416 0r 440?

[Waynes400ex]

I have a completely done up mx 400ex except that the motor is all stock. It is time to tear it apart and rebuilt. I would like more power. I have a cannondale also and I would like my ex to be if not as fast close to as fast as the cannondale. Reliablilty is big for me and I dont mind running race gas. What setup do you guys recommend? Carb , Valves, Comp Ratio, Crank trued and welded, oil tank everything. Thanks for your info on my questions!!!

[Steven]

Welcome.

You can build both bikes reliably. For some reason, its an on going debate here but (all things being equal) the 440 be more powerful than the 416 but not by a large amount.

To keep heat down keep c/r around 11:1. Some run much more. The stock rod works well with this 11:1 c/r. Run a cooler plug (9) heat range and race gas to keep head temp down.

There are lots of good cams to choose from. Some are drop-ins, where new OEM rockers will work well with. Others are quite radical, where aftermarket springs, hardened rockers, and shortened valve guides are needed. The more radical cams are really only good for just a few more h/p than the drop ins however.

Some run big valve heads with the 440 and some don't. The big valve heads don't seem to be any faster though. Anyway the OEM valve is a good one but some have had trouble with the intake ones going bad after time and severe stress. Kibblewhite makes replacements

I don't know much about the cranks so I won't speak about them.

A good 440 will give a cannondale fits!

Steve

[Waynes400ex]

Thanks for your input. how do you feel about reliability between the 440 and 416? Also what about carburators?

[eldoexrider01]

with common science in mind. a bigger piston means more explosion space on the piston surface which means more downward force on the crank and rod. so if built equally the 416 should be more reliable. but it also depends on the compression ratio cuz an 11:1 weisco 440 is not the same compression as a 416 11:1 kit. (as read in other posts) if done right the 440 can be reliable enough not to be aproblem, although if for some reason u think u might have a good chance of blowin ur top end in a race or somthing, u will possibly hafta get it re-sleeved. (440) instead of takin the 416 up to a 426, as a last option before the 440 anyways. as for heat problem u might wanna invest in an oversized oil tank. since u will be running mx and not very fast speed (like tracks around my place) the extra money to get one with holes in it may not be worth it (example pingrys (holes)against a K&K oil tank(no holes). its all up to preference. as of carburators, most people say that the bigger the carb the more top end power u get. i dont have expereience with carbs as in tryin different ones, but this is what i have read on the site. if not an up jetted stock carb a FCR 39MM would be about right.

[Varmit57]

I ran a 416 for a while and had absolutly no problems or complants with it. It raps very fast and is a good power boost over stock. When I went to a 440 I lost the quick rev but I gained a TON of bottom end and more power yet, that made the bike a lot more fun to ride...
The clutch wore a bit faster and it did run a bit hotter but you have to expect that!!!!!

[Waynes400ex]

So for a carb the fcr is worth the money? I have heard it is hard to get jetted right and that the throttle pull vs. a stock is alot shorter? What oil coolers and oil tanks does every one prefer to keep there 400ex cool? Where can i find them ? also a 440 i would need to get port and flow and three angle valve job? I only have to mess with the valves if i go with a big cam right ?

[Steven]

You don't need port work with the 440. I ran mine without for a long time and it was still very fast.

You also do not need valve work with a new cam but new rockers a good idea for longevity.

Any worn out engine will benefit from new valves and a three angle valve job.

400ex carbs are quite good flowing carbs. You can remove the choke (see f.a.q for details). There is some power to be had with an aftermarket carb on a 440 though.

[raptor_02]

it depends on how much money you want to spend. To make a 440 reliable it will cost atleast 1000 dollars to where a 416 would only cost about 500. A 440 national kit would put you in the mid 40's for horsepower. I don't know what a 416 kit would put you at but i'm guessing around 35hp with just the piston and cam. But to get the 440 in the mid 40's you would have to spend over 2000 bucks. That's alot of money. So I have decided to go with the 416 if I can ever get started with it. But you have a big wallet, go with the 440.

[NTPRacing#19]

i like the idea of a 416 for mx alot. a quick revving motor is good for mx. also alot of bottom end grunt is good for mx. i guess its all in your riding style

[TEAMPHIL]

I would recommend the 440. We install 4-5 440's a month and have had no problems with reliability. we dyno test every kit and the average seems to be about 41 h.p. We install the 11:1 je piston, port the head, we install either a web hot cam stage 2 or a stock xr400r cam both with the stock rockers, use a metal head gasket (eliminates the blown head gasket problem) thats a .025 thickness, a CHM system P4R exhaust and a dyno jet kit. This kit has tons of low end grunt and plenty of mid and top end. Its a blast to ride. I personnaly use vp red race gas mixed with 92 pump gas. works great and my race gas lasts a little longer. Rev box not needed with the 440 kit.

[Steve-o 400EX]

Basically its all about how much money you want to spend. A 416 is an awesome motor that revs quick and has a lot of power, but it is also very affordable. If you want to shell out some cash and do a 440, that is also a great motor if done right. If you do it cheap then you will probably get blown away by 416's. If a 440 is done right then you will have a fast quad on ur hands. Do some pricing research and find out how much each will cost, if you want to spend the cash i would recommend the 440 but if not go 416. either way you will be happy.:D

A good 416 kit with a cam and you do the work will be around 400 bucks.

A 440 done right will be over $1000.

Also i would only get a carb with a 440, if you get a 416 then just take the choke out of the stock carb and that should be sufficient.

Good luck!

[dj416]

i just rebuilt mine with a 416 11:1 weisco piston, stage 1 hot cam, head ported an polished, racing valve job (5 angle) added rro circut pipe and k&n and removed air lid box. its still in its break in period but next weekend i'm taking it to the honda shop where they got a dyno and u get 3 runs for 40 bucks. i will post the results soon as i get them. but as of right now its fast as hell.

[Dune Surfer]

I had a 416 but wanted more grunt. the 416 revs great but I wanted nore. I have a 426 now and like it better, still revs fast but has noticably(sp) more grunt. You might consider throwing 426 into the mix.
I did the work myself and it is pretty easy. with the $$$ you save get porting done.
as far as carbs go most people here like the fcr 39, some have the quicksilver, others the lectron. I chose the lectron because it is just as strong on top and half the price.
I used the hotcams 2 because you don't need springs and rockers, pretty good top end cam.
Replace your cylinder studs whatever you do, sparks has them so does rocky ridge racing.
You can order all of your parts from C&D the are very fair.
I went with the ross piston at 11.2-1 compresion, the ross is lighter.
Plan on running race gas or at least 50/50 mix.
good luck:)