400ex 440 bigbore kit

[dmfm4744]

2005 400ex stock

will i be able to put the 440bigbore sleeve on a stock cylinder or will i have to buy a new cylinder

[Mrs.Nightbreed]

426 is the farthest you can go on the 400EX without replacing the sleeve and/or cylinder. Also, you will want to put the heavier head studs in it if you plan on putting any kind of compression to it.

[cr500pro]

i have a 2005 trx400 with a 440 kit,the kit brought the new cyl.head with all new heavier valves,springs,valve seats,cam shaft,piston rings the works..since i dont like loud bikes i have it with a stock pipe n jets..the up side of the 440kit,the bikes hauls ass n is super powerful 4 a 400cc..the down side of it.. it heat up like an oven,it will cook ur legs,my header pipe  glows like a flare,i use 20w50 oil due to the over heating ,ur starter motor n battery suffers alot more when u crank it due to the added compression,ive known guys with 440 kits that have burnt there starter a few times in a year..ur motor is gonna be alot noisier  due to the race camshaft,its gonna sound like a sewing machine @ idle..your MPG is gonna drop a good deal n it runs best of 93 fuel..good luck.