PDA

View Full Version : How to do the yz/ex conversion.



Mxbubs
09-19-2002, 03:15 PM
READ THIS THREAD IN FULL BECAUSE I AM ALWAYS EDITINGIN IT AND ADDING TO IT AS I TWEAK OUT MY BIKE. CHECK FOR UPDATES AND CHANGES WITHIN IT.

How to do the yz/ex conversion.
Before you begin anything, you need to become good friends with Mcmaster-Carr.com. They will have most everything you need. You will need a good welder, and a good machinist can save you alot of money from having to be ripped one by EastcoastAtv.

Here is a nutshell of the obstacles.

You will need 2" flexible air duct hose to make the carb boot work with the Ex stock setup. (Jcwhitney.com)

The motor needs to move to the left exactly .600 thousands, or six tenths of an inch.

You will need to build a custom oil rezzy, or you can use your stock ex rezzy buy mounting it to the back side of the replaced vertical bars behind your radiator (you'll see).
You will need to weld mounting tabs for the bottom center motor mounts, and for the top (head stay).

The ex pivot bolt is too small of OD to fit snuggly in the pivot bolt hole of the motor, so you will need to knock the two bushings out that are already in the hole, and replace them with a custom machined bushing/sleeve that is 3.5" long. I forget the exact OD and ID of the bushing, but 3.5" long will fit everything snug.

Added 4-07-03. Or you can buy a 5/8" bolt at the hard ware store, and use it. It will fit snug in the yz426 case/bolt hole. HOWEVER, you will need to drill the frame out, and drill out the swingarm needlebearing bushings/spacers. The only way to drill them out is with a chromed MASONRY bit. The spacers/races are so hard, they will eat up a regular bit. If you gusset the pivot area, I would go with the 5/8" bolt.

You will need a grinder, buy a good one. A dremmel would also be a good idea.

The Kickstarter needs to come out exactly 2.5". The cheapest and a good way to do this is simply buy another splined knuckle from yamaha, they are 30$, have a sleeve made exaclty 2" long and weld the sleeve between the new one and the one you already had. The take a grinder and cut the kicker mount off the one closest to the motor, you wont need it. If you have a good welder, this WILL work and WILL not break. I have a friend that gave me this idea.

My oil rezzy is3.5"X 3.5" by 9" long....You can go longer, but I dont think you can go much wider, I couldnt go any taller because of my big radiator. That size rezzy gives me about 1.75" quarts of oil in the rezzy, and then I add some more once the motor gets its share. (Kinda like the 400ex) The stock yamaha bike calls for 2 quarts, fyi. You can buy 12" by 12" sheets fo aluminum from mcmaster-carr.com, as well as the nipples to weld to it for your fittings.

On the water input side of the motor, the fitting on your water line going into the motor is a Y fitting, and this will not work. You will need to get the output side hard pipe that from Yamaha for about $30 and cut it off real short. It is a 90 degree piece, slide your hose up on it and clamp it down. It will miss your pipe fine.

Baldwin makes the throttle cables for 30$.
Trinity makes the custom pipes for 430$.
I think trinity sales the mounts identical to the ones I have. I got mine from Adam, the front bottom mount tabs (ears) is what I am refering to.

Mxbubs
09-19-2002, 03:16 PM
You can see the 3/8" nipple welded to the top for the oil line coming out of the top of the motor. Your input side for your motor oil is on the right side of the motor, you have two outputs, one out of the top and one on the bottom left of the motor, like the 400ex.

Be very careful when welding your drain plug. (bottom right), if you weld it sticking out too far, it will not slide in easy between your vertical frame supports, and if it sticks too far down, you cant get a wrench and bolt in the nipple because it will be too close to the bottom frame.

Mxbubs
09-19-2002, 03:36 PM
If your oil can is mounted too far forward, your stem will lobe will rub it....Look at the arrow on the left.....I goofed up and didnt realize this, so I had to make some tabs to move my oil rezzy back, I didnt want to cut and grind the tabs I had welded to the frame because I had already powdercoated before I goofed up, so I just made up for it by adding tabs to the front of the oil rezzy as seen by the arrow on the right.

