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x engine into r frame?

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hi guys,

i own one 250r and one 250x (both 2009). I come from trials background and love to ride extremely hard,slippery and technical stuff. I love the way my crf 250x engine runs (air box mod, jetting and akrapovič full titanium exhaust), but many times i find it a little bit heavy and bulky for the things we ride around here.

When i ride the ''r'' version it seems much lighter and more flickable (and is 10kg lighter than ''x''), but the engine on ''r'' is just not suited for hard trials type of riding because the engine is stalling too much on slippery roots, river beds or surfaces when you ride the bike on really low rpms searching for traction.

So my question is: is it possible to put the ''x'' engine into ''r'' frame? what mods should be done?

Or to make it easier, which parts should i put into ''r'' engine to make it run like ''x'' version? (flywheel, gearbox, ignition..?)

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Put an "X" cam in your "R" and get a heavier flywheel, that should make it much more friendly type the riding you do, no need to change the entire engine, they are very similar and the manners of your "R" model cam be tamed down..

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Get a good after market heavey flywheel as that will help alot with stalling.And easy to do,but will have to buy a fly puller that has a spacer that sits over the crank or will damage the oil way:ride:Ebay job £20

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Get a Rekluse as well, put it on the R w/ the heavier fly wheel weight!! That Rekluse will help you get thru all the tight, nasty, slick, rocky, rooty stuff!!! Hands down, its the way to go for the "extreme enduro" type riding!!

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IMO the main issue with trying to use your R in the tough, slow speed technical stuff is the fact that stock gearing is too high to be able to use a smooth, low rpm pull from the engine. There is a significant difference between the first gear overall ratios of these two bikes and thats a key difference between track and tough trail riding. Theres also a power difference but that wouldnt be as much as a problem as the gearing difference.

You could probably improve it by putting more final drive gear in it like 13-53 to slow down first gear but thats going to have a big affect on the rest of the gears also. But if cost and availability wasnt a issue to be able regear the primary and/or just the first gear trans ratio would make a big differece and make it more adaptable for that type of riding.

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18 " Rear Wheel of the X makes a big difference too....the X is a Billy Goat on steroids. I love it !!!

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Check this forum for things you can remove to make the x lighter. battery, kickstand, swap the stock exhaust can for an 04-05 R silencer, one guy even removed the starter (required machining spacers to remove the starter clutch gear and plug and bracket to seal the eng),

I am pretty sure the X eng will not bolt into an R frame without modifying the eng mounts.

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Check this forum for things you can remove to make the x lighter. battery, kickstand, swap the stock exhaust can for an 04-05 R silencer, one guy even removed the starter (required machining spacers to remove the starter clutch gear and plug and bracket to seal the eng),

I am pretty sure the X eng will not bolt into an R frame without modifying the eng mounts.

The cases are the same,will fall straight in.Tbh that is the last thing you should do.For trails i would have to have starter,and a stand.Seems crazy to take of the parts that your gonna need for trails:banghead:

All them posts,take it you ride a yamaha not a red devil:smirk:

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I am pretty sure the X eng will not bolt into an R frame without modifying the eng mounts.

Actually the engines will swap between the R&X frames, direct bolt in with no mods.

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Actually the engines will swap between the R&X frames, direct bolt in with no mods.

Are you sure? Have you switched one??

People are saying yes and no, which one is it?!:bonk:

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Are you sure? Have you switched one??

Yes I have done more than one. 04-09R = all year model X

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The cases are the same,will fall straight in.Tbh that is the last thing you should do.For trails i would have to have starter,and a stand.Seems crazy to take of the parts that your gonna need for trails:banghead:

All them posts,take it you ride a yamaha not a red devil:smirk:

Actually mine is an 06, still has stand starter and batt.

garage.php?do=viewattachment&attachmentid=58670&thumb=1

and yes it does get ridden/dirty

garage.php?do=viewattachment&attachmentid=61685&thumb=1

It does not get ridden as much since I got a Gasgas 300.

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Well color me wrong, but I read on this forum that the R and X had different frames (parts fiche verifies this) and part of that was different eng mounting. Never would I give up the trail items the X has for the extra HP the of the R. I never even considered swapping engs.

And as for the weight savings removal of parts, I was just pointing out the stuff other folks have done.

ANd one I forget...e-batt saves a couple of pounds and you get to keep the starter.

And there have been more than one rider who went to great lengths to mount R plastics on their X's...go figure!

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I have a stripped x bike off everything,turned it close as poss to a r version.But i only ride mx tracks:ride:

Me if i was doing trails id prob go for a ktm like most people seem to:smirk:Some of the trails you guys seem to ride are bloody tight and twisty really slow stuff.Id want something super light and chuckable.I just cant ride 2 smokes well:banghead:

P.s try giveing that bike a wash:smirk:

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put an "x" cam in your "r" and get a heavier flywheel, that should make it much more friendly type the riding you do, no need to change the entire engine, they are very similar and the manners of your "r" model cam be tamed down..

++++1

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I have a stripped x bike off everything,turned it close as poss to a r version.But i only ride mx tracks:ride:

Me if i was doing trails id prob go for a ktm like most people seem to:smirk:Some of the trails you guys seem to ride are bloody tight and twisty really slow stuff.Id want something super light and chuckable.I just cant ride 2 smokes well:banghead:

P.s try giveing that bike a wash:smirk:

Hey brotha, I meant to ask you, why get an X and go thru all those mods and switching of plastic, removal of starter, etc, if you just wanna ride it on an mx track?? Why not get an R, ready to go, light, and can only get faster and lighter?! I can see making mx bikes into woods bikes, but why make a woods bike onto an mx bike?! :smirk:

As slow, heavy and weak as everyone claims these bikes to be, why use it for the track?!!:bonk:

I'm just curious my friend!!!

All my mx bikes I've set up for the woods, but my 1st and only woods bike, I'm gonna set it up more for the woods:thumbsup:

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Got the bike cheap fella, and at the time i thought it was just a r version with lights and starter:bonk:As ive done all the work myself its worked out not costing that much money tbh.Plus its mint like a new bike.Im never gonna be the fastest guy on the track but i can keep with alot of peolpe.I go rideing with 450r,tm125,quadzilla450,kxf250.Round 90% of the tracks we ride im quickest of them all:smirk:Just the long straights the 450 gone:bonk:There are alot of super fast 125cc kids at one track we ride on,and they kill everyone on track:ride:You can have the best setup with loads of engine mods but if your sh.t then even the quick small bikes will be on ur ass:bonk:

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