CRF450/400ex conversion..."How it's done"... w/ pics

[416exmx]

Ok, a few guys have ask how it is done in a 400ex frame and i will try to explain it and show pictures. hopefuly if this explains it good enough it will end up in the FAQ's. PLEASE DONT REPLY TO THE POST UNTIL I AM DONE EXPLAINING, THAT WAY IT DONT GET CLUTTERED RIGHT OFF THE BAT.

**these first two steps with the swingarm and axle machining are optional... if you want the chain to be aligned you will need to do this though.. other wise i dont think the chain will be aligned properly.

#1 Here is the first thing that needs to be done to make it right. On the left inside of the swingarm (where pivot bolt goes through) you need to have the swing arm machined off untill it is flush. basicaly machine it off until the part sticking out is gone. This will allow the motor to set as far to the left as possible. this is needed for chain alignment. Then a spacer will need to be added to the right inside to make up for the macined off left side. you can see the shiny spaced on the right

[416exmx]

#2 Next the axle will need to be machined so it sets farther to the right in the carrier. The part where the seal rides is the part to be machined off. Approx 1/8”-1/4” …. Like I said this shifts the axle to the right to help align the chain. ** Like I said, these steps are optional, but afterwards, the sprockets will be in line**…

[416exmx]

as you can see, the clearance is very close on the left side of the swingarm... because axle is shifted to the right

[416exmx]

the left side frame rail will need to be cut and moved to the left as far as possible... as you can see in the picture, the left side used to look like the right. the frame rail will need to start bending left right in front of the carb, then weld it back as far left as possible. this allows room for the carb.

[416exmx]

this pictures shows:

the front tube of the subframe will need to be cut out and capped off on both ends and braced. the frame will then need to be cut out almost all the way through. then get a flat peice of steel and bend it in the curve of the cut and weld it in. A guesset will need to be added underneath this for support... you can see the guesset... this mod allows the air boot to meet up with the carb.

[JDiablo]

good info so far,very interesting to see how its done

[416exmx]

you need a top motor mount welded to the frame. you need to use the motor mount off of the bike and then just make a plate welded to the frame to mount the motor mounts from the bike.

[416exmx]

use the front mount tabs already welded to the frame and just make an aluminum front motor mount for the front. the right side will use a spacer for the bolt going through the motor

[416exmx]

you will need a new bottom motor mount. may be able to cut the old one off and just re-weld it on. a spacer will be used on each side to fill gaps between mounts and the motor

[sparky450AR]

HEY MAN!!! voting isnt till this weekend...lol jk,,,,,,great post!

[416exmx]

most radiators have pins on the bottom. make a tab on the frame from a flat piece of steel. i think i drilled a 5/8 hole in the steel, put a rubber grommet in it and the radiator pins fit in perfect... i then put a small triangle brace under it. i put the radiator right in front of the motor.

[416exmx]

the top of the radiator will have pins also. go to rural king and get a little piece that splices all-thread together. it has threads all the way through and is about 3/4" long. weld it to the frame. as you are setting on the quad, weld the right one on the inside of frame and the left one on the outside of the frame... then make a small L shaped bracket that goes over the pins and bolts to the tabs.

[416exmx]

another of top radiator

[JDiablo]

should definetly go in the FAQ section when he is done with it

[416exmx]

use two more of the same all-thread splice deals welded to the frame to hold the coil.. while setting on the quad, i put it on the left side. be sure it is close enough to the motor that the spark plug wire will reach the motor

[416exmx]

you will need two tabs on the front of the frame to hold the cdi box. notice i took the cdi off to show the tabs, but it slides on the two mounts sticking out there

[crap-banshee32]

man this looks like alot of work...:eek:

[416exmx]

for a kick start extention i bought another knuckle, cut the top tab off of it and welded a piece of tubeing between the two of them. be sure to use heavy tubing and then a longer bolt to reach the shaft

[416exmx]

you will need a water pump relocater. this is a different cover basicaly. the stock one, the spicket points almost atraight up. this makes it hard to get the hose back to the radiator, with a dream water pump cover, they point straight foward making it easy to hit the radiator spicket.

***Update- The water pump cover off a 06 450r will work also***

[JDiablo]

Originally posted by crap-banshee32
man this looks like alot of work...:eek:


your right man it does seem like a hefty load of wrk:eek2:

[416exmx]

mine uses a CRF FMF headpipe and a 400ex yoshi exhaust, you will have to cut around on the silencer tube and re weld to get the exhaust to fit... i dunno though, i got off easy and bought the exhaust already made this way... i am guessing a yoshi was used because you can move the band that mounts the silencer to the frame anywhere on the silencer helping to use the CRF headpipe.

***Update- A YFZ450 slip-on works good with the stock CRF headpipe. A little modification is still required.***

[416exmx]

use a YFZ450 throttle cable

I used a CRF450 Magura clutch. this was good because it incorporated the hot-start lever/cable in with it...

I am going to use a piece of radiator hose for a small adapter between the carb and the 400ex stock airboot/airbox. the stock set-up lacks about 2" of reaching the CRF carb...