Mxbubs
09-19-2002, 03:39 PM
Again, this is the front of the rezzy. I got some aluminum spacers, by the way, alot of hardware stores carry aluminum and steel spacers, did some grinding on them, my oil rezzy fits very snug, its not going anywhere. I used the aluminum sleeves from the top of the motor mounts on the ex motor to weld to my aluminum rezzy. You will not need them for the top motor mount on this motor.

Mxbubs
09-19-2002, 03:43 PM
Here is your oil rezzy fill. I used 3/8" couplings for the 3 oil line fittings, and I used barbed brass nipples coming out of the 3/8" couplings and just slid my hoses over them, they have yet to leak.

You can see the spacers, they are .600. Moving your motor over to the left lines up your sprockets.

I used 1/2 aluminum couplings for the drain and fill.

Mxbubs
09-19-2002, 03:55 PM
There is only one spacer on the bottom right side, and it is .660 thousands, you dont put any spacers and the bottom of the mount tab to the frame.

Oh yeah, make sure you elevate your rezzy so it will go over your nerf bars, and make sure it isnt too high to where it wont fit because of your radiator.

Mxbubs
09-19-2002, 03:59 PM
Here is the spacers I used on the bottom center to help hold the motor from moving left to right. Notice how they are cut in half on one end so they dont hit my frame tube, instead they butt right up againts the motor tabs I welded to the bottom of the frame on each side. If you really want a snug fit, slide a washer or two between the spacer and motor.

Mxbubs
09-19-2002, 04:00 PM
The left side bottom spacer.

Mxbubs
09-19-2002, 04:03 PM
This is the oil line output of the motor and back into the rezzy. (bottom left side of motor) It took some serious bending but I got it to work. It does not leak. NOTE: USE TWO PIPE CLAMPS!

Mxbubs
09-19-2002, 04:09 PM
Right side oil line, motor input.

Mxbubs
09-19-2002, 04:15 PM
Here is the 2" ID air duct hose. I had to grind the gusset to make it fit good. I took a piece of 2" OD pipe and slid it into the end of the air duct hose and taped it up for a good seal, and slid it into the existing air duct boot, but I had to trim my air boot back an inch or so.

Mxbubs
09-19-2002, 04:16 PM
I gusseted the pivot area too.

Mxbubs
09-19-2002, 04:17 PM
I will have pics soon of my kickstarter.

Anyway of getting this stickied?

The finished product.

Mxbubs
09-19-2002, 04:21 PM
I cut my angled frame supports and got 3/4" od carbon steel pipe and made vertical supports to house my Jansen Racing Big radiator......you dont have to do this with a stock R radiator.

tants
09-19-2002, 04:37 PM
thats awesome!

NTPracing22
09-19-2002, 07:03 PM
is this all on a stock frame?

NTPracing22
09-19-2002, 07:09 PM
or could it be done on a stock frame?

400exBro
09-19-2002, 07:48 PM
Yup that is a stock ex frame with the mods done to it so the engine would fit.


bubs- were are the pics of you riding it, how do you like the power out put, and was it worth the money and time to do it????

man that looks sharp, with the blue fullboren plastic it looks really good.
lata
Bro

CHAUNCY
09-19-2002, 09:03 PM
How much was the total to make the conversion ???

spincr4hire
09-20-2002, 05:39 AM
sweet quad dude !

NTPracing22
09-20-2002, 06:01 AM
Congrads man! you did a great job. it looks very clean, and very fast. hah. so how long did this take? it looks like you'll have a blast on it. keep us posted for any problems you encounter, if any!

Mxbubs
09-20-2002, 02:11 PM
Yeah, its a stock frame. I sat down and did the figuring, I figured if you bought everything from scratch this bike would be around 14000$ I had the frame, spindles, and gas tank left over from parting out my old bike. I am waiting on my ceramic coated pipe from Adam Sick, and a full set of carbon fiber rims and holeshot tires from Jeff. I dont know what problems I am going to encounter, Im sure Ill have oil leaks, I FEAR mostly frame cracks, but my father is a machinist/millwright, and I know these quads weak points, I think we made a real solid bike. Im not so much on looks, I am very big on a solid bike. Everything is solid. Nothing to vibrate off or come loose. It has taken me 8 months, I wanted to do it myself, take my time, and do it RIGHT. Ill have action pics soon I hope.

