what would it cost me to modify my 2005 400ex into the 440 mod ... and is it worth it to make it 440

 

250 -300 piston and sleeve, 100 cylinder work, 250 labor. and yes to any one who likes to go fast, its worth it.

 

i honestly would do a 416. the 440's we built had more torque but were actually a hair slower when dragging, most noticable on top end. i would get a 416 piston for around $125, gasket kit ($40), camshaft to fit your riding style ($120-150 for a hotcam), etc. boring around here costs about $100. many places are cheaper than that for just boring though. with the 440, you need to get the stock sleeve removed, cylinder bored, and then the aftermarket sleeve installed and bored/honed to match the piston you got.

 

we built a 416 for my wife and its fast .

 

Dont waste ur money on boaring out to a 440, just freakin do what i did to my quad to urs and ull smoke anyone in the mountains.

 

I just couldn't resisit jumpin in on this question. I was contemplating as well weather to buy the 440 or not, thinking is it worth the money or not??? After making a few trips to the dunes I was getting the urge to want more power. I looked into what kit to buy (416, 426, or 440) i said hell with it i will just buy the 440 and spend the extra couple of bucks. I love e-bay, i have bought most of my aftermarket parts for my 400ex off e-bay and so far no problems! I searched around for the right deal and finally purchessed an 440 11:1 kit that includes 440 piston, new sleeve, all new top end gaskets, and a stage 2 hotcam, all for $280 shipped. I live in a small comuntiy so i couldnt have anyone local do my engine work so i browsed the Web for a list of companies and decided to go with LA Sleeve, I called and talked to a very nice sales rep and she told me what to do, what to send and how much, for the re-sleeving of the cylinder and honing of the new sleeve it only costed $115. so after all said and done I will have $420 into the engine including shipping of the cylinder! so you could have a 440 in your bike for probably clse to the same amount. There are a come extras you should also look into after, your either gonna need all new jets ($10) or a 440 carb ($350), and what i just bought is some air shrouds ($60) that direct more air twords the motor for cooling, (some say its a necisary others disagree) I got them cause they look cool and they for sure can't make anything worse. So if you do it right and smart you will be somewhere around $500, Mine is still in the shop I will let you know how it runs when everything is DONE!

Good Luck Bill

 

i agree about doing it right...... the problem you have is that you don't know much about the kit you have. i am betting you have a wiseco piston. am i right?? this 11:1 440 wiseco piston was rated at a TRUE 9.5:1 compression ratio with stock thickness gaskets. i never had a problem with the LA sleeves. you will need to make sure there is proper clearance between the sleeve and the case. if there isn't the proper clearance, the piston will bind when going up and down. you will have less power and it will blow much sooner. i would make sure you have a FULL pipe. we tried the slip ons and they didn't even work worth a crap on mild 406 motors. well, they worked fine. we just had HUGE power gains after we switched to FULL hmf's, x-4's, x-6's, etc.

 

what about a white bros pro mag full exhaust u think that would be a lot bigger gain??

 

If you really want a 440ex,, You should also have,,, at the minimum, a clean up port.. cam,, carb, exhaust,,
I also have, an oil cooler,, adds a little over another 1/2 quart of oil to the system and drops cooler oil onto the cam...helps run cooler..

 

go 416 and an fcr 39mm carb. 440 your odds of having problems rise dramatically and you don't get much more.