440 big bore down to 416 bore

[98cummins]

Well for starters I would like to introduce myself since I am new to this forum. My name is Tom, I am not new to forums or how they work. But, my question is I bought a 2001 400ex with a 440 kit in it and I use the bike for trail riding mostly. I want to down size since this engine runs so hott. I am currently in the process of pulling the motor for a rebuild since I blew my head gasket last riding trip. So do you guess think it would be worth trying to down size or mount a cooling system or what. Any help or suggestions wanted.

[78ta]

to go from 440 to 416 you need a special sleeve. I have heard that LA Sleeve makes one, but I don't know if it is special order or what. Might wanna email them


I would like to know what they say, update this thread or pm me if you find out about the sleeve.

[hypersnyper6947]

If the sleeve you have is still good i would just stick with it, run some 20-w50 amsoil synthetic in it to help with heat, maybe mount a fan on the oil cooler. Im pretty sure they have to bore your cylinder w/o the sleeve in it to be bigger to actually accept the bigger 440 sleeve. So to go back you will need a new cylinder or if LA sleeve does make one to go back, but i have never heard of that, im not saying its not possible. It will be winter in no time and you wont have to worry about the heat so much, especially if you mount the fan and run synthetic. Make sure your jetted correctly also, running lean can make it run hot.

[86 Quad R]

if my memory serves me right. the big bore sleeve/kit that is made by LA Sleeve are 87mm out of the box(= 416.128 cc's) and need to be bored out to a 89mm to get the advertised 440(actually a 435.480). you could go this route and simply have a machinist to swap them out or ya could have a virgin OEM fitted for the kit.

[98cummins]

How do you go about mounting a fan? Where do you point on the oil cooler or engine? Pictures would be greatly appreciated.

[86 Quad R]

do a search. there are plenty of info on the subject. aswell as info on air shrouds?

[hypersnyper6947]

for info and pics of the fan look at the thread 440ex cooling.

[98cummins]

alright thanks guys

[98cummins]

Ok i plan on ordering a fan to mount on my oil cooler, but is there an aftermarket cooler i could order that may be bigger? I looked and couldnt find anything. Also i plan on getting a new piston and piston rings but what the stock compression on these engines and whats the differnce between the 11:1 and 12:5 i beleive is what i saw. I plan on getting a cam and making sure my carb is jetted right. I have searched and didnt come up with want i wanted to know

[Pipeless416]

check four stroke tech for a larger oil cooler.. or the cbr1100 cooler