***Update- I have also been using radiator hose for making a new boot between the head and carb. I cut the head side of the boot on two different angles to get the carb to point up and to the right a little more. It will require less frame modification than I show this way***


** The best thing to do is put the motor in the frame starting with putting the swingarm bolt through, just look at the frame and you will start to see what neede to be done... like i said i dont know it you will have to do the swingarm mods


*** READ HERE*** dont go out and start cutting on your frame just like this and then blame me if there is a mess-up. this is just a guidance showing what will need to be done. i am sure there are different ways to do this also. like i said just set the motor in there and go from there...

I AM DONE WITH THE THREAD.. thank me or tell me what you see wrong.. when you get done it will look like this







sorry wait till they post the builders thread and then you will see....

[crap-banshee32]

????? i alreayd saw? the finished product...then it went away..hehe


i think im gunna contact arens and find out about the 400ex/crf frame...and make some of this a whole lot easier...if not.. looks like im gunna be doing the same thing u did.

thanks alot man...im sure u helped many ppl


NIck

[416exmx]

haha, just a quick peak... and i topped 1000 posts while doing that thread...

arens frames are a 400ex frame that he will modify while building for the crf motor. or when i called him a few months ago, that is what he was doing. i would like to see how some of the other frames allow the airboot to line up with the carb...

[roostin_dale]

300exrida did you even see that he posted "DO NOT POST UNTIL I AM DONE"


anyways..this is a very good thread and i would say well worth the time to make...good job! And the bike looks awesome!

[416exmx]

my motor builder (a local guy) had a 4 stroke TM motorcycle, they put out more hp than any other bike... i really wanted to buy it and use it in a quad frame but he sold it before i was ready to build. he has another one a 400 that is even electric start. it would be sweet... there are only like 4 or 5 of the 4 strokes in the U.S.... i'll prolly never find another...

[howboutchaw]

Great info!!
Thanks 416exmx

[howboutchaw]

One question,

I can't deside between useing the yzf motor or the crf is there anything that that makes one of them the clear choice.

[Atreyu]

Originally posted by howboutchaw
Great info!!
Thanks 416exmx

[dukeboy]

or JB racing does this conversion for 4 or 5 hundred dollars and they have a quick turn around, they ran a converted 400ex framed crf450 in the twelve hour race and took 2nd or third in the pro class!

[dukeboy]

i had a yzf motor and my buddies all have the crf, iwould go with the crf for the simple fact of starting it.

[fastexgirl4c]

great info.. i had to do most of this with my 300ex when i put the engine in a 250R frame...its alot of work but its worth it:)

[NTPracing22]

awesome! thanks for the info man..

any finished product pics?

[Ex_Rider43]

check out the exriders.com builder of the year vote thread ;)

[gibson400ex]

GREAT INFO:D

This should go in the FAQ section for sure!:D

[416exmx]

Originally posted by howboutchaw
One question,

I can't deside between useing the yzf motor or the crf is there anything that that makes one of them the clear choice.

auto-decompression...that is the key.. my YZF426 was hard to start... this CRF450 can be started with your hand... i dont know about a YZF450 though... what would be cool is a WR450 motor and put the YZF cam and mess with the timming and you would have a strong motor and electric start...

[YamaWarr0121]

/\ and different gearing and you'd have a yfz with the cam mod done

[ckasper18]

That is a;most the same thing i did to mine the fun thing was i did mine before this was posted but when you build your own with your own design it then makes that quad yours when people ask you who did that you can say me i did that.I have done several custom fabrications and i liked every one i built and the work you pu put in to it is yours you cant blame anyone but yourself.When people come and look at it and you talk to them tell them what you did and what you would do different the next time you look like a rocket scientist who builds who builds kick butt quads.Just trying to figure out now how i can do something new is great.My next project is going to be a 996 superhawk v twin quad and plan on building the frame from the ground up still doing some thinking on that though.The way i figure it is i can sit in the house and listen to my kid or watch orang county choppers or i can do something i love doing because when your done with it you get to ride it thats the most fun of all.....Chris

[SnellCRP]

What is a TM motorcycle? Would it be possible to change the intake on the CRF motor so that the carb would come out straight instead of at an angle? Awesome post!!! Got one for a 520KTM in an EX chassis?

[Quadude32]

Very good info:D

[Ryan]

Great info! Alot more work than I thought it would be.

[Quadude32]

Thats for sure it made my mind up in a real hurry:eek2:

[brian-250]

i wanna know how to put one in a 250r frame:D

[wishin4ahonda15]

With all that work you have to do id rather just buy a 450r and call it a CRF450:rolleyes:

[Quadude32]

Originally posted by brian-250
i wanna know how to put one in a 250r frame:D



LOL now wouldn't that be a headache and a couple cases of beer:eek2:

[Alberta_Qaudin]

how about a pic of the finished product??

[Ryan]

Originally posted by Alberta_Qaudin
how about a pic of the finished product??

His quad is sweet! V

[brian-250]

Originally posted by Quadude32
LOL now wouldn't that be a headache and a couple cases of beer:eek2:


its only metal i can out think it:blah:

[416exmx]

frame is FOR SALE:
check it out...

http://www.exriders.com/vbb/showthread.php?s=&postid=1131265#post1131265

now some one should do a yz426 thred like this