blue smoke out of 400ex

[bbender85]

i got it. :ermm:

had the motor out the day after i bought it for paint. carb disconnected, oil tank drained, but NOT the crankcase... motor was on its side alot during the couple days it was out of the frame. i didnt ride it much before taking it out, but i'm sure it didn't smoke this much. has alot of wet soot on the exhaust tip. doesn't smoke too bad at idle, but rev it up and i have my self a smoke screen.

rings bad? any chance oil just got somewhere it shouldn't have during its time outta the frame and needs to burn out? anything else weird?

i havent had a chance to ride it and see if it uses oil, but until then i just wanna get an idea of all the possibilities.

[97WarriorRider]

Not to jack your thread. But mine uses quite a bit of oil. There is so blue smoke on start up and if you hold your hand behind the exhaust and rev it just a bit your hand will be black after a few seconds. whats that about? Sorry just didnt want to start another oil burning thread..

[UNBROKEN]

if the motor is warm when its burning oil when u rev and its still smoking id say its time for new piston and rings at least

Yeah if it smokes when its warmed up then you have some problems but on the start up and stuff you can see smoke and its no big deal. I see white smoke sometimes from a little water vapor in my silencer and things like that.

[97WarriorRider]

Mine doesnt smoke when its warmed up..just on start up..but if you put your hand behind the muffler even when its warmed up it will get covered with sooty oil

[400ex28]

Originally posted by 97WarriorRider
Mine doesnt smoke when its warmed up..just on start up..but if you put your hand behind the muffler even when its warmed up it will get covered with sooty oil

probably just needs new valve seals.

[REDRIDDER]

Originally posted by 400ex28
probably just needs new valve seals. and guides...guides are the likely cause of the problem when you first start the quad and it smokes but goes away but if the smoke continues you probably have a ring issue.

[Gibson]

mine does it on start up too, but when its warm it only puffs out blue smoke when i back off of it, so i probably have bad exhaust seals

[burnthesnikle]

mine smokes all the time:D

[UNBROKEN]

Originally posted by Gibson
mine does it on start up too, but when its warm it only puffs out blue smoke when i back off of it, so i probably have bad exhaust seals mine did the same thing and from wut i know it sounds like u need rings , id check the compression,

[97WarriorRider]

Originally posted by burnthesnikle
mine smokes all the time:D

hmm..wonder why..you might need new piston, rings, valves, guides, seals..lol..just pickin..I saw your sig..must be crazy fast

[bbender85]

alright, so i've had it out a few times now, and things are still the same; doesn't smoke bad at idle, but rev it up and it really puffs blue. warm or cold. it does idle just fine and runs good though.

but it uses a ton of oil. and it feels underpowered. i got beat by a bone stock 400, on moist sand... and i was running paddles. walked me hard. anyways.

i am thinking rings are the case. now the guy who i bought it from said (key word SAID... i'm finding him out to be shady) it was rebuilt less than a year ago, with an overbore; couldnt remember what size (apparently it was his buddy's when he helped rebuild, and he bought it shortly after). it's either a 1 or 2 mil over. SO.

if i want to do the rings, are there rings for each bore size, or are they compatible with the various bores? i ask cuz i'd like to order parts, then rebuild, instead of tearing down, checking the size, ordering/waiting for parts, then getting it back together. if thats not the case, so be it, was worth asking i guess, lol.

also i think there's a knock; again, i'm no expert, but it seems abnormal to me. if thats the case... will a rebuild kit with a piston fix that issue, assuming the knock is at the rod/piston interface?

thanks for bearing with me.. still new to me. :)

[2001trx400ex]

if its blowing the smoke when its warmed up the rings are bad and you need a new piston and rings had to do that myself

[bbender85]

Originally posted by 2001trx400ex
if its blowing the smoke when its warmed up the rings are bad and you need a new piston and rings had to do that myself


lol umm this post was from a year ago...


anyways, the thing was toast. here's some pics of the piston:






http://i154.photobucket.com/albums/s248/bbender85/quad/DSC03535.jpg
http://i154.photobucket.com/albums/s248/bbender85/quad/DSC03538.jpg
http://i154.photobucket.com/albums/s248/bbender85/quad/crack2.jpg
http://i154.photobucket.com/albums/s248/bbender85/quad/crack1.jpg

[UNBROKEN]

Originally posted by 2001trx400ex
if its blowing the smoke when its warmed up the rings are bad and you need a new piston and rings had to do that myself

dude this thread is a year old :rolleyes: