rebuild 400

[unlucky13]

ok my name is chad im 17 and dont have alot of money i traded for a 400ex that was tore down or i was told had a new bottom end and that he was gonna mail me the new jug and piston and never got it so im tryin to rebuild it myself so what is the easiest way to get the piston jug a new timing chain and new vavles in?

also i have a edolbrock carb for sale along with some other parts

[chronicsmoke]

welcome to the site!

Sorry to hear you got bit by a low-life seller..

Check E-bay for the parts, unless somebody in the classifieds section has a complete top end for sale..

There's alot of guys here that REALLY know their stuff, so if you have any questions, just ask away! (preferrably in this thread!) lol

Good Luck!

[ridehonda400ex]

Well how tight is your budget is a good question?

I would use ebay to get a jug. Then get a piston for a 402 or 406 bore, You can go bigger if you want. And get a higher compression, 10:1 or 11:1. Then get it bored to match the piston.

For timing chains-get the 2002 crf450 timing chain, its strong and is a perfect fit, usually around 45 dollars

Valves-Kibblewhite, or OEM

And if you get the extra money get a pipe for sure and a cam would help alot too.

[DnB_racing]

and get a service manual!!

[woodsracer144]

Originally posted by DnB_racing
and get a service manual!!

amen to that!

[unlucky13]

Well I picked up a complete used motor with a fried bottom end bearing took the jug and head off of it the jug looks like it just needs to be honed which I was told was about $25 needs 2 ex valves and I work at a grocery store so it's a small budget im thinking bout oem piston crf timing chain oem valves and 450r carb I have a fg krome full exshuast system anymore ideas? Thanks for all the input guys

[CJM]

Be sure to check the bore and measure it to make sure its not egg shaped.

[unlucky13]

alright my local shop should be able to do that right? and whats the cheapest but best brand to go with when goin with valves and piston and cam chain?

[unlucky13]

i was wonder what it would do if i put a 450r fan infront of my air cooler?

[tri5ron]

welcome to the forum Chad,

by reading your post's it appears to me that you do have some knowledge and a little experience in engines and possibly rebuilds.
Kudo's to you for wanting to do as much of the build yourself.

First off, I second the suggestion for you to get a Factory Service Manual.

Ebay, and some patience, is going to be your two best friends during this budget minded build.
I COMPLETELY understand the need to spend as little as possible, but I also think that you probably understand that doing it wrong, will inevitably end up costing more,.... than doing it CORRECTLY the first time.

OK, here's a couple of things to consider...

you are saying that you will probably go with a OEM piston. But you are also saying that you have a used jug, and are willing to pay to have your local shop measure it.

The OEM piston from the dealer is probably close in price to a aftermarket 416 @ 10.5 : 1.
So why have the OEM piston ?
then with that train of thought, you don't spend the money, to have them measure a old used jug. Instead,... You use that money (+ a FEW, but not much, dollars more),... to have them bore that old jug, into a new perfect fit to your new 416 piston.
The difference in price will not be very much... And you will have BOTH, the peace of mind knowing it is a clean - tight - perfect fit,... as well as,... a better running combination.

The CRF Chain is a top choice, and you already said you are going to buy that.

You already have a full exhaust, and you are talking about getting a 450r carb.
All SOLID choices, and a OEM piston would only hamper the performance, of those combined parts.
So it really just dosent make any sense to stat with the OEM piston, if you are going to be buying a new piston ANYWAY.

A 416, @ 10.5 : 1 compression, does not produce an excessive amount of heat, and it will still run on "Pump gas" just fine. you can still run the stock cam just fine,... (or you could go to a stage 1 if you choose to do so).
It will have just as good of reliability as a bone stock engine will have,... and it will run TONS better.

You have already demonstrated a above average intelligence in the fact that you are doing you "Research" here, before spending your hard earned cash.
there are alot of very sharp guys here who are willing to help and will assist wherever you need it.

I'm just suggesting that you do the comparative shopping between the price of a new OEM piston/rings/gaskets, etc.. from the dealer,...
as opposed to,
A good aftermarket kit,...

... and keeping in mind, of the best way to get the most out of your current, and future performance parts.

As for your question on the 450r fan, Just do a Spal Fan, instead of the 450r fan, and you will be fine. It is a very popular and budget minded upgrade.

Good luck in your build, whichever way you decide to go,...
and again,...

Welcome to the forum.

[unlucky13]

I have a stage 2 cam would that be alright with 416? And I can buy oem piston rings pin clips and two valves for 181 and one of my friends own the local shop so no charge for checking it out and what's a estimate for the fan ur taking bout?

[tri5ron]

OK,... you are starting to jump all over the place with this build. and the proposed "budget".

You have to decide what you want this engine to do,...
How you will REALISTICALLY be riding it,...
What your preffered riding style (AND SKILL LEVEL IS),...
What your expected level of Reliability is,...
What your "Maintaince, Upkeep, and Repairs Budget" will be,...
And what your Priorities are.

You can not put a stage 2 with a stock piston, or any piston that is around the stock compression ratio... and expect it to run worth a damn at all.

The choice of cam has more to do with the Compression ratio, than the bore size.

If you are going to use a stage 2 cam, you should be at a MINUMUM 10.8 : 1 ratio, or otherwise you will lose alot of your bottom end torque.

BUT,... you must ALSO remember, that with more compression, comes more heat.
More heat requires more cooling.
(ESPECIALLY on a air cooled engine like the 400EX). i.e.- more cost
More compression ALSO SHOULD BE accompanied with HD studs, (even more cost)

I think the Spal fan that most of the guys use is the 5.5" puller, that can easily be found on ebay for around $35.