Mxbubs
09-22-2002, 04:52 PM
and more.

Mxbubs
09-22-2002, 04:52 PM
more.

banshee-rider13
09-22-2002, 05:08 PM
i like the a-arms what kind are they

Mxbubs
09-27-2002, 11:07 PM
They are the Hermmanns +3 long travels with 19" quadruple springed Elkas.

09-28-2002, 07:19 AM
really nice quad!!!!

Mxbubs
09-30-2002, 03:41 PM
I finally got my pipe in and cranked it! I couldnt run it because I dont have my water system hooked up yet though!

Here is the pipe, I love it, the quality is awesome. It is designed by Adam Sick and sold by Trinity Racing, it is Ceramic Coated.

I also got my kick starter done. Like I said, I bought another splined piece from Yamaha for 30$, my dad made me a spacer 2" wide and welded it between both of them, and then I cut the kicker mount knob off the one closest to the motor because I am not going to use it. I had to get an 8mmx1.25 that is 90mm long, or about 3.75" long I think, bolt to hold it on the shaft.

Mxbubs
09-30-2002, 03:42 PM
On bike.

Mxbubs
09-30-2002, 03:43 PM
My pipe. Ceramic coated.

Mxbubs
10-05-2002, 09:55 PM
I finally rode it today, it RIPS!!!!!!! I am very impressed and it IS VERY EASY to crank if you know what you are doing. Im glad I got this motor over the crf450.

Team Outlaw #34
10-05-2002, 09:59 PM
wow looks like it took a while to post that.....good job

400exRacerX
10-05-2002, 10:13 PM
You can run a stock 400ex oil tank with that setup,,, I've seen it before.

Mxbubs
10-06-2002, 07:22 PM
Yeah, I know, but it would work with my Jansen oversized radiator, Im glad I got this bigger radiator, this motor does run hot by nature, so the extra water helps. It RIPS!

Rip_Tear
10-06-2002, 07:38 PM
LOL, I couldnt help but noticing all the zip ties and pipe clamps, thats all I used to use to make everything!

lildude
10-06-2002, 07:55 PM
kool bike

are u gonna put any graphix on it??

Foxrage
10-07-2002, 04:54 AM
How much would you carge for The front motor mounts, tabs for bottom and top motor, All bolts for these mounts, kick start extension.

Foxrage
10-08-2002, 10:19 AM
do you think there is enough room to use a radiator and stock oil tank? Im going to try it. Thanks

Mxbubs
10-08-2002, 10:58 AM
A stock 250r radiator? probably so, a stock yz radiator, I dont think so. Both me and Adam Sick looked into it, and didnt see a pratical way of doing it.

The elevation of your radiator doesnt matter, so you can twist and turn it however, as long as the suction side is down, and the return side is up.

Mxbubs
12-03-2002, 03:52 PM
Took my gussets higher, that top little piece is what breaks off first.

Mxbubs
12-03-2002, 03:56 PM
head stay and carb

Mxbubs
12-03-2002, 03:58 PM
Shock mount gusset

Glow Plug
12-03-2002, 04:17 PM
OH just what i need something else that i want but can't afford lol






btw great bike

Rip_Tear
12-03-2002, 04:43 PM
Looks good, you could use some duct tape though.. :D

phatswinn
12-03-2002, 05:06 PM
hahaha duct tape thats a great one looks mint, alittle redneck but its great wanna trade?

forum
12-05-2002, 01:12 PM
good stuff!

Bean
12-05-2002, 04:03 PM
thats got more zip-ties than mine!!!!!!!!1


j/k, sweeeeeeeeeeetttttttt bike man, be she flys

joeroadking
12-05-2002, 04:47 PM
man that bike is sweet, more work involved than I thought to do the conversion, good job! now you should start building them for other people, and make some money!

