I have now had my 440 kit installed for over a week. So this is short term review but should give some insight since all these people claim they have the kit but dont write much about it.

Bike and Mods:
2001 400ex
Uni Air filter
DynoJet Jet kit (155 main)
IMS 440 kit using a 11:1 CR piston
XR400 cam
Running 93/110 octane mix 1/2-1/2

I broke the bike in for about 5 hours for really opening her up. Seat in the pants power noticed much different powerband. This most likely all due to the new cam. The bike really pulls from mid range on up to the high revs. This is where I remember the bike sorta falling flat. Bottom end definately suffered. There still is decent bottom end there, but not the power it once had (mainly because of using the XR cam which was designed for the weight and traction of a dirtbike). This is really noticeable when climbing large hills that bog the bike down to low revs. Where stock the bike would keep pulling the bike really wants to die. Since I am a avid hill climber I am thinking of switching back to the stock cam, but the power hit in the midrange is quite nice so I am not sure if I will switch back. The bike is also harder to wheelie. Not that it is hard to get the front end to come up, this is easier, but to balance the bike and ride an extented wheelie is harder because of the lack of power down low. This may seem weird but I its harder for me to ride long wheelies compared to the bike in stock form.

Tech tip: torque all bolts down properly and make sure the oil rings are installed properly, because a common problem is to not install the wire holder that comes with the center oil ring.

 

Hmm, who else has ahd this problem with the XR400 cam? I like to do hill climbs too and dont want that area to suffer!

 

I do alot of hill climbing, and with my setup (416 kit, xr-cam), I do just fine, but did have to change my riding habit's a bit...Try to keep it in the middle of the power range when climbing a hill...you can't just stick it in one gear and crawl up the hill, you have to put some ***** behind it.

 

So is the XR cam more like ridding a 2-stroke powerwise? I mean, its still gotta have some down low as it is still a 4-stroke, but you gotta keep the revs going a little more than just let it torque out of anything?
I am considering trading my R for a 400ex, but I kind of like the 2-strokes and am used to riding that, I dont want to be lazy and just let it torque its way out of anything, so with the XR cam it sounds like I maybe can still ride it like a 2-stroke a little bit?

 

It is alot pipier than a stock 400ex is, but isn't quite that feeling you get from a two stroke.

 

Sounds like a nice setup. Mild Porting and maybe a 3-5 angle vavle job and you'll get a bit of low end back. Maybe a pipe and silencer to. I just got my 440 also and i like it (both times i'v ridden it [img]i/expressions/face-icon-small-tongue.gif[/img] ). I blew the head gasket because i was running that 11:1 piston and running 93 octane (no turbo blue around here) i thought if i DIDNT lug it i would be fine but it eventully blew my head gasket. I also ordered a 10:3:1 piston from White Bros, but they sent me the wrong piston so i coudlnt race this weekend, what a mess. I cant wait till i get to ride the 440 again.

ryan

District 23
District 23
#82

440 mods:
White Brothers 440 big bore, 12:1 piston, White Brothers Cam, White
Brothers Rockers, valve springs with titaniam retainers, 3 angel valve
job, porting, Ct full race exaust, White Brothers Rev Box, K&N air
filter, Removed Airbox Lid, Lonestar Chrome +4 axle, Lonestar +2 Aarms,
Lonestar Chromoly Tie rods, PEP front shocks, Rear Turf Tamers (18’s)
mounted On BEADLOCK rims, Rikens up front, Douglas rims, Timmy Boy
Stainless steel Braided Break lines, Renthal Bars, oury grips, SvA
Clutch Perch, Lonestar Parking Brake blockoff, Nacs handebar Clamp,
Nac’s beadlock mud caps, Nacs throttle clamp, Trimmed Front Plastic,
Custom Headlight(s) Cover, Ac Mudscreen Bumper, AC Pro Peg Nerfs, Pro
design Kill switch, 16tooth front sprocket, Graydon Seat

 

Yes it is MORE like riding a 2 stroke, esepically with the 440 kit. There still in great bottom end, but just not as much as stock. When I am talking bottom end I mean really low bottom end. Like maybe from 1500rpms down. The bike leaves the line quick, has a nice midrange punch, and pulls as far as you dare to rev it. But under extreme loads (huge hill) the extreme bottom end is less powerful than stock. This is the case with most high performance cams though. You are gaining mid and top end power because of more lift and duration but you are loosing bottom end.

I will probably stick with the XR cam, put if I just had a stock 400 motor Im not sure I would. It really depends what type of riding you do and what type of powerband you like. 2 strokes climb hills great, yet they have little bottom end power compared to 4 strokes. So the bike will still climb easy, just need to manage the throttle different. The difference is similar to changing gearing. Just have to determine if the change is good for your style of riding.

I would have to admit that the bike would most likely be quicker on the track with this powerband for most riders, esepically those use to 2 strokes.

 

300exster,,if you weren't putting a hard load on the motor or revving past half throttle the head gasket shouldn't of blown. 93 octane should be sufficient to run the motor lightly with no problems. It should actually take a hot day, and high revs + high loads to blow the headgasket that quick running 93 and 11:1 cr. Sounds like you might have another problem. Are you sure that is the only thing that happened? You might have other internal problems that caused the head gasket to blow (i.e. low oil)

 

Actully riceburning, i was at FULL REV ALL Day and it was about 85degrees all day also, it was pining to beat hell (when at full throttle) so i dropped to very low revs until i got back to the truck (40 miles or so), and found i had a blown head gasket, it was the octane

ryan

440....