just got her

[RustyStunts]

got it from a insurance auction...front bumper and rear grab bar were bent up and some other little things but i got to ride her as soon as i unloaded...it has a full pipe and a big gun rev box it is im guessing ( im sorry i dont know much about this kind of stuff) but im wondering if it could have some motor work done how can i find this out for sure??

[RustyStunts]

iiiiiiiii

[bigbad400]

i know stickers dont mean much but weiseco is pistons and hinson is clutch components, so it could have them. the only way really to find out is to start tearing it down. i would leave it alone myself. at least untill you want more power or you broke something.

[jasonwayne222]

how much u pay

what year

[RustyStunts]

i payed 875 for the quad..its a 2002 salvage title

[400excracer]

Congrats! Good deal.

[bkelley]

Originally posted by bigbad400
i know stickers dont mean much but weiseco is pistons and hinson is clutch components, so it could have them. the only way really to find out is to start tearing it down. i would leave it alone myself. at least untill you want more power or you broke something. Yeah, judging by the stickers, air shrouds, 450r shocks and whatnot it's probably got something done to it.

[IRISH-RACER-14]

theres that big wiseco decal on the side. that mite show that the quads got some head work done. and its got a rev box..u dont just put a rev box on a stock engine.

[johnnynonails]

sorry guys,but there only stickers u can get them anywhere,simple answer is have a look inside the motor and see what it had

[RustyStunts]

well i took the quad out today and HOLY COW was it fast!! it smokes a bit but oh well dont bother me...she revs much more then my stock 400ex and pulls like a 2stoke once it gets up their on rpm's....

[Chuck75]

Hell for that price who cares whats in it. you could part it out and damn near double youre money. I got dibs on the exhaust:D

[bkelley]

Originally posted by johnnynonails
sorry guys,but there only stickers u can get them anywhere,simple answer is have a look inside the motor and see what it had No one is saying it has something done just because it has cool stickers. I was saying that the chances are pretty good that something has been done to it since it has some other aftermarket mods done to it (450r shocks, air scoops, etc.) and I can only assume that they broke into the motor as well. Obviously the only way to know for sure it to open it up.

[RustyStunts]

yea the quad is super fast im guessing it has motor work done..i just bought a top end gasket set so m gonna put all that on see if she doesn't smoke

[Rscarpantonio]

if its smoking ( out the exhaust im gussing you mean) it wonlt mean S*** putting a new top end gasket on it, you need new rings and a hone done

[RustyStunts]

Originally posted by Rscarpantonio
if its smoking ( out the exhaust im gussing you mean) it wonlt mean S*** putting a new top end gasket on it, you need new rings and a hone done yea I know but I'm leaking some stuff out the head gasket so that's why I bought that kit...what my prob is now that I don't know what size piston is inside..I don't wanna take it apart and have it sit as I wait for parts...but I guess I gott tear it down and find out what's inside

[mineralgrey01gt]

Originally posted by RustyStunts
yea I know but I'm leaking some stuff out the head gasket so that's why I bought that kit...what my prob is now that I don't know what size piston is inside..I don't wanna take it apart and have it sit as I wait for parts...but I guess I gott tear it down and find out what's inside

get a dial and see what size it is. Then again it may not have much done because that sure looks just like stock plastics to me, not Maier like it says on the sticker. Let us know whats done to it if you find something. I went through the same thing with my 400ex, guy told me it was a 406 bore on it, bs, it was bone stock and it had a bunch wrong with it, gear selector was loose causing it to jump out of gear and the carb needed to be cleaned, ran good then i took it down to see why it smoked and it was the original piston still in the bike, and it had a blown headgasket

[RustyStunts]

wow so i took this 400ex out today to a long parking lot to mess around...i also brought my 05 450r along...me and my buddy raced back and forth and this 400ex was taking the 450 every time...i couldn't believe it so we switched quads and still the 400ex pulls on the 450r every time...i was shocked...it must have motor work done to beat a 450r..and my 450r has one down on the front sprocket and yet this 400ex pulled of the line all the way down...

[RaceinCircles]

I put a bid on this quad too ;) l decided after all of the fees that came with it, it wasn't worth it... Should be a fun build though!

[RustyStunts]

yea it came out 1030 even..i think thats worth it..quad runs good

[rob_990]

if the head gasket is blown you might be running a high comp piston and youll probably need to put in some gtt head studs or its just gonna keep blowing.

[jessebs]

great deal on that quad man!

[tri5ron]

The only way for a 400ex to keep up with, and beat a good running 450r is with a big bore, high compression piston, big cam, piped, and jetted. Period.

Since you say it will beat a 450r, and it is leaking at the head,...

I'd bet $100 bucks that it has a 440 12:1 piston,(or higher), big cam, never had the HD studs installed, has been over revved, and the studs are pulled out of the cylinder threads.
You are describing ALL the classic symptoms, and it is literally running on the razors edge of grenading itself.
Your engine is going to blow very soon, without doing the proper overhaul which, at MINIMUM, includes, HD studs properly installed BY A MACHINE SHOP, a new piston, rings, hone job.

that's just the facts of life with a improperly, over built, 400ex engine.

[RustyStunts]

yes great post tri5ron!!!! Everything I said was true..I also have a yfz450 and know for a fact my 450r is faster by just riding them..like I said my buddy bought my 450r brand new and babied it the hole time he had it so I'm pretty sure it's run good for being bone stock besdies having one down in the front....and I'm sure your right about the 400ex but I have no idea how to find out what's inside...I'd like to redo that motor but have no clue who could do the work around here...

