I have A Few 400Ex into 440Ex Questions

[BertPod]

I have a 07 400Ex that is starting to burn oil n other lil things,
I wanna do the 440 Big Bore Kit n Hot Cam Swap to it..

What is the Max Compression Ratio for Sunoco 93 Gas?
Could the 400Ex Carb be Jetted to support a 440?
What "Stage" Hot Cam would be best for this upgrade??

I dont race my 400ex, I dont even really ride it much.. But
when I do its a mix of everything.. Hills, Trails, BackYard Track..

Thanx,
Rob

[ish416]

I would recommend a 416 or 426 with 11:1 compression with Honda OEM XR400R gaskets. Any higher on the compression and you will be needing either E85 or a high octane leaded fuel. Also, the 416/426 make roughly the same amount of power and have the added bonus of running cooler.

The stock carb will be fine with a rejet but an 04-05 450R carb would make noticably more power than the stock carb and they are fairly cheap and easy to tune.

As for the cam, I would suggest a Stage 2 Hot Cam, as it's a great all around cam.

If you search around, you will find that combination is what most of the people on here run. It's proven, it's safe, it's relatively cheap and it makes for a fun ride.

[jman7290]

11:1 with 93' you can squeeze a little more compression out with an XR400 head gasket because it is thinner, but go OEM Honda for a good gasket. Stage 2 is the best all around cam in my opinion, the stage one is just to much low end and your shifting all of the time, and stage 3 is too much top end for the trails, good for drag racing!
You can jet your stock carb to work, but you would get more bang for your buck with a bigger carb. I would get a bigger oil tank, air shrouds, and a fan or secondary oil cooler to help with the heat that a 440 produces. I melted my first piston, but it was a Nurami! Go with an Wiesco or JE piston also. Oh yeah, you will need to install Heavy Duty head studs also, or you will be blowing head gaskets left and right. I found that out the hard way!!!

[JOHNDOE83]

when jetted right a 440 doesnt produce anymore heat then a stock 400ex.

I never got head studs or a oversized oil cooler and never had any heat issues, with a stock carb I was jetted at 210 for a main jet and a 42 pilot jet.

With my 450r carb I run a 220 main jet and a 50 pilot.

The mods I have are bigger valves, stage 2 cam, 440 bore, white bros rev box. Its proven to be very strong on the drag strip and MX track and very powerful for woods riding and technical stuff that needs bursts of power.

I would only recommend studs, bigger coolers and fans for high compression, which you dont want anyway.

10:1 or 11: you should be fine with sunoco 93, I cant remember if mine is 10:1 or 11:1 I run 87 octane to sunoco 110, sometimes I swear it runs better on 87 then anything else.

[DragonGunner]

Have had them all.....with a 440 you are running a bigger piston, I have found my 406 is much faster, lighter smaller piston revs faster and quicker. Take the $ you save from a big bore 440 kit, and get a 406 or 416 11:1 Wiseco or JE piston, and do a port job. just my 2 cents.

[jman7290]

It's a known fact that a 440 runs hotter, maybe not hot enough to ruin anything as long as you are moving. The cylinder wall is thinner and why take the chance, when you can have a cheap insurance policy that you have liability. John maybe your bigger valves help disapate the heat, but I guarantee you your bike runs hotter than a stock or mildly built bike...

[JOHNDOE83]

Using a infrared temp gun on multiple parts of the motor, my 440 runs at idle 190* on the cylinder and after a hard core 15min ride is about 260*. I would be willing to compare that to any stock or mild build temp reading.

Steve used to say the same thing until he actually owned and tuned his 440.

BIGG jetts are needed to keep a 440 cool, spal fan at most.

Unless your using higher compression.

Not having big enough jets is what makes a 440 seem slower and not rev as fast, once the jetting is right it will rev like a race motor should.

I would put money on my 440 winning a drag race over any smaller bore EX anyday and actually have.

[jman7290]

I wished you lived closer so we could line them up John. You might get your feelings hurt...

[DragonGunner]

Well right jetting is what you need for anthing....BIGGER jets to fit the build is always required so they are not running lean which makes heat, having a 440 has nothing to do with it...build a 406 with higher compression and more intake and you have to go BIGGER on jets also. I ran a 426 for a number of yrs. The cylinder wall is thinner on that than a on a new sleeved 440. It didn't seem to run any hotter, no problems, had BIGGER jets but thats not really what kept it cooler, just kept it from being too lean and running hotter. I ran 100 octane aviation fuel and that was probably the main reason IMHO that it probably ran so good, even after long rides and races, the higher octane burns slower relulting in less heat, at least guys smarter than me have stated...good fuel and right jetting is the key for any build to not run lean and get hot.

[JOHNDOE83]

Originally posted by jman7290
I wished you lived closer so we could line them up John. You might get your feelings hurt...



:D

[BertPod]

Waking The Dead Thread..

So Jus to ReCap...
440 With 11:1 Comp
And Stage 2 Hot Cam
Check

What Jets do I need??
Both Carbs 400ex and TRX450
(I wanna have Info for Both Carbs..)

[JOHNDOE83]

Waking The Dead Thread..

So Jus to ReCap...
440 With 11:1 Comp
And Stage 2 Hot Cam
Check

What Jets do I need??
Both Carbs 400ex and TRX450
(I wanna have Info for Both Carbs..)

Get jets from 190 to 220 in incriments of 5 like 190-195-200...etc.

chances are youll need the 220 and the rest will be a waste, but I highly reccomend having the extra jets. I couldnt even count the times i went to race and because it was either extremely hot or extremely cold i needed to change the jets out.

I ran a 210 in my stock carb and a 220 in my 450r carb with nearly the same mods as you.

Go here http://www.jetsrus.com/FAQs/FAQ_rejetting_101_how_to_rejet.htm and scroll down to the jetting procedure and read #4 labled main jet.

Start with 220 and see if it fully revs out, if it does leave the 220 and ride happy.

Also get a 42 pilot for a stock carb and a 50 for the 450r carb.