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440_Turtle
01-16-2007, 08:10 AM
so im going to convert my 400ex to a yz426. I need to know whats all is involved. I have done alot of reading and have a pretty good idea.

FRAME- NO Modification other than Radiator mounts

Oil tank - going to have a custom sheetmetal one built

Radiator - Stock 250R radiator w/ engine ice? Will that cool enough for trail riding, or should i go oversiezd? If so What size, kind?

Motor Mounts - buy a kit from ss440ex

kicker - ???? Ive heard of extensions and what not but open to suggestions here.

Throttle - YFZ cable

clutch cable - ???? Do i use the stock yz cable w/ my RTC levers??

Exhaust - Going to buy a HMF/ Yoshi 400 slip on and build custom mid pipe

Rear suspension - i dont have to change to a no link do i?? I can use stock 400 rear

Am i headed in the right direction.

Also open to suggestions about Colors,

heres what im thinking, White/Gray, Laker Customs, Black frame/swingarm/ Lower a-arms. Chrome subframe/ stem/ Upper a arms

Silver/gray Spindles

Black rims

01-16-2007, 08:47 AM
Frame has to be moded no matter what. Needs mounts and the stock mounts need to be cut off.

Yz motors run hotter than the air cooled ex motor. Mine boils over around 20 minuts during the summer and i runa 250r pwr radiator. The pwr is not much bigger than stock. Nacs looks double the size of the pwr.

ss440ex only has a couple mounts left cause he is not making them no more.

you use the yz clutch cable and it hooks up to stock clutch lever fine.

rear link is fine


to extend the kicker yo ueither buy a extention or make your own. To make your own you buy a extra yamaha nuckle and then put a 1" piece of aluminum tubing between the two.


For me to have every thing modded so i could just put the motor in and go costed me only $270. I just found a guy that welds for a living and he welded it and made the front motor mounts out of aluminum.

BuiltBlaster88
01-16-2007, 01:16 PM
Basically the only costs in doing my yz 426 swap were the cost of the engine/exhaust/electronics/ and a new radiator. If you have access to some metal scraps from a welding shop, a welder, and a little bit of ingenuity you can do it no problem. I went about the swap in a little more of a non-traditional way. I chopped the diagonal frame rail in front of the engine and put in 2 vertical frame rails to make it look somewhat like a v when viewed from the side. (I'll get pics to show you what I mean) I then made radiator mounts in between those 2 rails, and made oil tank mounts on the engine side of the back rail, and was able to utilize the stock 400ex oil tank. You will have to set everything in and mock it up exactly how it has to be, then line the sprockets up, weld a crossmember on the bottom side of the frame for the bottom engine mount, and then cut ears for that and mock them up and tack them in place. You will have to make some special bushings for the swingarm to space the engine over correctly. For the kickstarter, the guy above me is correct..go to your yamaha dealer, buy another knuckle (about 30 bucks) and then place a piece of pipe in between the two to space it out, and then smoke it into place. (Make sure it's straight!!) Then there is still the head stay and lining up the intake. There are a few different ways to do this...I'm in school right now and kind of pulling stuff off the top of my head so if you really need some help and advice send me a pm..I've converted two 400ex frames for yz engines with great success.. Also, make sure you gusset the frame in every area possible..those yz engines have a motherload of torque and like to break ****..

oldskoolex400
01-16-2007, 01:24 PM
i would deff get a aftermarket rad.

01-16-2007, 01:31 PM
Originally posted by oldskoolex400
i would deff get a aftermarket rad.

It s going to need a duzzen rads just to keep it cool.:eek2:

440_Turtle
01-16-2007, 01:36 PM
BuiltBlaster88 check your PM's

ss440ex
01-16-2007, 02:47 PM
Oil tank-yes you will need one or do the wet sump system.
I sold my last one a week ago.

Kicker- buy a $32.00 yz knuckle machine off the post and weld a 1 inch piece of tube between the two.

Throttle cable- use the yfz 450 quad cable.

Clutch cable- the one off the yz bike will work great.

Exhaust- Use the yz header pipe and which ever silencer off a 400ex, have a 6 inch mid pipe made. I like the Thunder Alley header pipe. works great and looks super high tech!!

E-mail me for any help with pics!!
Thanks again,
Al

440_Turtle
01-16-2007, 05:52 PM
is there a difference in teh mounting of a yz450 and a yz426?

ss440
You dont sell those extension do you, thats just a pic of what i need to make?

ss440ex
01-16-2007, 06:45 PM
Yes I can do a extension for you...

The lower mounting bolt hole on the 450 is located maybe .200 towards the rear of the engine then the yz426.

Kits will work either engine.

pm me on the kicker extension..
Al

440_Turtle
01-19-2007, 03:27 PM
Has anyone had any issues with tranny failure, ive heard that the trannies from dirt bikes take a real beatin when you put them in quads due to teh extra traction and weight that they are havign to haul!

ss440ex
01-19-2007, 03:43 PM
Not at all!!
2-426`s
1-444
1-450

Much better then the two Honda 450r`s I own!!:D

440_Turtle
01-20-2007, 12:02 AM
Good News!

:D

KingpinsEx
01-20-2007, 10:51 PM
Turtle where do you plan on getting your engine?

440_Turtle
01-20-2007, 11:56 PM
I got it from a guy on the site RUTHLESS, who was parting out 2 Yammie dirtbikes, engine shoudl be here next thursday/Friday

440_Turtle
01-22-2007, 04:38 PM
ANyone used a 450r Radiator in a 400ex frame? I might a have a lock on a good used one but not sure how it will work in teh frame,

2 fast for you
01-23-2007, 04:46 PM
so all you have to do is motor mounts on the swap

BuiltBlaster88
01-25-2007, 12:51 PM
I haven't been on here in awhile, sorry I never replied to your pm turtle..but all the pics of my stuff are on my buddy's camera yet. I never actually documented the actual conversion since it was done in the middle of summer, but now that I got her all down to the frame I got a bunch of pics. we've been pretty busy with all our projects so there hasn't been much time to be on the computer. If you consider yourself a competant welder I would do my method of converting it as it is the most cost effective as you can utilize the stock 400ex oil tank, and the design of the frame rails aids in strength. I used 3/16" flat for the engine mounts, seems to be plenty strong, although 1/4'' wouldn't hurt. I'll do my best to help out with any questions you may have. The total cost of converting my frame was basically just 6-8 hours of my time.

woodsracer144
02-03-2007, 09:22 PM
ss400ex, can you do me a HUGE fav.? can you take pics off the mounts for my, i found a 400ex near by and its kinda tore down and themotor is fine and iwas thinkabout buyin it and sellin the motor and buyin a 426, but i need to know how much it will cost me, i dont wanna but it sell the motor and not have enough to get a motor and get her in the frame to ride it,
thanks! how much are the mounts that you make? how much ca you get off a stock 01 400ex motor?

440_Turtle
02-08-2007, 02:01 PM
decided not to build the hybrid, going to get a 700 raptor instead SO... i have a 426 engine, harness, carb, kicker and header for sale as well as SS440ex's engine mounting kit to make this engine work in an ex frame. If you want it pm me some offers.

440_Turtle
02-08-2007, 06:15 PM
pics of carb and electrics to follow

hskers82
02-08-2007, 09:11 PM
How much for the carb