all around best engine mods???

[bjjmoore]

ok guys, here is my question.

what mods are the best all around engine mods that you can possibly do to a stock 400ex engine?

now I mean what is the best performance set up? you know, is it a 416 stroked to a 440 with a stage two cam? or maybe a bored 440 and a 450r carb with a +3 timing key?

I would like the best all around mod set up for hp/acceleration/reliability

WHAT MAKES THE BEST ENGINE????

[tri5ron]

To better answer your question,
You first need to prioritize your requirements.
such as, Which is the MOST important, and in what order.

Horsepower/ Acceleration over Reliability ?,
or,
Reliability over HP/Acceleration ?

Second it would help if you were to specify what you intend to do with your Quad.

Race ?, MX, GNCC, F/T, etc.
Trail/Woods ?
Dunes?
Drags?

Also, What kind of cash are you PREPARED to spend ?

The 400EX is one of the most "modifiable" machines out there,
and has some of the most choices in aftermarket parts available.
As well as ALOT of guys, who have done some pretty custom mods, and machining, and exotic alterations, and are happy to share the "How to's" on doing it.

but the bottom line is,...
what do you want to get OUT of it,...
and what money you have to put INTO it.

[bjjmoore]

I was looking for a generalized answer on what were the best mods. I realize the response would be very opinionated.

this would be with no regaurd to money and motor mods only.

I guess you could say for the average guy wanting to make his 400 really rip without sacraficing too much reliability.
not neccesarily a racer just out rippin with buddies, you know braggin rights on an ex.

[tri5ron]

Originally posted by bjjmoore
I was looking for a generalized answer on what were the best ,... motor mods only.

I guess you could say for the average guy wanting to make his 400 really rip without sacraficing too much reliability.

not neccesarily a racer just out rippin with buddies, you know braggin rights on an ex.

Ok, about as generalized as it gets, and yes, this is just my opinion....

Reliability is naturally at it's highest, with a stock piston, and with stock compression.

Making/Modding it to "really rip" is very subjective, and has many interpretations.
So to loosely answer your question, with my interpretation of what you are asking,....
and with the priority being placed on The Average Guy and Reliability,...

(engine mods only)

A stock piston/compression set-up, with a good full exhaust / air filter/ and properly jetted, Sparks +6 key, 450r carb (again, properly jetted), stage 1 or 2 Hotcam (or equivelant other brand), and maybe a Monster coil, will provide some fairly impressive gains. (dyno verified)

With all of the above being the same,...

and changing the bore to a 416 or 428,
and staying below 11:1 compression,
will certainly enhance and improve, the above mentioned gains, without compromising too much reliability.

Going above that, (in compression), you'd need to remove the Sparks key, and,...
either go back to a stock key, or use one of the +3 keys that are currently available.

As well as,...
It is highly recommended that,... AT or ABOVE 11:1 compression, you should be running the HD head studs like the GTT studs, or equivelant.
(best when INSTALLED by GT Thunder, using the Roll Form Tap).

At this point, (and even WITH the HD studs installed), it is fair to suggest,
that Reliability is now less than, but not horribly bad, than the stock piston set-up.
(providing the operator has a proper and diligent maintaince schedual).

Now,... with all THAT said,....

you can start punching out the bore higher, and higher,...
or raising the comperssion more and more,...
or dropping more and more cam on it,...
or going to full Stroker,...

but , you are NOW talking about some considerable heat issues that will need to be compensated for with greater oil cooling capacities.
This is accomplished using larger coolers, larger oil tanks, fans, drilled/tapped head oil ports, etc.

Sure,... at this point, it has been morphed into a,...

Freakin'-Screamin'-Top-Fuel-Burnin'-Arm-Yankin'-Fire-Breathin'-Nut-Bustin'-Thunder-Poundin'-Ground-Rippin'-Rooster-Shootin'-Adrenallin-Pumpin'-Hard-on-Makin'-Monster-Killin'-Butt-Puckerin'-Madman-Machine,.....

BUT !,...

The Reliability was left, back at the truck,
and is stored somewhere between the tools and spare parts, that will be necessary to have on hand, if the operator intends to be bangin' on it for all it's got.

There's even a few guy's who have fitted Turbo's or Juice bottles, but you can bet they dont go out on 50 mile rides with their buddies, and you can also bet they are carrying a towrope somewhere onboard the quad.
(with one end already tied to the FRONT bumper, and the rest coiled up for easy access)

This is all not even including, or considering,...
some of the stuff that goes on, in the "Hybrid's" crowd.

So as far as the "Bragging Rights" goes,...
It all comes back to the money you are willing to spend,
and how you define the bragging rights.

I define them as,
Every time it makes it back to camp ,

and ESPECIALLY when it does so,...
on the FRONT end, of the Towrope.
(mines NEVER seen,... the OTHER end of a towrope)

So there ya go,
as far as my generalized opinion,
of which, there are probably as many of those here, as there are,....
well,... you know. :devil:

Hope you and yours had a safe, happy , and very Merry Christmas!

[Wheelie]

I would highly recommend a stroker if money isn't an issue. Great power with little to no sacrifice in reliability.

I built my engine March of 06' and no issues to date, doesn't smoke and runs very strong. It hasn't had an easy life, it gets ridden hard, and maintained very well.

[Napalm Nate]

Has anyone used Duncan Racing's PC 4000 440cc cylinder kit. I know it is more expensive and you don't really need a new cylinder for a 440, just a bore and sleave, but in terms of reliability would it be a better choice? ( design & better head studs) just wondering they also make 450cc and 465 kits as well

[CJM]

Personally speaking I have been researching modding mine to be as powerful as possible while being as close to stock too.

I came up with the following:
450R carb
sparks key
exhaust/headers
sprocket change and or smaller tires.

For me since I ride trails pretty much, an exhaust and sparks key should do it for me. Maybe a 450R carb down the road, but I dont see myself needing more power than what I even have now. Also it helps to have a better handling suspension. I swapped to 450R shocks and it seems I can go faster b/c it handles better now!

I went from a zuk 230 to an EX and have been happy with just the stock power!

Its all really subjective. You can add hotcams, the sparks key, exhaust, carbs, big bores, etc. Bottom line is the closer it is stock the more reliable it will be. DOnt get me wrong, there are plenty of people who have modded and are happy and reliable, but its also how much you wanna spend. Shoot some spend more on the quad than the truck they put it into!