400ex engine mods (416/425/440)

[mrrilla]

I want some opinions between a 440 kit and a 416 or 425 kit. Either setup will be camed, have exhaust, rev kit, and carb. I know the 416 doesn't have the heat build up that the 440 has, but I will lose some bottom end. Will the 416 rev quicker? Opinions on either setup would be appreciated.

I also want to get some opinions on the LRD exhaust.

[duneittilludie]

i can recommend the 440 kit which is what we run in my wifes quad that is set up for the dunes.we havent experienced any overheating problems and at times we run that quad pretty hard at the comp hill.my wifes quad will run dead even with a stock raptor up a hill or on the flats in a drag race it only gets passed by the raptor after fourth gear and even then it is only behind by two or three quad lengths.good quality high octane gas 92-94 also makes a difference.check my information about our quads on the bottom of the page to see what my wifes bike is equipped with, the total package works very well together.i hope this info helps.[img]i/expressions/face-icon-small-cool.gif[/img]

[JakalWarrior]

My friends is a 440 with an XR cam and 10.25:1 piston. It dosent get hot unless its jetted wrong, only problems so far are the head bolts backing out. Royal pain in the arse to get to them to tighten them or replace the head gasket. Its not as fast as I thought it should be though, stock raptor takes it in 3rd or 4th which means it only has like 31 or 32hp (stock raptor has 34 and weighs a good bit more). Guess If you want the rest of the power you have to port the head and get better headers. It does have massive torque in this form though. I would know because im the only one with a truck so if his quad goes somewhere, I go to even if my machine isint working so then we have to share. Goes the other way too, mines bout to be running and his is still stuck with screwd up valve cover bolts.

[cals400ex]

if i was doing it i would be getting a 406 or a 416. mainly for reliability. i would assume the 440 will pull harder/rev faster assuming you have the same mods/engine builder. the 425 i have not heard of. i think you may be talking about the 426. like i already said though, i would probally go with something smaller for durability/reliability. even though you may have a little less grunt.

[jchappy]

I have had my 440ex for about 8 mo. now and i have had no problems with it. I beat z400 and raptors all the time. In a quarter mile drag race a raptor might win by a few bike lengths but hey he is still 220cc biger than me. If you are going to do it go all the way 440 or nothing you won't be dissapointed.

[drewx]

my borther has a 416 it revs quicker and has a higher top speed that the 440, but the 440 does have more bottom end than the 416, but after driving my brothers 416 i would't need any more power in the bottom because it is hard enough now to keep the wheels on the ground when going through the gears.

[DCryder]

All of these kits are going to build up heat. The 440 will handle the heat better because it comes with the oversized sleeve. The 416 & 426 uses the stock sleeve and is bored .080" and .120" over making the walls thinner and more likely to warp. As far as revving, the 440 should rev just as high as long as you have the carb, cam, and dont forget the head porting. I built and dirt dragged a 440ex w/hotcam stage 2 and E-series complete exh last year. There were a lot of 440s built to the gills and only one blew up. He broke a rocker arm and destroyed his head. Since were close to the subject could someone explain to me the point of a rev box that goes to 10,500 rpms when your horsepower peaks below 8,000 rpms??? The only time I ever hit it was sitting at the tree with the clutch pulled, or missed 2nd gear :-(

[MegaCrash]

The 440 kits have a good reputation for power and reliability, and the cost would be the same. Go for the 440.

[pleasure4qt]

Your peak power is down lower yes but with the higher rev box you can let it rev out alittle higher which is sometimes nice to have in certain situations tackling some terrain and wide open logging roads while your buddies are blipping on and off the rev box your leaving them in the dust.

[TrX465]

How high is your compression?