Mxbubs
12-10-2002, 11:21 PM
Bearly have time to ride it. Waiting on my Carbon Fiber rims, and 250r brake setup and seat cover, she will be complete. Only thing stock is the gas tank, spindles, brake cylinders, linkage, and seat foam.:D

I zip tied extra to keep any wires from wiggling. It is really tough, Im not worried about anything when hitting big jumps.

Mxbubs
12-11-2002, 12:29 AM
How much is it worth?


CHASSIS:

Stock gusseted and powdercoated frame
LSR subframe
Herrmann Long Travle A-arms
Herrman Anti Vibe Stem
Tag Metal Fat bars
Cascade +1 chrome swingarm
X-33 axle
Nacs Front hubs
Durablue rear hubs
LSR Carrier
Stainless tie rods with FK rod ends

MOTOR:

2000 Yz 426 Bone stock, Low hours
39MM FCR carb
Jansen Racing New oversized radiator
1.75quart Oil rezzy
K&N filter and outwear
Trinity Racing Ceramic coated pipe and silencer

BODY:

Fullbore Plastic
Gripper Seat
Carbon Fiber tank cover

MISC:

Carbon Fibers front and rear
Holeshots MX's
Denton Racing Rebuildable dampener
250r front and rear calipers
250r caliper brackets
Ac racing bumper, skid, pro pegs, and grab bar
Works connection lever with Decompression release
Pro design kill switch
Carbon Fiber case guard
Renthal chain and sprockets
Stainless lines front and rear
Parking brake block off
Hinson Brake pedal
Solid Pivot bolt
LSR Locknut and antifade hub

SUSPENSION:

Elka quad rate Fronts, dual adjustable 19"
Elka dual rate rear, dual adjustable

All chassis bearings are new, swingarm, hubs, etc........

How much can I get for this?

Everything is new except the used seat foam.:D

crazy canadian
12-11-2002, 12:31 AM
i would have to say it's PRICELESS to him!! good job. looks like a real solid bike.

forum
12-11-2002, 09:00 AM
How would a 250r rad work?? should it be ok?? I live in canda remmebr so its a little cooler then southern states, but still can get around 90*F I really dont want to buy a new rad, but if i need to i will. Anyways yea i no forsure when i finish my 426 It will be chained to the floor in more then one spot!. My engine is exactly the same as bubs same year and all. But im going to get the head ported and flowed for extra BOOST!. Im trying to get my local engine builder to sponser me.

Mxbubs
12-11-2002, 10:33 AM
I HIGHLY reccommend the bigger radiator. If you think about it, heat is the #1 killer of a motor, all the other problems are just symptons of the root cause, HEAT. If you are getting any kind of motor work, DO GET THE RADIATOR! I promise you, you will not regret it. If feels good to be able to rip and ride, come to a stop and let the bike idle sitting still and not have to worry about the water reaching boiling point. Griffinrad.com can custom build it for around 300$ which is the best way to go. I got the Jansen Racing one, Im very happy with it. There is also a guy on Ebay selling some aluminun radiators that will work.

forum
12-11-2002, 11:49 AM
didn't adam sick use a 250r rad?? how is his working out?

Mxbubs
12-11-2002, 11:51 AM
Yes he did........He is a member now......I forget what his username is, find him and ask him.......I just seen that aluminum radiator on ebay for a buy it now 325$. I would get it.:D

forum
12-11-2002, 12:37 PM
so is john houser. Hes the newest member! (when i looked) OOOOOOO the batle is going to come, mark my words! hahaha. j/k

gun32boarder
12-18-2002, 05:03 PM
check out dentonracing.com for oversized 250r radiators

Mxbubs
03-07-2003, 01:41 AM
headstay

Mxbubs
03-07-2003, 12:55 PM
BK Mod

Mxbubs
03-07-2003, 12:57 PM
head stay

DGR Designs
03-07-2003, 01:54 PM
john houser is a member? jeez, lol looks like a houser/arens battle may erupt! and all us are gonna be here to watch!

phatswinn
04-08-2003, 02:42 PM
this better be in the tech area

quadracer99
04-11-2003, 08:19 AM
thank you for posting this HOW TO DO... cuz i am goin to be makin a yz426ex for a skool project and i need as much help as possible

Honda4trax250x
04-11-2003, 08:35 AM
that thing looks really really nice good job:eek2: :eek2: :eek2:

quadracer99
04-11-2003, 04:39 PM
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2410556374&category=35595

would that radiator work good??

