RFS bikes Vs. CRF450X

[sugarshane]

OK,

So I own a 2008 CRF450X and I am looking at a 2007 KTM 525 XC.

I am 5'9" so the lower seat height of the KTM is pretty appealing, as is the lighter weight. I weigh about 245lbs when bulking and about 215lbs after cutting down so more cc's is always appealing to me.

My X has a JD jet kit, opened air box, smog removal kit, full FMF exhaust, R&D flex jet fuel screw for performance mods.

The X is my first big bore thumper so I don't have much to compare the 525 to. So is there anyone here that has ridden an uncorked X and a 525XC? I have searched but cannot find much info comparing these two bikes to each other. I also own CR500's so I obviously like strong aggressive bikes. From what I have read the XC seems like a great fit for me. It is deceptively fast with strong pull and wide power curve, SX based engine with 2 more gears, stiffer suspension, etc. I live in AZ so I will be using it for desert riding, dunes and Hare Scramble type of riding(I don't race). No MX and hardly any single track and the single track we do have is pretty open.

So basically I am looking for info on how these two bikes compare.

Also what are the things for me to look for on KTM's? I am only interested in RFS's engines as I have known people around here to have issues with the 08+ bikes but rarely here about issues from RFS engines.

Edited May 18, 2011 by sugarshane

[gravelfreak]

There is no limit how much power you can take out of an rfs, just a question of money. But rfs is cheap to build.

[colorado450]

I bought a used 06 450 xc. I rode my friends 07 450 crfx a few times. I like the xc for it's 6 speeds and ease to adjust the valves. I think the Honda frame is superior. The KTM will hold it's value longer and with six speeds you can run much lower gears. The KTM suspension is more plush also. Just my opinions.

[Spr Dave520]

IMO the RFS is a much better trail engine, and the KTM frame geometry can be set up just as easily. I couldnt get confortable on a 450x. 10 minute valve jobs on the KTM seal the deal.

[skypig]

10 minute valve jobs on the KTM seal the deal.

Gives me something to aim for!! Do you drain the radiator?

[FORMA MOTO]

CRF450X:

- stronger construction/durability

- longer lasting motor (substantially)

- better Showa suspension (although it needs re-valving)

- very very stable at high speeds

- tons of motor still left in there with a few mods

- heavy (actual and feel)

- tall and wide

- slow turning (pre '08) and needs critical sag adjustment

- only a 5 speed

- can be made into an absolute monster motor desert bike

KTM:

- lighter (actual and feel)

- turns more neutral

- power band is more flat and useable on sketchy terrain

- 6 speed

- fragile crank, shift drum, inner shift fork

- PDS suspension (narrower range of tuning)

- will never be a monster motor bike

[gravelfreak]

CRF450X:

- stronger construction/durability

- longer lasting motor (substantially)

- better Showa suspension (although it needs re-valving)

- very very stable at high speeds

- tons of motor still left in there with a few mods

- heavy (actual and feel)

- tall and wide

- slow turning (pre '08) and needs critical sag adjustment

- only a 5 speed

- can be made into an absolute monster motor desert bike

KTM:

- lighter (actual and feel)

- turns more neutral

- power band is more flat and useable on sketchy terrain

- 6 speed

- fragile crank, shift drum, inner shift fork

- PDS suspension (narrower range of tuning)

- will never be a monster motor bike

Did you get almost everything backwards or is it just me?

No need to drain or remove radiators unless you're actually adjusting the exhaust valves. I'm lazy so I let them go tighter than specs before adjusting, usually never need to drain the radiator for the valve job alone, just let them wait until removing the radiators for a bigger maintenance project or something.

[smithpa68]

Agreed!! Mostly backwards.

The only one I agree with (besides the six speed comment) is PDS has a narrower range of tuning. They are sensitive to springs and sag for sure.

Never be a monster motor? Couldn't be more wrong. Check this out if you doubt.

http://www.djhcyclesport.com/Custom_Engine_Work.

My RFS has 433 hours on it now. One piston/ring and two intake valves at 305 hours. Try that with a Honda. And that is all racing time. Even a trip to Baja.

[FORMA MOTO]

Did you get almost everything backwards or is it just me?

No need to drain or remove radiators unless you're actually adjusting the exhaust valves. I'm lazy so I let them go tighter than specs before adjusting, usually never need to drain the radiator for the valve job alone, just let them wait until removing the radiators for a bigger maintenance project or something.