[RustyStunts]

and would the carb not having a choke on it have enything to do with this???

[tri5ron]

Originally posted by RustyStunts
and would the carb not having a choke on it have enything to do with this??? No. Not enough to matter.


It sounds to me, like it was built up by someone who did not know what they were doing in reguards to hopping up a 400ex engine.

All the kids,
who want all the "Go fast" stuff,
generally jump straight to a big piston, cam, and rev box, before doing any homework on the subject.
They usually go for the cheapest way to accomplish that, and/or, dont have, or want, to spend the cash to do it the proper way, which always results in the exact situation that you now have.

again, that's just the facts of life with a 400ex.

You have a solid machine there, that can give you many years of reliable service, if you are willing to DO IT CORRECTLY.

Since you already have a 450r, and a yfz450, for "Go Fast" bikes, you should seriously think about rebuilding the 400ex more towards a nice solid trail/woods/xc machine.

This means, drop the piston back down to a 400, 416 or 426. You may ALREADY need a new cylinder anyway. If so, then suck it up and get one.
Get a piston with no more than 10.5:1 compression, and use a cam with either a stock grind, or something similar to a HC stage 1.

Lose that rev box too.
All it's doing for you is,...
It's going to blow your motor sooner, and you do not need it.
The 400ex makes it's max power curve, well before the stock rev box hits the limiter.

There are still some respectable gains in power to be had, over the stock configuration,
while maintaining all the original reliability of the stock 400ex.

You already have a higher flowing exhaust, and intake. Those are fine.
Add a properly tuned 450r carb to it, and a timing advance key if you so choose.
Neither one of those will hurt anything, and are proven to provide respectable gains.

If you do these things described, you will have a near bulletproof machine, that is putting 32 to 37 HP to the ground, (stock is about 24 hp), and will basically run forever,...AND, it will never see a tow rope tied to the front bumper.

It will be the machine, that not only keeps up, (or nearly enough to not matter), with everyone else's machine,...
and it will ALSO be the machine, that tows EVERYONE ELSE'S bike back to camp.
Add to that,
It will also,... be doing so,... on straight pump gas,... with NO OVERHEATING ISSUES.

If you continue to ride you bike in it's current configuration and condition,....
I highly suggest you don't go any farther away from camp,...
(without a tow rope already tied to your FRONT bumper),...
Than you are willing to push it back.

and that's just the way it is.

[RustyStunts]

Originally posted by tri5ron
No. Not enough to matter.


It sounds to me, like it was built up by someone who did not know what they were doing in reguards to hopping up a 400ex engine.

All the kids,
who want all the "Go fast" stuff,
generally jump straight to a big piston, cam, and rev box, before doing any homework on the subject.
They usually go for the cheapest way to accomplish that, and/or, dont have, or want, to spend the cash to do it the proper way, which always results in the exact situation that you now have.

again, that's just the facts of life with a 400ex.

You have a solid machine there, that can give you many years of reliable service, if you are willing to DO IT CORRECTLY.

Since you already have a 450r, and a yfz450, for "Go Fast" bikes, you should seriously think about rebuilding the 400ex more towards a nice solid trail/woods/xc machine.

This means, drop the piston back down to a 400, 416 or 426. You may ALREADY need a new cylinder anyway. If so, then suck it up and get one.
Get a piston with no more than 10.5:1 compression, and use a cam with either a stock grind, or something similar to a HC stage 1.

Lose that rev box too.
All it's doing for you is,...
It's going to blow your motor sooner, and you do not need it.
The 400ex makes it's max power curve, well before the stock rev box hits the limiter.

There are still some respectable gains in power to be had, over the stock configuration,
while maintaining all the original reliability of the stock 400ex.

You already have a higher flowing exhaust, and intake. Those are fine.
Add a properly tuned 450r carb to it, and a timing advance key if you so choose.
Neither one of those will hurt anything, and are proven to provide respectable gains.

If you do these things described, you will have a near bulletproof machine, that is putting 32 to 37 HP to the ground, (stock is about 24 hp), and will basically run forever,...AND, it will never see a tow rope tied to the front bumper.

It will be the machine, that not only keeps up, (or nearly enough to not matter), with everyone else's machine,...
and it will ALSO be the machine, that tows EVERYONE ELSE'S bike back to camp.
Add to that,
It will also,... be doing so,... on straight pump gas,... with NO OVERHEATING ISSUES.

If you continue to ride you bike in it's current configuration and condition,....
I highly suggest you don't go any farther away from camp,...
(without a tow rope already tied to your FRONT bumper),...
Than you are willing to push it back.

and that's just the way it is.

sweet well i guess its time to take the camera out and start tearing down!!!! i work at a precision cnc machine shop so im going to take the motor apart and measure everything out at work and post it here...then ill know where to start buyin stuff atleast...

[xcracer416]

i will chime in on this and most will agree with me on this, if it has a big bore and your going to keep it big bore with a decent amount of compression i would recomend gettin and using a cometic topend gasket kit for any 400ex big bore. that and the head studs will keep you from wrenching on the head gasket frequently.

the cometic gasket set should be the only one offered for a 400ex in my opinion.

pus if it needs rings i hope the piston has identification marks on it. rings for a JE are thicker than wiesco. pics might help out.