Engine upgrades

[midwest honda]

Im wanting to know what everyone considers to be the best engine package for the 400ex while retaining most of its original Honda reliability. Thats why i bought it in the first place. I also don't want to spend an arm and a leg for the upgrade. (Meaning I dont want to spend so much that a 450r would be the better way to go) I am undecided between a 416ex, a 440ex powroll big bore stroker, a big bore 440ex, and a Hot Rods/ Hot Cams 460ex big bore stroker. If possible list personal experiences of either or any of these upgrades.

Thanks for all the info.

[midwest honda]

anyone please

[adawg89]

Some people have done 416 + 7mm stroker (I think some correct if I'm wrong) to equal a 440.... a 450r carberatur I heard has better response also if you on a budget remove air box lid or get pipe with K&N air filter. That's just some suggestions.

Edit: Where in Missouri do you live? I live in KC area.

[midwest honda]

ty the 416bore plus 4mm stroke is 440


Edit: 1 hr west of St louis on I44
Funny u live in KC area. i was there on friday-sunday where at

[adawg89]

Originally posted by midwest honda
ty the 416bore plus 4mm stroke is 440


Edit: 1 hr west of St louis on I44
Funny u live in KC area. i was there on friday-sunday where at

I'm about 30 miles south of KC actually I'm mostly in belton

If you want the great reliability dont bore it out. If you have to I would just go to the next size 406/407cc. Stay with a 10:1 compression piston, maybe throw in a HRC or xr400 cam, and some bolt ons. Thats reliability. I know you can build a reliable 416 and up but it wont be as reliable as a 406/407 and Honda parts keeping it close to stock but still getting the gains

[latheboy]

This is the setup I prefer....

Bore it to your next overbore. 406, 416,426, even 440 wont make a noticable difference if its built right.
Go with 10:1 of 11:1, your choice. Heavy duty head studs are a must for reliability sake. (GT thunder)
Put in heavy kibblewhite valve spring kit, (so the valves will take the extra revs),crf cam chain, put in a stage 2 hotcam, aftermarket rev box, slipon exhaust, 450r carb with an open airbox.
You can get all that stuff for around $600, max? Around here it cost m $50 to bore a cylinder and $50 for cleaning and cutting the valves in.


Your 400ex will scream. I have built two of them this way and I can hold them wide open all day on the ice oval and they love it. For me, they both have been reliable as new.
My latest build is a '99 i bought off craigslist for $500. I built the motor and ice tires and have just over $1000 in the whole thing. (it already had an exhaust and cam chain)

[midwest honda]

wow thanks for the info guys!

does anyone have any experience with a big bore stroker kit like powrolls bore to 416 stroke to 440 kit?

[odog]

it all depends on what type of riding u do i ride with a lot of big bikes and im very competitive i say just ride it until it breaks and when it breaks go to a 460 but if ur the biggest bike in the bunch that u ride with than just do a 416 kit when it breaks

[midwest honda]

Usually it is riding with my family. Two recons and a gator so you can guess the amount of competition there. I can beat the gator in first gear lol. But sometimes i ride with a kfx with i think a 435 in it and a mild modded z400. Oh and a warrior but it doesnt really count cause i can beat it already. I want something that is competetive but not something that will blow their doors right off and give me a serious loss of reliablilty. My personal choices are 416 and 416 stroked to 440 but im unsure.

[midwest honda]

Types of terrain i ride include tight and open woods. Open fields and pastures and some occasional sand.

[midwest honda]

anyone else tried any of these options or have other good ideas for engine upgrades ranging from a 416-465

[brian76708]

Originally posted by latheboy
This is the setup I prefer....

Bore it to your next overbore. 406, 416,426, even 440 wont make a noticable difference if its built right.
Go with 10:1 of 11:1, your choice. Heavy duty head studs are a must for reliability sake. (GT thunder)
Put in heavy kibblewhite valve spring kit, (so the valves will take the extra revs),crf cam chain, put in a stage 2 hotcam, aftermarket rev box, slipon exhaust, 450r carb with an open airbox.
You can get all that stuff for around $600, max? Around here it cost m $50 to bore a cylinder and $50 for cleaning and cutting the valves in.


Your 400ex will scream. I have built two of them this way and I can hold them wide open all day on the ice oval and they love it. For me, they both have been reliable as new.
My latest build is a '99 i bought off craigslist for $500. I built the motor and ice tires and have just over $1000 in the whole thing. (it already had an exhaust and cam chain)

dont forget new timing chain tensioner. and it will be over 600 mine was and i didn't even do valve but i am checking the whole head to make sure its in spec(not done yet work in progress)

[Wheelie]

Do a search on strokers, this has been covered extensively.


My stroker has been running strong for 3 years without any problems to date. Very reliable and runs very strong.

[midwest honda]

im pretty set on boring it to 416. Does anyone have any pros or cons of also stroking it to 440?

[odog]

what sprockets are u running 15/38 and are u going through all your gears in the area u ride in

[midwest honda]

stock 05 sprockets with 22s in the rear and i can hit nearly top speed

[midwest honda]

I want a motor that is like the 400ex stock but with just more power. I want to keep the smooth power delivery but i would like it to be stronger in all ranges mostly mid and top end. As everyone knows the 400ex already had lots of bottom end. Thats why i think bore and stroke combo cause i have heard the 416 revs really good.

[midwest honda]

Please, i need some help from some motor building gods, or at least someone who knows what there doing. I need opinions and personal experiences.

[odog]

i have outran two 440 ex s that were completely stock with the exception of the bore with what u see in my sig if u want more top end to mid power i would suggest a stage 3 or 2 cam maybe a lightened flywheel and a cdi rev box that should help the top end out and maybe a 416 bore

[Wheelie]

My stroker has a slightly stronger bottom end than a stock EX with a pipe and filter. The mid-top end power on the other hand is very impressive. It pulls hard to the rev limit. It'll beat a piped/filtered and regeared 450 in a drag race.

[midwest honda]

About how much did u spend on the 440 kit and all the machining and other parts to go with it. I have a pipe and air filter already.

[Wheelie]

I did the tear down and assembly myself.

The price for the crank work w/hd rod, piston, cylinder work, porting, timing chain, cam, etc was about $1200.

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