Hmmm, backwards? The X is almost 30 lbs heavier, and the center of gravity is 100mm higher....

The X is 46hp uncorked, the 525 is 43.

The X with an R head and cam is 59hp.

[Chas_M]

CRF450X:

- longer lasting motor (substantially)

- can be made into an absolute monster motor desert bike

KTM:

- fragile crank, shift drum, inner shift fork

- will never be a monster motor bike

Absolutely backwards.

The RFS engine has one of the best records in the history of dirt bike engines for reliability and longevity. Plus, the basic RFS engine is one of the best for building reliable monster engines. I just sold my still very strong '04 540 EXC with 14,000+ miles and 640 hrs on it to a good friend of mine. The bottom end of the engine is all original and untouched. Needless to say, my friend is a happy camper.

[jar944]

The X with an R head and cam is 59hp.

considering the R isn't making 59 or close to 59 I'm not buying that.

as for absolute HP and TQ the KTM can be made to have more (with more displacement)

[smithpa68]

I think I found this dyno chart on TT a long time ago that showed the 2003 KTM 450EXC at about 46 or 47 hp. I can't vouch for the source though.

[weantright]

Hmmm, backwards? The X is almost 30 lbs heavier, and the center of gravity is 100mm higher....

The X is 46hp uncorked, the 525 is 43.

The X with an R head and cam is 59hp.

More like X uncorked is 46HP but with $$ for an exhaust and jetting.

X w/R head, cam, jetting and exhaust would be 49HP

525 is 43 stock with no extra $$

I am lighter with all my gear and found the 250X handled, rode and an all around better bike. Have not rode a 525 but did ride a 625, outside of power the 625 felt the same as a 450X.

[michigan400]

I think I found this dyno chart on TT a long time ago that showed the 2003 KTM 450EXC at about 46 or 47 hp. I can't vouch for the source though.

Thats from Dirt Rider mag. I have the issue (2003 or 4) at home still from when I bought my XR400. If memory serves correct here, one test I read from Moto USA, I think the '06 off road test, compared HP #'s and said the 450X, WR 450 and KTM 450EXC all were around 42-43 hp. They said the Yammi had the most at 43, the X was 42.something and so was the EXC. Who knows how accurate that is but I think it shows all the 450's (except for my beloved XR400) are pretty darn close power wise, atleast on a dyno.

[Rodzilla]

Absolutely backwards.

The RFS engine has one of the best records in the history of dirt bike engines for reliability and longevity. Plus, the basic RFS engine is one of the best for building reliable monster engines. I just sold my still very strong '04 540 EXC with 14,000+ miles and 640 hrs on it to a good friend of mine. The bottom end of the engine is all original and untouched. Needless to say, my friend is a happy camper.

Gotta go with this. Especially w/the RFS. TONS of '00-'01-'02 bikes STILL going strong. We are now a decade out for these bikes and they are now showing the need for some top end TLC.

Never be a monster motor? Really. Guess those guys running the big CC RFS motors are slackers!:busted:

[jar944]

Never be a monster motor? Really. Guess those guys running the big CC RFS motors are slackers!:busted:

The big (over 640cc + ) RFS motors are in the 80's

[jfgjr]

I lilke the low seat height of the KTM, but you can lower the CRF with a subframe lowering kit that does not affect the suspenders http://speedmetaldesigns.com/SubFrameLoweringKitMainPage/tabid/37/Default.aspx

I have had an RFS bike for a few years it has been bulletproof. It does vibrate a bit more than some modern designs, the forks are harsh (but I am 150lbs) oil changes kinda suck, but overall I could not be happier.

[Chas_M]

The big (over 640cc + ) RFS motors are in the 80's

Really!?

The RFS engine, beginning with the KTM 520, was first made in 2000. Since then, literally 1000's of 'monster' RFS engines have been built from 532 - 600++ cc.

[jar944]

Really!?

Not common but possible, though 64-65hp is possible out of the RF4 450's

Team Peterson claims 82 from their 637 and 85 from their 662 on VP C16

more common is 70-75hp from the 637-662cc motors

[akarob]

Really!?

The RFS engine, beginning with the KTM 520, was first made in 2000. Since then, literally 1000's of 'monster' RFS engines have been built from 532 - 600++ cc.

I think he meant 80HP, not 1980's.