
1990 cr500r........PK1486 $272.87 89.00mm STD Cylinders: 1
Displacement: 491cc
Stroke: 79.00mm
Notes: Pro-Lite
thats not that much dif in the prices if you know how to do your own work
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