New to here need help!

[Honda400rider14]

Hey guys I just picked up a 400ex yesterday and I believe it needs freshened up. My question is what do y'all recommend for top end rebuilding parts ?
As far as I know it's stock internals, but won't know till I get the cylinder to the shop. It's burning quite a bit of oil lol.
I would like to stay as far away from a 440 kit as possible !

[LxMxL97]

I would do a J&E 416cc 10.8:1 stage 2 HC kibble white valves and springs get new valve seals and guides and use some cometic gaskets to seal it all up stay away from weisco they're junk IMO

[BlasterEaten250]

I would do a J&E 416cc 10.8:1 stage 2 HC kibble white valves and springs get new valve seals and guides and use some cometic gaskets to seal it all up stay away from weisco they're junk IMO I agree with most of this, however I would would just go the next size up to 406cc. You won't notice any extra power with 10 extra cc's but on the other hand you will have that extra space to bore again in the future. Also, I have many, many hours on Wiseco pistons in a few different machines. They are a good piston in my opinion.

[400man]

i agree with above too. although ive never used a wiseco in a 4stroke yet, i used em in all the 2strokes i used to own, and wiseco was tops. im runnin a JE 10.8:1 in mine, been runnin great ever since.

your stock valves should be fine, just replace the valve seals. most people say cometic gaskets are king, which is what id use, or oem honda.

and if you wanna toss in a cam, a stage 1hotcam for low/mid and a stage 2 for mid/top power.

[Honda400rider14]

Where is a good place to buy a JE piston . I actually have a moose top end gasket kit with everything , and a oem timing chain. I've used cometic before, never had issues! I should probably invest I'm chain guides and tensioner right?
And 400man- I'm looking at stage 2 for the all around decent power. I'm just a trail rider who wants something durable and fun!

[400man]

i found the best price for my piston on ebay. and if you havent heard it yet, a good upgrade is to run a crf450 timing chain, just do a search on here for lots of info.

[Stickman400]

Best prices are gunna be on eBay for sure. Go with a Wiseco unless you want to spend the extra $ on a JE. Also make sure you get the MLS type Cometic gaskets, not the fiber material crap ones. And if you get a timing chain get new guides and check to see if you need a new tensioner.

[LxMxL97]

When I redid mine I used all the parts above but I forgot to mention that I put new a tensioner timing chain and new guides and I got my piston and gaskets for $275 shipped on eBay

[jcs003]

the best cheap upgrade is:

406 hi-compression
xr cam
xr timing chain
xr head gasket
and get the cylinder head freshened up with new components.

but if i were spending that i would send the engine to four stroke tech and have mickey build you a 440.

john

[DragonGunner]

I vote for a 406 11:1 wiesco, but have had a 416 with the JE, nothing wrong with that either. Once its in the shop they can tell ya if you need new valves or valve guides. I can't tell ya if you need a new timing chain or guides as I have a zillion hours on my 99' EX and it still has the the original timing chain and tensioner....it has been a 416, a 428 and a 440 and now a 406 and still going stronger than ever. So whats up with getting a new timing chain and tensioner....? Are the newer ones using cheaper less quality ones and they are breaking....?

[LxMxL97]

I vote for a 406 11:1 wiesco, but have had a 416 with the JE, nothing wrong with that either. Once its in the shop they can tell ya if you need new valves or valve guides. I can't tell ya if you need a new timing chain or guides as I have a zillion hours on my 99' EX and it still has the the original timing chain and tensioner....it has been a 416, a 428 and a 440 and now a 406 and still going stronger than ever. So whats up with getting a new timing chain and tensioner....? Are the newer ones using cheaper less quality ones and they are breaking....?

Preventative maintenece I figure if I've got it apart why not and I even put new clutches in my old ones were just fine but that's just how I am

[Honda400rider14]

Well a 416 piston should do the trick for me if it's not already bored out! This thing really has some power the way it is, even compared to my 450 ! But it's smokes to much for my liking.
A little off subject but does anyone have a headlight housing or rear axle and hubs up for grabs ? Someone welded the hub to the axle with rebar on this thing and the other hub is hella loose lol

[LxMxL97]

I've got a housing off of another bike but idk if it's even worth selling I'll have to check when I get home

[LxMxL97]

Mines off an 05-07

[Honda400rider14]

Oh crap lol. I got the older 2003 model

[LxMxL97]

Ok it's kinda rough anyway

[81dasher81]

a guy i know ran a wiseco.. he warmed it up, shut it down to cool off and started it up again and it sounded like a loose worn out motor.. turns out the piston shrunk 5 thousandths.. doesnt sound like much but its way too much.. they should only have about .001 of clearance. originally he thought the machine shop messed up, so he bought another piston to try it again and had the same result..

i would go with a CP or JE 406 or 416.. i run JE.

bumping up the compression will give you a little more snap, which we all know the 400ex needs lol

[DragonGunner]

a guy i know ran a wiseco.. he warmed it up, shut it down to cool off and started it up again and it sounded like a loose worn out motor.. turns out the piston shrunk 5 thousandths.. doesnt sound like much but its way too much.. they should only have about .001 of clearance. originally he thought the machine shop messed up, so he bought another piston to try it again and had the same result..

i would go with a CP or JE 406 or 416.. i run JE.

bumping up the compression will give you a little more snap, which we all know the 400ex needs lol


Sounds like the machine shop messed up to me. You get the piston and they bore and hone for that piston, and check it there. Never heard of a piston shrinking that much, it should have a tolerance and when warmed up expand, then shrink back to its original size. I've ran all Wiseco except for one JE and they ran perfect in every four stroke and 2 stroke I had. All pistons even of the same size can vary so thats why the builder should have the piston thats going in, so if he bought another piston and it was exactly the same and did the same, then the bore was too big......if its sloppy its the builders fault IMHO. But hey, sometimes strange things can happen, just never heard of this one.

[81dasher81]

Sounds like the machine shop messed up to me. You get the piston and they bore and hone for that piston, and check it there. Never heard of a piston shrinking that much, it should have a tolerance and when warmed up expand, then shrink back to its original size. I've ran all Wiseco except for one JE and they ran perfect in every four stroke and 2 stroke I had. All pistons even of the same size can vary so thats why the builder should have the piston thats going in, so if he bought another piston and it was exactly the same and did the same, then the bore was too big......if its sloppy its the builders fault IMHO. But hey, sometimes strange things can happen, just never heard of this one.

right, that's what he thought originally, even the machinist thought he possibly messed it up.. and yeah he gave the machinist the piston both times and tolerances were correct.. i'm sorry, i phrased that wrong, he bought another piston (and cylinder to bore) to try it again and had the same result, that was my bad. i thought it was crazy too.. needless to say he's sticking with JE and CP pistons now lol

[Honda400rider14]

Do I have to get a top end gasket kit according to the size of the bore I go with?

[CJM]

Do I have to get a top end gasket kit according to the size of the bore I go with?

No, not unless you have a 440. Piston never goes high enough.

[Honda400rider14]

No, not unless you have a 440. Piston never goes high enough.
Oh well what about just the bore size won't it be larger at the top too

[LxMxL97]

Do I have to get a top end gasket kit according to the size of the bore I go with?

I'm pretty sure you do but I'm not 100% sure that J&E kit I bought came with me cometic gaskets