my 400ex is smoking

[UNBROKEN]

hey guys im new here and just traded my old yz400f for a 400ex so far i love it , but its smokes when riding, its burning oil im guessing its valve seals does anyone else have thses problems and it it okay to ride it, thanks,

[my88r]

its not okay to ride it like that in my book. you probably need rings. i would say do a compression test. if you do run it like that. make sure you always check on the oil. if its smoking blue you know its oil. if its black its running rich.

[byrdman]

does it smoke all the time when riding? mine smokes on start up and when it warms up it stops.

Normaly if its the valves it will mainly only smoke for the first few mins on start up and be blue smoke. Rings it smokes blue all the time and smokes worse as the motor heats up. If its rich it will smoke black.

[UNBROKEN]

it smokes when riding when i rev it up its fine but its when i let off the gas its smokes a little ive been checking the oil i think it got lower so ill be keeping a eye on that other than that it runs great, but u can put ure finger in the exhaust and see its just coated in oil, but the guy i bought it from was asking 1200 dollars its a 03,

[maxfior]

Depending on where you are located, now would make a great time (since it's winter) to pull the engine and rebuild it. Shouldn't cost you that much cash! Then in the spring you'll be ready to rip! At least, that's what I would do... Good luck!

Max

[UNBROKEN]

nah im not going to rebuild it manly because i need money for a truck i just wanted to make sure that i wasnt going to hurt anything i going to have it checked out soon tho , also one of the oil filter boltz were broken so should i drill it out or wut , right now it doesnt leak, knock on wood, thanks for ure help

[maxfior]

Originally posted by UNBROKEN
nah im not going to rebuild it manly because i need money for a truck i just wanted to make sure that i wasnt going to hurt anything i going to have it checked out soon tho , also one of the oil filter boltz were broken so should i drill it out or wut , right now it doesnt leak, knock on wood, thanks for ure help

I guess it depends on which bolt is messed up; you're going to want to keep an eye on that. If it is the tank bolt, you should be able to re-tap it maybe. Keep an eye on your oil consumption, I had an old XR250R that needed rings and I kept running it. One day I sort of forgot about checking the oil (guess I was young and stupid then) and it wiped out the cam lobs since it was starved for oil. If you don't keep an eye on it you'll blow the engine eventually. If the bore is okay, you might be able to get away with a good hone job and just toss a set of rings on your current piston and replace the valve seals. Shouldn’t cost more then a $100-$150 bones if you can install them yourself. Good luck.

Max

[KwAdUp]

i got my 400ex for 1200 too and it was blowing blue smoke and was knocking. but its most likely the rings. what i did was rebuild it with a 440 kit, stage 2 cam, new valves, and new cylinder head:devil:

[UNBROKEN]

the oil filter bolt that broke was the long bolt on the right of the filter, and i filled the oil to the top mark and in 1 hour of riding the bike was down to the LESS mark and when i got it wide opem in 5th after i looked at the pipe and it had fresh oil on the tip, so im going to have it checked out buy a friend, thanks guys

[UNBROKEN]

hey guys ive been busy but got word on my quad its neds top end and cylnder reboring the valves are trash piston and rings are trash and the head needs rebuilt thats just the motor end i wont go anyfurther on wut else it needs , parts 319 + 85 for cylender reboring and labor im not sure yet, so my question is if i go with a high compression 11 to1 piston will i have any issues reliablity wise, or bore it to a 416 will i have any issures with durabiltey, thanks alot guys

[UNBROKEN]

hey guys ive been busy but got word on my quad its neds top end and cylnder reboring the valves are trash piston and rings are trash and the head needs rebuilt thats just the motor end i wont go anyfurther on wut else it needs , parts 319 + 85 for cylender reboring and labor im not sure yet, so my question is if i go with a high compression 11 to1 piston will i have any issues reliablity wise, or bore it to a 416 will i have any issures with durabiltey, thanks alot guys