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Suggestions on how to get R type power out of my X

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Would like to keep it legal(California).

My list so far:

White bros XCR, FMF power bomb.

Twin Air power flow, Cut air box.

Jetted carb, smog pump retained, crankcase vented to atmosphere.

What I would like to do:

Athena 280 kit, with HC piston.

R or stage 1 hot cams. but which year r should I use or a stage 2 maybe?

port my 06 x head, would like to keep my 06, but are the new heads better?

or should i just find a used r motor and swap an x head onto it?

Thanks for your help guys, Alan.

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Heres what I did.06 R headed ported,stage 1 H/C,High compression 13.5.1 piston R pipe stock header and all the CCC mods.That probably put me close to right about 35 hp.Not a big fan of Big bores.

No matter what you do engine wise the X will never feel as punchy as the R with the wide ratio tranny and a heavier fly wheel.You can change the Fly wheel though.

If you want to keep your AIS system just port your head and run a highcompression piston and new cam.

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Your 06 x head has the old style intake port the 07 x head with smog has the 07 crf intake port .although i dont like the smaller stem on the exhaust side of the 08 crf head they seem to beholding up well im having components made now to except the smaller stem valve .the 08 head in stock form is very good with its reduced port volume the 07 head is a better head for a start on a all out race engine .I am going to start machining the 08 heads for the smog to be used on an x .you could also update to the 08 r cam.

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Your 06 x head has the old style intake port the 07 x head with smog has the 07 crf intake port .although i dont like the smaller stem on the exhaust side of the 08 crf head they seem to beholding up well im having components made now to except the smaller stem valve .the 08 head in stock form is very good with its reduced port volume the 07 head is a better head for a start on a all out race engine .I am going to start machining the 08 heads for the smog to be used on an x .you could also update to the 08 r cam.

Could you pm me or post a price on a complete '08 head modified for smog? Would you suggest a port job on that same head for my motor? Very interested as I would just put an R motor in it but I heard the rangers tend to check for smog stuff during the summer here in California.

I'm trying to track down an R cam now.

Much difference between 06, 07 and 08 cams?

Thanks for the help, Alan.

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http://rickramsey.net/CRF250X.htm

My favorite 250X website: clicking will cause a chasm to open below your chair followed by your immediate tumble into the 250X abyss never to get out alive (both good & bad...) Click & you'll see what I mean.

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http://rickramsey.net/CRF250X.htm

My favorite 250X website: clicking will cause a chasm to open below your chair followed by your immediate tumble into the 250X abyss never to get out alive (both good & bad...) Click & you'll see what I mean.

Rick probably spent no time riding since that website must have taken years to post. As much as I want to inform people I never could have done that. He's a fricken Jeneous(Genius). Lets see him clear a triple on that website.:thumbsup:

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Heres what I did.06 R headed ported,stage 1 H/C,High compression 13.5.1 piston R pipe stock header and all the CCC mods.That probably put me close to right about 35 hp.Not a big fan of Big bores.

No matter what you do engine wise the X will never feel as punchy as the R with the wide ratio tranny and a heavier fly wheel.You can change the Fly wheel though.

If you want to keep your AIS system just port your head and run a

highcompression piston and new cam.

As stated, RHC 06-07 Head, his valves and springs. The 08 cam or the 04R cam.

the X head needs lots of epoxy to make it flow.

13.5 piston, cut head .007" gave me close to 14:1. CHM exhaust or Bill's ( both dynoed well). R flywheel. Vortex Ignition Or graft in the R box.

I have close to 38HP compared to the 32hp stock using the same dyno. Later we added a 262 kit and modded carb, gained maybe 1/2 HP but more torque that is very flat curve.

But the wide ratio trans is a 2 bladed sword and your type of riding may or may not like it, Terrain or style ??.. Also the X is heaverr, the best I can get without removing the e start still has it about 18 lbs heavier on a real scale.

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Heres what I did.06 R headed ported,stage 1 H/C,High compression 13.5.1 piston R pipe stock header and all the CCC mods.That probably put me close to right about 35 hp.Not a big fan of Big bores.

No matter what you do engine wise the X will never feel as punchy as the R with the wide ratio tranny and a heavier fly wheel.You can change the Fly wheel though.

If you want to keep your AIS system just port your head and run a highcompression piston and new cam.

semms like I've read that the AIS works by adding air into the exhaust stream, and is not really a factor in power production. SO.... The there would be zero gain in blocking it off, but removing it would be a plus in weight reduction. Right or wrong?

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As stated, RHC 06-07 Head

What M.Y. (model year) is your X? I just got an '07 250X (sold CRF450X). What is "HC" above? Is not the '08 R head best? The little 250 kickstarts so easy I'm wondering if I should have just gotten the R model.

I'll reread Rick Ramsey's section concerning X & R head changes per M.Y. Possibly the head was improved enough in '07 such that a bore kit is its best first motor upgrade.

his valves and springs

Sorry, but what is meant by "his"?

