Does anyone have any info on how these two thumpers, how they perform against each other. I know the 450 puts out 55 horse, but I don't know what the 426 has, does any one else out there know. Has anyone read about a test of these two in a magazine or anything like that. I was wanting to know if the new honda motor would be able to out perform the al mighty 426. I am planning to start a 426 or 450 motor swap into a 250r frame. I was planning to start from scratch. I think a new frame from honda is like 500 bucks. Also which would be better to put the motor in the 400ex or 250r.

Thanks, Raptor man

 

the cr450 will beat a yz426. I think the 426 has "punchier" power(more like a 2 stroke, whereas the 450 is smoother putting the power to the ground. it just puts a lot to the ground. a more realistic number for the 450 is 49hp. the yz426 is around 46hp stock. I read the 450 can go 100mph with a bigger c/s sproket. this thing is a mottocross bike! it's fast. i'd go with the 450 motor, less hit(though much more than any current quad, except a modified banshee) than a 426 which is easier to drive and easier on drivetrain. I think you have to buy a complete bike to get the motor, but I may be wrong.

 

Last time at Glamis at Oldmibile hill, a 426 was smoking a 450 in drag races. By the end of the race, the 426 had a 2-3 bike length lead. I took pictures, but my camera jacked up when I wrecked, so no proof...

RoostKing...

 

I think it was dirt rider magazine that did a shootout and the 426 was an all around better bike. i don't remember about the engine if that is why but im sure they are pretty comparable but it would probably be easier to get a 426 engine off ebay or something because it has been out longer.
-Jacob-

 

I think one of the main reasons to go with the Honda is its much easier to start than the Yamaha. Good luck.

 

I am right in the middle of a YZ 426 400EX conversion.
The CR motor will be harder to get, but I think It would probably be a better option because the power is smoother, with more bottom end power, less trouble with stalling at low speed, and the wet sump design of the CR engine means one less component to mount in the frame."no oil tank"

The YZ conversion isn't that tough, you need to machine new bushings in the back of the motor for the smaller swingarm bolt of the EX, You need some kind of kickstart extension"don't have that done yet". And you need a radiator from a 250R mounted in the frame, and the oil tank moved so it will clear the radiator, and the exhaust pipe.

The worst part is finding a motor, or trying to get rid of the bike frame when you are done.

 

This is probably goin to sound stupid but, why do you have to have the oil tank with the yz426 when the yz426 motorcycle doesn't have a oil tank. I think that the reason the 426 can beat the 450 is because the yamaha has the best exhaust made for that motorcyle from the factory. If you would pipe the 450 I think it would boost the power.

 

The 450 is down on hp compared to the 426. That 55hp is measured at the crank. Yes, the 450 has less engine braking and less "hit", but definately underpowered. Word is the Honda rep that told the atv mags the 400ex had 40hp when it was first available gave the HP reading out for the 450 as well.

 

I am severely Honda biased ( hey, I'm honest at least) but would like to see a Pro caliber CRF machine before giving up on the YZF motor. The YZF's ( as well as Gusts DRZ400) ran extremely well last season on the GNC's and seemed to be an excellent race quad. Possibly the CRF will be a great motor but needs to be either destroked or debored ( easier) to be 250 class legal thus adding added cost to an already expensive project. As far as frames go sickman built a sweet 400ex based frame with a YZF426 in it and says it's an easy swap. Factory Honda frames for the 400ex are around $600.

 

The YZ is a dry sump engine, It carries most of its engine oil in a resevoir built into the frame.

One of my riding buddies has a new CR 450 F and another has a YZ 426. They are about equal in power, but the honda has more low end power and less hit. The YZ hits mucch harder and feels more like a 2 stroke but is easier to kill in the corners or other low speed situations.This is their opinion, but they know better than I.

I have ridden them , but I am not a good enough bike rider to tell you anything except they are both MUCH more powerful than my 400EX.