CRF450r motor 450r motor or CRF 450x motor???

[yellow400ex05]

I was just thinking of putting a 450 engine in my 400 whenever i decide i need more power. I'm not sure of which engine is the best to use. out of the CRF450r, CRF450x and TRX 450r motor.

I know the quad motor is very detuned and has setting for a quad. And the older 04 450r engines crank bearings went out. And the newer 450r engines wont last as long and dont make as much reliable HP as the older ones.

Also what the difference between the CRF450r and CRF 450x? is it different motor wise? I know i might get bashed for this thought lol. But how are the YFZ 450 engines? Do the motors have as many poroblems as the 450r's and is there anything that would be to look out for? Or a YZ 426 engine? Please help me out here I know i have mayny many questions and I know there were probably posts about every single engine that i mentioned , if there are please post them..

Also tell me what you think is the most reliable best performing motor that wont be costly in the long run and the most difficult work to put into the 400ex's frame. Example name the motors that require ALOT of chopping and hacking of the frame for them to fit in as i don't want to cut up the frame and reweld and stuff. i heard the the yz426 engine will fit almost perfectly? is this true?? And how is the power and reliability of the motors? I also heard the CRF 450 motor is too tall and will require frame modifications..

EDIT: its okay for the frame to need to have minor cutting but not like a new kind of frame modification. Basicaly the least amount of cutting or the most. LIST them in difficulty or amount of cutting from best to worst if you can. Thanks in advance!

[yellow400ex05]

Also this motor that i may put in will be mostly stock to mods like the ones in my sig like a pipe airfilter and maybe a cam.

[yellow400ex05]

Bump....

[WhiteZrider]

Originally posted by yellow400ex05
I was just thinking of putting a 450 engine in my 400 whenever i decide i need more power. I'm not sure of which engine is the best to use. out of the CRF450r, CRF450x and TRX 450r motor.

I know the quad motor is very detuned and has setting for a quad. And the older 04 450r engines crank bearings went out. And the newer 450r engines wont last as long and dont make as much reliable HP as the older ones.

Also what the difference between the CRF450r and CRF 450x? is it different motor wise? I know i might get bashed for this thought lol. But how are the YFZ 450 engines? Do the motors have as many poroblems as the 450r's and is there anything that would be to look out for? Or a YZ 426 engine? Please help me out here I know i have mayny many questions and I know there were probably posts about every single engine that i mentioned , if there are please post them..

Also tell me what you think is the most reliable best performing motor that wont be costly in the long run and the most difficult work to put into the 400ex's frame. Example name the motors that require ALOT of chopping and hacking of the frame for them to fit in as i don't want to cut up the frame and reweld and stuff. i heard the the yz426 engine will fit almost perfectly? is this true?? And how is the power and reliability of the motors? I also heard the CRF 450 motor is too tall and will require frame modifications..

EDIT: its okay for the frame to need to have minor cutting but not like a new kind of frame modification. Basicaly the least amount of cutting or the most. LIST them in difficulty or amount of cutting from best to worst if you can. Thanks in advance!

James, whos gonna buy this motor for you?? your dad

[quadboy38]

the crf and x motors will mount up the same. i know the x motor comes with stainless valves and might be geared different for offroad but not totally sure.

[sandmanblue]

Originally posted by yellow400ex05
.....And the newer 450r engines wont last as long and dont make as much reliable HP as the older ones.

.....

Ummm, that's not exactly accurate there guy. The 06/07 TRX motors are very similar to the CRFX motors, which are also very similar to the CRF. The TRX has beefed trans gears and has some upraded parts such as the exhaust rocker arm in order to extend its longevity. In a quad, the CRF motors actually are more likely to fail due to the increased stresses involved from more weight as well as much higher traction. That beats up the trans and clutch...

You are making an assumption that the CRF and CRFX motors are better for some odd reason. I can only guess that it came from not going through the actual part numbers that make yup these engines and maybe from reading too many posts here that say the same thing.


You'd be far better off to either keep your 400 and deal with it as far as power goes, or sell it and buy a newer 450R. You'd be saving a lot of money selling yours and buying a newer 450r.

[440_Turtle]

Im just startign my 426 swap, ill keep everyone posted as to how it goes!

[oldskoolex400]

i dont understand why you would want to make a hybrid out of a pretty much stock quad, you would be better off money and time wise getting a 450 if thats what your wanting

[ninis470]

if you really want to do this then use the x engine, you be able to run lights and the gear ratios abetter suited for a wuad application... havin said that, if youre iffy about the project, save your money and go with 450r... you'll spend half as much and have just as nice a quad except with out the headaches of fine tunning... and get the 450r with the hrc kit... it's worth it...