Bottom End Hit

[XJ400ex]

Hello everyone, so here's the deal. I bought an 01 400ex a while back and I've been modding it to get it set up exactly how I want it. I ride mostly tight trails in northwestern Pennsylvania and only ride a track maybe 3 times a year with it so I'm going for low to midrange power. I honestly couldn't care less if I lost a ton of top end if it hit like a beast on the bottom and pulled solid through the middle. So far my mods are:

JE 11.1 high comp piston
Stage 2 Hot Cam
Ported and polished head
450 cam chain
39mm FCR
Full PC exhaust
Uni with outerwears
450r shocks
YFZ450 front brakes
450r rear brakes
And a bunch of other crap that has nothing to do with this thread

Anyway, I love the set up so far except that my bottom end sucks. Midrange is fantastic and the top end power pulls super hard. Like I said, I really want to make big power down low and I'm willing to sacrifice top end. Where do you guys think I should go from here? It has to stay reliable but, I'm willing to spend the $$ to get there. Thanks!

[400man]

i have the exact same motor setup except i have a stock head and lightened flywheel, and air box lid on. id say maybe if you went with a stock ported head it might give u some low end back? other than that, maybe go to a stage 1 cam? whats your gearing at? i run 14/38 and i stay in 2nd and 3rd gear in the xc races, with enough torqure to where i hardly ever use the clutch enless i gotta stop.

[XJ400ex]

My gearing is the same as yours 14/38. I was thinking about changing cams and going to a 416 but, I don't know what cam would be good for what I'm looking for. Honestly, I was really happy with my ex till I rode my buddy's 525 outlaw and I was blown away. I've never ridden anything that hit as hard as that KTM motor. I know the ex will never be like that but, I'm looking for that style of power.

[400man]

by hit, do u mean like how a 2 stroke powerband hits, where its almost like a light switch? or was it just like smooth powerband with gobs of raw torque and power? i think a lightened flywheel would help you out, it will let the motor rev up and down quicker, similar to a 450. it goes along good with the fcr carb if you have it jetted good.

[CJM]

Strange, that should make great power all around.

Jetting?

My 400 was similar but I put the 04-05 450r carb on it and no porting and went with a 416 originally-no power issues. Sucker was like a tractor, nice power all over. You cannot compare it to the outlaw at all-it will never ever come close unless its bored, stroked and so forth and by then you mighty as well buy a 450.

[LxMxL97]

by hit, do u mean like how a 2 stroke powerband hits, where its almost like a light switch? or was it just like smooth powerband with gobs of raw torque and power? i think a lightened flywheel would help you out, it will let the motor rev up and down quicker, similar to a 450. it goes along good with the fcr carb if you have it jetted good.

I thought that lightening the flywheel was bad for the woods bc the motor won't lug down as low without stalling out?

[XJ400ex]

by hit, do u mean like how a 2 stroke powerband hits, where its almost like a light switch? or was it just like smooth powerband with gobs of raw torque and power? i think a lightened flywheel would help you out, it will let the motor rev up and down quicker, similar to a 450. it goes along good with the fcr carb if you have it jetted good.

I'm looking for gobs of raw torque for sure. My jetting is perfect as of right now but, I do have the stock flywheel. The motor revs pretty quick as it is, it just seems a little sluggish on the bottom end. I feel like I'm clutching it up more than I should have to

[XJ400ex]

Strange, that should make great power all around.

Jetting?

My 400 was similar but I put the 04-05 450r carb on it and no porting and went with a 416 originally-no power issues. Sucker was like a tractor, nice power all over. You cannot compare it to the outlaw at all-it will never ever come close unless its bored, stroked and so forth and by then you mighty as well buy a 450.

The FCR was by far the best mod I've done. Other than getting it jetted, which took FOREVER, it has been amazing! Perhaps I'm just asking too much for what I have. The 525 is a monster but, it's also a totally different motor.

[400man]

yea, they say it will make it stall easier if you lug it in a high gear at lower rpms. I guess it depends on how you ride it. ive had mine done for awhile and I guess ive just been used to it and never have any problems.

[Blodg]

The obvious answer is to go to 13 tooth front sprocket or even 13-39 to get the most low end. What size tires are you running? With similar motor mods on 20" tires I never need to slip the clutch on my 416EX when blitzing trails and I never use 1st gear. If you have 22" tires you could even go to a 12T front sprocket.

[XJ400ex]

The obvious answer is to go to 13 tooth front sprocket or even 13-39 to get the most low end. What size tires are you running? With similar motor mods on 20" tires I never need to slip the clutch on my 416EX when blitzing trails and I never use 1st gear. If you have 22" tires you could even go to a 12T front sprocket.

I'm running 21" fronts and 20" rears. I just came off of a YFZ450 so I'm pretty used to slipping the clutch a lot. Maybe I'm just not trusting the motor enough to not stall. This weekend I'm gonna try letting it lug and resist the urge to pull in the clutch lol if it doesn't work I will try dropping a size on the front sprocket.

[CJM]

you can pretty much let the quad idle along if you turn the idle up enough, I used to do it all the time.

[MtnEX]

Right... there is a BIG difference in the two types of power... and you ride them differently and they also have their ups and downs and uses...

I have went back and forth a ton to know....

Anyways, the 400EX has good smooth woods power. Great for riding anywhere all day, or a long grueling XC race such as a GNCC. It does not have that lightening punch of a 450 and needs shifting a LOT to get that kind of feel out of it... like shifting down into second and flogging it on a corner exit... when it has the lugging locomotive type power to exit just fine in 3rd or 4th... just ain't straight arming you.