Please don't come back and say, that you are also going to buy a Monster coil,... CDI over rev box,... iridium spark plug,... magnetized fuel line,... red power bands,... hyperspace flux capacitor,... mini tornado intake vane,...removed the choke,... install the Boyesen Power Wing,... 2" wheel spacers,... flipped rims... titanium fuel vent cap,... billet brake line bearings,.... Willie Wonka Chocolate transporter,...

...and you want to beat up on the Big Bad 450r riders....

if you do that,... I might have to take back my previous complimentary references.

:huh

[unlucky13]

I didn't buy the cam stage 2 cam and stage 3 cdi box came with the bike when I got it my friend has a 450 and I know for a fact im not gonna out run him but I would like to not get eat up as bad I don't want alot of maintanice I am really not sure what I am wanting to do I live in th country alot of gravel roads and trails and you can ride on the highway around here so I want something I can pin for sways without it melting down but wanna keep it cheap in a way bc I will be Layin someone to adjust my valves and timing I also have a edolbrock carb that came with it to

[tri5ron]

Originally posted by unlucky13
I have a stage 2 cam would that be alright with 416? And I can buy oem piston rings pin clips and two valves for 181 and one of my friends own the local shop so no charge for checking it out and what's a estimate for the fan ur taking bout? My last reply, was in response to the above statement where you said you already had the stage 2 cam.

As I now realize, that you need to first figure out what you want, what you can and can't have, what you can spend, and what your priorities are,...

I again wish you the best of luck in your build.

[unlucky13]

Ok well would you help me here I want something that's low maintace I will be able to run pump gas (maybe a little octane booster) something I can throw a fan on and it run cool but still be able to use 450r carb hc 2 and cdi unit what would you be thinking on this? Thanks for all your input

[tri5ron]

Originally posted by unlucky13
Ok well would you help me here I want something that's low maintace I will be able to run pump gas (maybe a little octane booster) something I can throw a fan on and it run cool but still be able to use 450r carb hc 2 and cdi unit what would you be thinking on this? Thanks for all your input In trying to maintain patience, and give solid advise here,...

First and Foremost, buy a Factory Service Manual.
Read it.
Then read it again.
Get intimately familiar with it.
Then read it again.
Sleep with it under your pillow.
Then read it again.

Start reading as many of the threads as you can find, that covers questions you may have.
Archived threads are your friend.
Then read your manual again.

For a Budget Minded - "best bang for your buck" build,...
with Low maintenance, High reliability (no excessive heat issues), and running pump gas (91-93 octane) as the Priorities,...

416 piston, with your cylinder bored to PROPERLY MATCH YOUR SPECIFIC PISTON
10.5 to 10.8 :1 compression ratio
HC stage 1 cam
'02 CRF 450 timing chain
Cometic gaskets
stock OEM valves
Sparks +6 key
'04-'05 450r carb - PROPERLY JETTED
UNI airfilter w/ Outerwears
5.5" Spal PULLER fan, (if you so choose)

If you already HAVE a full exhaust system, then use it.
BUT, if you "Have Not Yet" bought it,... then don't waste your money.
Instead, grind the head pipe welds on the OEM headpipe, and pick a slip-on of your own choice. (btw- more volume and excessive Db's,... DO NOT EQUATE to more power).

Next,... get rid of that P.O.S. rev box, and replace it with the stock OEM rev box. If you doubt that, look it up. it does absolutely nothing for any 400ex, other than a full blown, radically built, stroker motor.

After you get done with all of that, install some decent upgraded front shocks.
They will do just as much for you to improve the performance, (and your ability to ride faster), than all the above listed modifications to your engine.

[unlucky13]

i got a manual that was the first thing i got and i am wanting to save some cash and use my stage 2 cam so i was wonder what a 416 pr 426 11:1 would do? i found where i could get a 416 11:1 bore with a cp piston and could you explain the +6 key?

[tri5ron]

Originally posted by unlucky13
i got a manual that was the first thing i got and i am wanting to save some cash and use my stage 2 cam so i was wonder what a 416 pr 426 11:1 would do? i found where i could get a 416 11:1 bore with a cp piston and could you explain the +6 key? There you go again,
bouncing around all over the place.
First you said you have a stage 2, then you said you didn't have it, now you again imply that you do have it.
Then, you jump towards higher compression questions, when it's already been stated as to WHY you should be avoiding it.
Could it be ...
The related costs? reliability? heat? fuel? maintenance?
Hmmmm, I wonder ?

You asked for a build list for a Budget Minded build, That is Reliable, Low maintenance, Runs on pump gas, and Will Not get too hot.

With those as your priorities,...
I've given you a SOLID build list, that will run very strong, not require an excessive amount of maintenance, will run on pump gas, and will not get too hot.... Yet WILL still produce around 35 Hp.

Notice, that it Does Not include a Stage 2, OR 11:1. (you guess why) related costs? reliability? heat? fuel? maintenance?

Your priorities, budget, and desires, apparently are not in sync with each other.
You'll soon be here, asking questions, as to why you have Leaking oil, Blown head gaskets, and Pulled out head bolts.

lots and Lots and LOTS of good information can be found right here...
http://www.exriders.com/vbb/showthread.php?s=&threadid=464998

I'm done

[unlucky13]

Does anyone know if a 450rswingarm will fit a 400? And as far as that goes im trying to use as much of my parts I already have here is what I have stage 2 cam edolbrock carb aftermarkey cdi and full ex system