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440 kits
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Posted by: yub350

I know this question has been asked a million times, but when i search it i can't find much. I want to know everything that i will need to do a big bore 440 kit to my 05 400ex. I am looking for a strong, reliable kit also. And what other mods go best with this and how can i keep it cool. thanks

Posted by: cals400ex

ross, je or wiseco should be fine. i run the ross pistons because they are lightest. you can also get a light piston pin from ross to take off a bit more weight, which i also have. i would just get any of the 440's and thermal coat the piston. then you can run thinner gaskets to get a better flame travel across the top of the piston. if you want to run cooler yet, get a thermal coated exhaust pipe and a FST oil cooler. most of the engine builders i talk too say the air scoops are a 100% waste and won't do anything, thus i won't even put them on my bike. i just ordered a set for my buddy but i won't use them. that is up to you, many like how they look.

Posted by: jonc623

i just took my 440 kit off my ex and am going with the je high comp 426 i had alot of problems with head gaskets on the 440 kit

Posted by: Summit79

I recently picked up a Weisco 89mm piston, sleeve, gaskets, and stage 2 hot cam on e-bay for $280 Buy it now. If you only plan on puddle hopping, there’s no cheaper way to go and they're always available.

Posted by: yub350

Thanks for the inputs guys. I am currently looking into Wiseco and into getting an oil cooler from jegs.

Jonc623- Will a 426 kit make as much power as a 440? I want reliabilty and power.

Thanks.

Posted by: QuadJunkies

quote:
Originally posted by yub350
Thanks for the inputs guys. I am currently looking into Wiseco and into getting an oil cooler from jegs.

Jonc623- Will a 426 kit make as much power as a 440? I want reliabilty and power.

Thanks.

I have the 426 and the 440 and a 426 I was very pleased with it . I just wanted more so I decided to try the DR440 kit and have been pleased with it as well... Also, no gasket issues so far with it

Posted by: jonc623

so far from what i have seen the 426 is pretty comparable and more reliable at least with mine i had hd studs in my 440 and still had problems with gaskets

Posted by: eagertorace

a 416 build right IMO is better and way more reliable.

Posted by: QuadJunkies

quote:
Originally posted by eagertorace
a 416 build right IMO is better and way more reliable.

a 440 can be equally reliable if done properly,so can a 426...

Posted by: underdog78

i got the 440 in mine and i have not had a single problem except the timing chain which i replaced with a crf chain

Posted by: cals400ex

if your on a tighter budget, i would do a higher compression stock bore, 406 or 416. you won't need to buy a sleeve this way and you won't need to get a new sleeve pressed in the cylinder. you will just need to bore out your current sleeve. what ever you do, make sure you put in a cam at the same time or don't even mess with the piston, in my opinion.

Posted by: rYan01400EX

My buddy here in town, who races here say's his 440 blows all the time.. I told him I was interested in one and he told me to look into a 416 or a 426 due to the fact that 440's blow quite often.. Not sure if this is true, but I know it is for him, cause his does blow all the time.

Posted by: yub350

Hey guys, thanks for the replies. Money is no problem, i just want some more power out of my 400. The guy who will be doing the kit is very good with quads and knows the best mods to do. I might look into the 426 kit. Don't really want any problems while riding. Thanks again

Posted by: fmf732

440 stroker 416 (?) piston/ +4 stroke crank.. easy to build really reliable if money isnt a question..

Posted by: yub350

I was thinking about having it stroked, but really didn't know much about it. Also if i do decide to get it stroked, will i need a different pipe? Im currently running a white bros e-series.
Thanks

Posted by: fmf732

stroked can use same pipe. biggest thing is gett ing the correct cam/ port type for the extra stroke and degreee difference the stroke has. the 465 runs very good. (440/ + 4 stroke.) rev's hard and has great bottom end. with proper preparation these can be very reliable great motors. ( 50+ hp easy)

Posted by: underpowered

i love my 426kit. my buddy just put a 440 kit in his 400. in a drag race i can beat him by about 3 quadlengths, but mainly because mine revs quite a bit faster than his does. i would do a 426 befor i did the 440, JMO.