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CR250 trans in a CRF450R who's done it?

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I have read in the forums that a CR250 transmission will fit in a CRF450R. Has anyone done it? What year bike does the transmission need to come from? I want to install a wider ratio in my 2006 CRF450R.

Any help would be appreciated.

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I have read in the forums that a CR250 transmission will fit in a CRF450R. Has anyone done it? What year bike does the transmission need to come from? I want to install a wider ratio in my 2006 CRF450R.

Any help would be appreciated.

i have never heard.......:confused:.......the crf250r is wider ratio?.....

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Apparently some years of the CR 250 had ratios in 3rd 4th and 5th that are very close to the 450X ratios.

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Apparently some years of the CR 250 had ratios in 3rd 4th and 5th that are very close to the 450X ratios.

I believe you gentlemen have it wrong.Some time ago a member had a Baja designs wide ratio gear kit for a CR250 from when he owned a 250,Baja Designs at one time made a wide ratio kit for the 250 and another for the 450 both kits were discontinued a long time ago,as I recall he used this kit with CR250 shafts and gears in his 450.The gear ratios for stock 250 and 450 are very close and as far as I know no wide ratio solution exists for the R model be it X gears,won't fit,250 gears, no real ratio change or after market kit which no longer exists.

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In other words just ride it like you stole and don't worry about it.:confused:

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doesn't make sense to me. 2-strokes have narrower powerbands. so, don't they need shorter gears to match with that to keep the motor in the meat of the power? i've always figured that contributed to why a 5 speed 450 tops out at 90 but a 5 speed 250 2t tops out at like 65. that and the redline difference.

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no wide ratio solution exists for the R model be it X gears,won't fit,250 gears, no real ratio change or after market kit which no longer exists.

There is still one more option. The CR250 shafts with the Madman Engineering wideratio gearkit. I just called Madman the other day and he says he's just about to take delivery of another batch of gearsets which will work. This is the route I plan to go since I recently acquired an '01 250 tranny off ebay for around $50. If I get tired of the 450 I could always put the gears in my 500.

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I took a '01 250 tranny and put it in my '04 450. And yes, gears 3,4,5 are taller than the stock 450 for that year. And yes, I do notice it. And supposedly, madman is still making the wide ratio kit for the cr250 but I'm not sure. Your have to use the whole tranny from the 250, shafts and gears. The 250 had one extra shim that I had to take off to make it work in the 450. I did this last summer and it works great!

BD did make a gear kit but no more.

I too got the '01 250 tranny off ebay for like $50; sweet huh? I did replace one of the gears just cuz one cog had a chip.

So, I've done it, like it, and would be glad to help just let me know

100_0378.jpg

(can you tell I'm a little proud) This was far above anything I had done before mechanic wise so I'm just happy my bike runs again

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howdy kmpackerDMD,

The 250 had one extra shim that I had to take off to make it work in the 450.

Can you please give a little more detail about this? Like which one you left off and how you knew it wasn't needed. Did you mock it all up first and couldn't get the cases back together or did you measure the gear positions or what? As soon as I get my Madman kit I'll be putting it back together and this statement you made about the extra tranny shim a couple months back has been bugging me ever since.

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well i guess my hypothesis was wrong.

have you GPSed the 450 with the cr gears? i wonder what it tops out at now with stock gearing.

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Thank you for the information. it sounds like you used the stock gearing from the 2001 CR transmission. Do you know what those ratios are?

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well i guess my hypothesis was wrong.

have you GPSed the 450 with the cr gears? i wonder what it tops out at now with stock gearing.

The 450 engine actually spins more RPM. The CR250 motor ran about 10,500rpm and the CRF will pull 11,200.

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Hey KMD, is that a Motion Pro engine stand you got there? :confused:

Why yes, thanks for noticing. Its one of those California-esque 'git r done' stands

The extra shim was between the gears at one end and the bearing. I don't remember which one and on which end but it was obvious once I looked at the schematic. The way I noticed it was with the cases back together untightened, everything spun freely. But once I started to tighten the bolts, one of the shafts would be very difficult to turn.

The ratios, 1-5:

crf 1.8,1.47,1.235,1.05,.909

cr 1.8,1.47,1.21,1.00,.869

Its not much as stock but was easy since I was already in there for a new crank

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crap that kit costs over 700 bucks from MM engineering

:confused:

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I'm the one who did the pre-'02 CR transmission in my '02 450R. I had an IMS wide ratio gearset for an older 250 (they were all virtually the same from 86 to '01), and the whole thing dropped right in the 450R cases. I don't have the literature in front of me, but the kit included one gear for 3rd (used original CR gear on primary shaft) that made it just a little taller. 4th gear ratio was .909, and 5th was .75. Big gap between 3rd & 4th. I liked it in the desert, and was OK in the tight trees but it sucked on the track. I ran a 53-tooth rear sprocket to get a nice low 1st, but then 1st- 2nd gap was real tight, and 3rd was just about right.

I kind of remember Honda offering wide ratio gears back in '87, for both the 250 and 500. Anyone else remember that? If so, those gears might still be available somewhere.

I'm still looking for anyone who's tried making the 450x gears work in the R... I know a couple of 'em are a little wider than the R's, but it would sure be helpful to know if they can be machined down to work in the R cases, or if the R cases can be machined a little to make the X tranny work. I may give it a try in the off-season.

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I'm pretty sure machining the gears is out; they have a hardened outer that would be lost with machining. If the cases were altered and the shafts/gears fit, I'm guessing the shift drum would have to come from the X as well to account for the change in width; and maybe the shafts the shift forks ride on

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There is still one more option. The CR250 shafts with the Madman Engineering wideratio gearkit. I just called Madman the other day and he says he's just about to take delivery of another batch of gearsets which will work. This is the route I plan to go since I recently acquired an '01 250 tranny off ebay for around $50. If I get tired of the 450 I could always put the gears in my 500.

Did you get your Madman gears? How did the installation go?

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doesn't make sense to me. 2-strokes have narrower powerbands. so, don't they need shorter gears to match with that to keep the motor in the meat of the power? i've always figured that contributed to why a 5 speed 450 tops out at 90 but a 5 speed 250 2t tops out at like 65. that and the redline difference.

You are right. The 250t is geared shorter because of the 3.000 primary reduction vs. the 2.739 on the 450.

I just plugged in the numbers on a gearing calculator and at 9500rpm the 450 setup will be doing about 83mph, while the 250 setup is "only" doing 79.

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