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cb1862003

wr450 motor in 03 YZ450 frame?

14 posts in this topic

does anyone know if a WR450 motor will fit into a 03 YZ450 frame? i occasionally road race my YZ, and am looking to get some more top speed out of it. the frames have different part #'s, but figure that it may just be some small differences (i hope).

Thanks, Chad.

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save your self the trouble. just buy a pipe or get your head ported

I believe the WR has a taller 5th gear... actually the 03' YZ only has 4 gears I believe, while the WR has 5.

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I believe the WR has a taller 5th gear... actually the 03' YZ only has 4 gears I believe, while the WR has 5.

correct. i need a taller top gear. i am currently running a 16 front, 38 rear gear set up. i think i am in the 115mph range, but need more. with a swingarm mod, i will be able to get a 35t on the rear, but that woun't be sufficient.

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wow it seems like it'd be easier to put your YZ suspenders and such on the WR.... or something..

where you running that you need such top end, road america??

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You want to go more than 115mph on a dirtbike?! :applause: I could never do that. When I rode my friends YZ250, it had 15 and 48 gearing and tapped out in 5th gear is about as fast as I would ever care to go on a dirtbike. If you want more speed why not just get a 500? I know its not a thumper, but it would definately have all the power you need. There is always the idea of a KTM 525EXC motor. Those have a 6 speed.

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oh 5th gear well that makes sense but i still dont think that would be worth the effort of buying a wr 450 motor and switching it and blah blah but if you really wanna do it and it fits go for it

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Doesn't the complete tranny from the WR fit right in the YZ? I think if you look back you'll find a couple threads on it.

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You want to go more than 115mph on a dirtbike?! :applause: I could never do that. When I rode my friends YZ250, it had 15 and 48 gearing and tapped out in 5th gear is about as fast as I would ever care to go on a dirtbike. If you want more speed why not just get a 500? I know its not a thumper, but it would definately have all the power you need. There is always the idea of a KTM 525EXC motor. Those have a 6 speed.

i already have a yz450. i want to built a 490 for it, but it has to be capable of higher top end, thusly, the wide ratio of the WR.

Mid America Motorplex is where i was racing. i was grabbing 4th gear about 100yards out of the last turn, and was looking for another gear by the flag stand. i am guessing that another gear will gain me another 15mph pretty easily. my goal is to run with the top 3 or 4 in the LW class(SV's).

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Doesn't the complete tranny from the WR fit right in the YZ? I think if you look back you'll find a couple threads on it.

hmmmm, maybe. i figured the cases where different, so the tranny internals would be too.

i actually want 2 motors for the bike. one for roadracing that is a 5speed and built up a bit. a second that is basically stock and that i use for ice racing, flattracking supermotard and dirtbiking.

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What you can do for about $700 is to put the complete WR450 transmission into your YZ cases. It bolts straight in, but you need the WHOLE thing, including the shift forks and shift cam.

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What you can do for about $700 is to put the complete WR450 transmission into your YZ cases. It bolts straight in, but you need the WHOLE thing, including the shift forks and shift cam.

Thanks, maybe thats what i'll do then.

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Be very careful with sustained high rpms with your YZ 450....Thats what killed my cam bearings on mine...(1/4 mile short tracks) Check the clearance at the cam bearing...

BC

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Be very careful with sustained high rpms with your YZ 450....Thats what killed my cam bearings on mine...(1/4 mile short tracks) Check the clearance at the cam bearing...

BC

i'll keep an eye on them.

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