The 08 cam or the 04R cam

Does above mean only '08 & '04 MY "R" cams? Why not '05-'07? Is not the cam from one particular R model year best? Does M.Y. of the "X" make a difference? If yes, how?

CHM exhaust or Bill's

Links available to one or both? Estimated difference?

R flywheel

For trails/woods would you be more inclined to the X flywheel?

Vortex Ignition or graft in the R box

Estimated improvement vs. X? Which one of the above do you recommend over the other?

I have close to 38HP compared to the 32hp stock using the same dyno

19% hp boost is pretty darn impressive!

262 kit and modded carb...gained maybe 1/2 HP but more torque (&) very flat curve...wide ratio trans is a 2 bladed sword and your type of riding may or may not like it

For trails/woods how do you rate the R vs. X ratios?

Many thanks!

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What is "HC"? Why not the '08 X head

I think I know this one...Its not "HC" it is RHC as in Ron Hamp C ( not sure about the c really) But the guy had a head prepped by Ron Hamp. The reason for not the 08 is it uses valves with smaller stems i think.

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What is "HC"? Why not the '08 X head

I think I know this one...Its not "HC" it is RHC as in Ron Hamp C ( not sure about the c really) But the guy had a head prepped by Ron Hamp. The reason for not the 08 is it uses valves with smaller stems i think.

Thanks for your help. It may not necessarily be the "reason"...but yes, per Rick Ramsey's website, R valve stems dropped .5mm from '07 to '08. I THINK this does NOT apply to X models.

Just read the www.motorycleusa.com '08 Japanese 250F mx comparo: CRF250R picked winner unanimously by all riders novice through pro-level. Also won every category, most unanimously.

Hmmmmm.......How much might I miss the X's magic button considering how easy it is to kick start these modern little 250s? (Still can't believe guys used to kick start '50s-vintage half-liter Euro singles...talk about separating the boys from the men! Think Danica Patrick could start one if her life depended on it?)

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HC......High Compression

08 R head has smaller diameter valve stems.

Got it! Thanks!

Let me guess: Potential power gains are the only known reason for Big Red to shrink the stems, right? (Hard to deny the '08 250R's power from what I've read...)

And I bet forum members perceive a potential for decreased reliability, resulting in them favoring the '07 & earlier R heads, right?

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I just finished mine, literally two days ago.

I’ve got a buddy who went hot cam stage 2 and big bore, and he’s been disappointed with the results. My bike with the following mods will destroy his (we both have ’05 250x’s):

Dr D. SS pipe & Header

07 R Head w/ port & polish (compliments of AS Racing)

Ron Hamp’s SS valves

08 OEM R Cam

J&E high-comp piston

172 main jet / 42 pilot jet

air box cut

After I got the jetting correct thanks to the help of Agent Smith & White Stallion, this thing has more snap than my 08 TE450. It absolutely smokes!! :thumbsup:

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Potential power gains are the only known reason for Big Red to shrink the stems, right?

I aint real bright sometimes...but what do smaller valve stems have to do with ptential power gains?

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Less mass equals less spring tension to control said mass. Less spring tension equals less valvetrain resistance. Less valvetrain resistance equals higher rpms and a faster spinup.

The motor compresses the valve springs, resutling in some power loss; it would appear the lighter the valve the less spring tension is required resulting in (unknown) potential power gains. Yamaha's '08 MotoGP 800 w/ pneumatic valve actuation (no springs) is taking no prisoners three races into the season. There are apparently no springs known to man capable of operating the valves at the RPM levels, whatever they are; only Yamaha knows & they aren't telling...

As an admitted hobbyist & absolutely a non-pro my estimate is the thinner valve stem has more potential power gained via smoother flow through the ports (less turbulence as the fuel air mixture & exhaust gasses rush over a thinner valve stem in the ports).

Please correct my silliness as appropriate!:thumbsup:

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would the lighter valves result in longer valve life too?

I'm thinking the opposite: heat is the valve's worst enemy; I'd presume the thinner the stem the less it can dissipate heat. But the bottom line is Big Red obviously thinks decreasing the stem from 5.0mm to 4.5mm results in a valve w/ acceptable longevity for the intended use, regardless of any reason for the decrease.

The bike is pretty close to SOTA (state of the art) for its type (off-road riders would fall off their bikes if you appeared on a CRF250X only twenty years ago). Honda doesn't expect to see many 250s in Iron-Butt rides. OTOH they do expect it to withstand a certain amount of abuse at the hands of enthusiastic dirt feinds like the ones lurking about these pages.

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Dr D. SS pipe & Header

07 R Head w/ port & polish (compliments of AS Racing)

Ron Hamp’s SS valves

08 OEM R Cam

J&E high-comp piston

172 main jet / 42 pilot jet

air box cut

After I got the jetting correct thanks to the help of Agent Smith & White Stallion, this thing has more snap than my 08 TE450. It absolutely smokes!! :rant:

Do you mean it flat-out beats your '08 TE450? If so: WOW! Am I correct in assuming you do NOT recommend a big-bore kit? Did you loose power/torque anywhere vs. stock? The more I read about these little suckers the more I like them!:ride::thumbsup:

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