Mxbubs
04-12-2003, 12:45 PM
Should work fine. Just have to use some big washers welded to your frame so the bottom and pins will set in, and figure out a way to hold it steady at the top. Also figure out a way to put a grill on it to protect it from rocks and sticks.

forum
04-12-2003, 04:19 PM
I finally rode mine today. THe engine RIPS!. this thing hauls!. My front elka's are too stif. but the rear is awsome. Maybe i havent broke the front in yet. but it seems realy stiff. Im calling elka on monday. I should have new mainsprings within the week

04-12-2003, 04:29 PM
hey mx bubs , you didnt tell us youc an switch with a cr 250 motor too:eek2: lol

Brad
04-27-2003, 03:33 AM
awesome bike sry about the injury tho

tdd6405
06-14-2003, 12:45 PM
whats the "BK" mod?

KASCHAK
05-11-2004, 08:43 PM
Originally posted by tdd6405
whats the "BK" mod?

SRH
05-11-2004, 08:50 PM
Originally posted by freeride132
hey mx bubs , you didnt tell us youc an switch with a cr 250 motor too:eek2: lol

shut your mouth

LTandRaptorider
05-11-2004, 09:48 PM
Originally posted by SRH
shut your mouth

Now this is too weird...:eek2:

I'm putting the bottle away and going to bed...:o

Mxbubs
05-12-2004, 10:33 AM
Hahahah....

For the record, the BK mod, is an FCR carb mod made up by Tim Ferry's Yamaha mechanic, Brian Kinney.

The carb is drilled, and tapped, and a screw is put in to push up against the cam that allows fuel to be sprayed in the motor. It keeps the motor from bogging and stalling on take off.

Roostrocket
09-05-2004, 02:01 PM
Wow that is sweet. I just bought a 426 modded frame and motor with everything ready to go so reading how hard it was to build this yourself and how long it took puts that huge grin on my face. I am curious to know what kind of radiator fluid it takes, and if you add any additional chemicals to make it stay cool. Mine will have the stock R radiator and I was going to bump the displacement to 450 or 460 so the heat thing Will probably be a factor. I was told that this bike does puke if you let it idle to long so maybee wetter water or super cool or some additive like that would help it! Also I see it is setup for the dunes, but do you have any idea's of the rear sprocket to use for mx? Anyone need an 400ex motor? LOL:D
Ps, How are the clutches on these motors? I am waiting for mine to be shipped but I was wondering if I should adapt the magura clutch or if it is not needed. What an awsome thread!!!

400exKy1e
12-06-2004, 04:23 PM
does a 426ex compare at all to ur yz426? or what could u compare it to? also, how much would u say it would cost if u went from a built 400ex chasis and all u wanted to do was get the motor n stuff

thanks
kyle

SRH
12-06-2004, 04:45 PM
Originally posted by 400exKy1e
does a 426ex compare at all to ur yz426? or what could u compare it to? also, how much would u say it would cost if u went from a built 400ex chasis and all u wanted to do was get the motor n stuff

thanks
kyle

i know you dont wanna hear it but youd be better off with a yfz, i had a built ex and the suspension and handling and cornering still wasnt as good as my yfz felt, and there isnt much of difference at all in power between a yz and yfz


but if your set on building one figure a grand to put the motor in, with hoses, spigots, radiator, engine mounts etc, the motor is comparable to a yfz,crf, etc, there is no comparison to a 426 ex motor...yz/yfz motors are way more powerful and better for mx in everyway, remeber with all the extra torque the motor produces you should gusset your frame some, i think jb use to sell kits to put a yz or crf motor in a ex chassis, youdl have to look around

stocktires
12-30-2004, 06:37 PM
Got a link to the JB racing site?
MXbubs, What gearing did you end up with for mx?

tdd6405
12-30-2004, 07:01 PM
Originally posted by stocktires
Got a link to the JB racing site?
MXbubs, What gearing did you end up with for mx?

http://jbatvracing.com/