400ex motor rebiuld/or buy new3 motor?

[p0opstlnksal0t]

well i messed up the motor i have in my 400 right now... i was rappin her out and when i shifted into 4th from third she just died... had to pushe her home, then tried to jump start her in the driveway, and heard a clincking noise, but when just cranking it from the battery there is no noise. while cranking from the electric start, every once in a while the motor would backfire... im positive i f*kd up somthing major internally. now i dont know if i would be better off buying a used biult up motor in the classifieds, or taking mine to a shop, and getting it rebiult. any input? should i just buy used but good condition modded motor in classifieds, or would i be better off taking mine to a shop, and getting it rebiult?

trey

[Chino886]

based on your profile you are 20 yrs old, that means you should be able to tear into the motor to see if anything is wrong....just get a manual and start wrenching, will save you a ton of money...

[p0opstlnksal0t]

jus dont got the tools, or space to do it... i could if i lived with my parents... but i cant just rip this thing apart in the parking lot of my apartment. lol

[DAVE14]

need more info but if it died while runnin & doesnt run now & backfires it sounds like a timing chain/valve type of problem get a manual & take off rockercover then , head & you should see what happened it definitely sounds like top got smacked ,try a compression test & have someone a little more experienced see what its doin before takin it apart.

[DAVE14]

ide find a place to do it at a friends or family etc. theres enough people on here that have done countless rebuilds & could walk you through it no problem , otherwise prepare to bend over !

[p0opstlnksal0t]

crap.. forgot to mention.. when i bought the quad it ran beautiful... about the 5th ride out was when she broke... i checked the oil in the res. and it was full (almost about to overflow....) then i pulled the engine oil drain bolt.... nothing came out??? i should prolly get a repair manual... but this strck me as odd... dunno i kinda figured if the oil in the resevoir was full.. it woulda leaked out of that drain hole??? thought maybe the oil went dry in the crankcase, and prolly spun a piston rod bearing er sumthin???

taking a compression reading on the cylinder would be easy except the fact that none of my fathers deep sockets would fit on the spark plug... wtf... its like it has a lip around the plug on the top of the head that will only allow a special bought socket to fit. i might be able to rip the motor down somewhere, problem is i have the knowledge, but not the patience or skill to fix it... i used to rip my dirtbike motors apart to replace the topend, and would always *** up somehow.. then i would end up taking it to a shop in the end! lol

[Chino886]

patience is a virtue....or you could spend some cash and have someone do it....not the dealer...take it to a shop around you area...

[p0opstlnksal0t]

i just think it might be better to spend like 800.00 on a used good condition modded motor, then to spend more than that to get mine rebuilt (depending on damage)...

dunno, maybe ill take her to a friends house this weekend and strip the motor down... see whats going on in her!

[Chino886]

I think that is the best idea, could be your valves or something as simple as cam chain...

[CDCHONDAS]

I'd also look a simply shearing a flywheel key, Being on the other side of the fence and working on other peoples stuff everyday please if you tear it down with any doubt of you being the one putting it together, organize the parts in a decent way because nothing is worse than making a motor out of a box of parts. if you are looking for a shop in your area ask around to find someone reputable because I know through all of my advertising it means nothing if someone gives me a bad rap and tells his buddies, someone will be able to point you to a good shop from word of mouth advertising

[ill_lil_romey]

I had a similar problem with my 400. The motor just seized in the middle of a race, turns out something got into the motor and locked between the piston and cylinder. It's doubtful that this happned to you, but honestly the ex motor is not hard at all to work on. Get a clymer manual and dive into it. The key to setting things up right is organization. Make sure you keep your bolts and whatnots organized when you disassemble. Even if you can't put it back together you will save a ton of money diagnosing the problem yourself, buying the parts, and then maybe going to the shop.

[p0opstlnksal0t]

we'll see...

i dont even know if ima have time to rebiuld it... id rather just buy a used motor, and replace it, rather than to take it to a shop and waste money on labor.

lemme do a search, and see if i can find a thread about rebuilding this motor... see what all its gonna involve.

[Chino886]

on the 400ex, a topend rebuild basically consists of a piston and rings....that is if the cylinder bore is still good....you can replace the cam while you are in there.....get the valves checked.....cam chain replacement.....that is basically you simple topend rebuild....

The bottom end....now that is Greek to me.....:eek2:

[sickmojave]

Originally posted by p0opstlnksal0t
id rather just buy a used motor, and replace it,


If you buy a used motor you may just be buying someone elses problems.. I would just get a manual and see if I could fix it myself..



The bottom end....now that is Greek to me.....

if you're good at paying attention to details the bottoms not any harder than the top

[Chino886]

Well, I have done the clutch side (replaced the basket, pressure plate), but the flywheel and splitting the cases is just something I don't want to do.....but I am going to have to....

Hey StinkyPoop,
My best advice is to read the manual a couple of times before you dig into it, if there is anything you don't understand, ask first, before you get started....

[p0opstlnksal0t]

preciate da help yall...

ima prolly dig into her this weekend.

[bwamos]

If you're gonna scrap her anyway.. what is it going to hurt to rip it apart? :)

Worst case, there's a lot of damage. You take the rest of the undamaged parts and e-bay them to help pay for the new motor. ;)

1 Gallon Freezer bags are your friend. ;) Get the one's that have that spot you can write on. ;)

[DAVE14]

ya might as well look & see whats goin on it could be an easy top end job to do a comp. test youll need a very skinny 18 mm. socket I grinded one down for my plug buying a used motor without knowing its real history or if its been built or built correctly can put you in the same position youre already in.

[p0opstlnksal0t]

Originally posted by DAVE14
ya might as well look & see whats goin on it could be an easy top end job to do a comp. test youll need a very skinny 18 mm. socket I grinded one down for my plug buying a used motor without knowing its real history or if its been built or built correctly can put you in the same position youre already in.

thats the main thing im scared of...
thats why im leaning more towards rebuilding my current motor... at least ill know its done right if i do it! and it will be brand new.

[p0opstlnksal0t]

can any1 point me in the direction to an online repair manual or something similar

[Chino886]

Originally posted by p0opstlnksal0t
can any1 point me in the direction to an online repair manual or something similar

I don't know of anywhere online where you can find one....I think you will have to buy one or try your local library....

[p0opstlnksal0t]

i got a honda powersports dealer near me... ill see what time they close, and get a manual

[Chino886]

money well spent in my opinion....

[44oEX]

I pm'ed you

[p0opstlnksal0t]

Originally posted by 44oEX
I pm'ed you

u 2

[bwamos]

I have a Honda Service Manual, and a Clymers. When I'm working on the motor I have both out. One will usually have some good info that the other wont have.

[p0opstlnksal0t]

do they sell clymers repair manuals at honda powersport dealers? or are they some other kind of repair manual? which is better?

trey

[ill_lil_romey]

Most all dealers will have repair manuals. If you cant fine one go to www.rivaracing.com and use the microfich diagram, everything goes back on the direct opposite of how it came off.