You are best off just to ride it as a smooth locomotive in my opinion and not expect it to overly excite you like a 45-50hp 450 race motor. The benefit is it is a lot less tiring and you can take it pretty much anywhere, make a lot of mistakes and it just keeps going like an old tractor instead of stalling out.

The 450 on the other hand has that hit and excitement and will just rip when you get on the throttle, provided you clutch well and have good gear selection. You'll run 2-3-4 on them mostly, and struggle even in 1st through technical areas that are no sweat on a 400. Where on a 400 you'll run a lot in 3-4 and sometimes in 2nd if you need some punch or have some challenge.

They are just different animals, and I kinda prefer the 400 type power for long rides or XC races, and the 450 style power if I want to cut up, rip, blow off steam, etc...

I have found that honestly I really like an LTR450 set up XC... seems to have a nice mix of both.

[CJM]

Honestly comparatively speaking I found once you mod an 04-05 450 it rides close toa 400ex in that you can lug it some, even stock its easier to lug. Carb has a smooth power deliver vs the 06+ and the FCR carb. 06+ does NOT like to be lugged around, you must be on the the throttle or really know how to ride the machine in order to lug it.

[450rtt]

450's don't lug anything like a 400ex. I've had about 3 different setups on a 450 motor and I can tell you the 400ex's are lugging machines, you snap a wheelie from damm near a stop. All my 450's require some clutch to get it up out of a slow roll. I run a 42.5mm fcr carb and that thing has 10x's the pop that a stock 04/05 carb has. This is coming from a guy who's actually run FCR's bored not bored as well as the stock carbs. Input is great but people tend to give advice based on what they have read. I've run all the carbs and i can tell you the pop you get from an FCR hits much harder than the doggy stock 04 05 carbs.

If you really want some more snap in the woods run a stage 1 hotcam, those things will tear your arms off. The only downfall is that they do fall off on the higher revs. I ran one for a year and loved it int he woods.

[400man]

Right... there is a BIG difference in the two types of power... and you ride them differently and they also have their ups and downs and uses...

I have went back and forth a ton to know....

Anyways, the 400EX has good smooth woods power. Great for riding anywhere all day, or a long grueling XC race such as a GNCC. It does not have that lightening punch of a 450 and needs shifting a LOT to get that kind of feel out of it... like shifting down into second and flogging it on a corner exit... when it has the lugging locomotive type power to exit just fine in 3rd or 4th... just ain't straight arming you.

You are best off just to ride it as a smooth locomotive in my opinion and not expect it to overly excite you like a 45-50hp 450 race motor. The benefit is it is a lot less tiring and you can take it pretty much anywhere, make a lot of mistakes and it just keeps going like an old tractor instead of stalling out.

The 450 on the other hand has that hit and excitement and will just rip when you get on the throttle, provided you clutch well and have good gear selection. You'll run 2-3-4 on them mostly, and struggle even in 1st through technical areas that are no sweat on a 400. Where on a 400 you'll run a lot in 3-4 and sometimes in 2nd if you need some punch or have some challenge.

They are just different animals, and I kinda prefer the 400 type power for long rides or XC races, and the 450 style power if I want to cut up, rip, blow off steam, etc...

I have found that honestly I really like an LTR450 set up XC... seems to have a nice mix of both.

I have to agree with all this (except about the LTR, cause ive never rode one haha). I rode a buddys 06 450r he got and it feels a lot different than a 04-05 450. the snappy power feels awesome in the open when playing around in the field and stuff, but in the woods I had to really concentrate when I got to some tight slower speed trails. my 400ex has some decent work done to it, and a 39mm fcr, but it still didn't compare to his 06 450r. mine feels downright slow in the open where his feels like your on a dirtbike. it had a hmf slipon and it had a way louder and deeper sound than even my old "shorty" exhaust.

in the end, it made me appreciate my 400 a lot more. sure it may not be the fastest, but its a lot easier and more comfortable to me and that 450, and I can still hold my own at xc races.

[MtnEX]

Yeah, it is two different animals, and good for two different things, unless you ride like every day or two and work out like mad and stuff. Really really really serious XC Race program basically. Otherwise, that hit won't do crap but make you tired or lead to mistakes in the woods. Just my opinion... and riding style I guess.

Suspension, stabilizer and protection are far more important, and some gas and service money to ride a lot more.

All in all, sick as I feel, I think personally I will be parting ways with my 400EX and my KFX450R... for two LTR450's, 2 sets of Flexx Bars, 2 sprocket sets for XC, and 1 set of minor mods to share between them for the moment. One I am lining up already has everything I want so I may end up slightly better set than that. But power wise, they are going to be basically stock. Stock as in about all of them have a cherry bomb and baffle out or pipe.

At the end of the day, I have just seen what I can do on an LTR a few times over, and I am another class of rider on it. Fits my riding style and fitness level far better. It's comfortable, stable, smooth power and ride... just more what I am looking for to race on.

The only worry I have is I am not 100% sure I can live with the width once I drop it back with tire/wheel selection. I may have to do a Honda/GT Thunder style ball joint mod or even buy a set of arms, but big whoop. Decent arms are half the price of arms for a KFX450R. So it is no biggie as long as the smooth ride remains.

[slightlybent47]

Looks pretty good except for the Uni.
I still prefer the stock foam filter with an outer foam filter over that.
Yeah I know! I've heard it before!
I still prefer a motor that will survive dusty trails and muddy holes over the minuscule HP gains you get with a after market filter.
Not meant to be a lecture or a debate, just an opinion.:D