2000 400ex burning oil

[dmedal]

I just picked up my 400ex and after riding it for the first week i have noticed that it is burning oil at high rpms.

There seems to be no loss in power what so ever and the motor instantly starts cold with no choke or anything. When it is idling it does not smoke at all.

It is only when i rev it up that it starts to puff blue smoke out the exhaust. I have also noticed that i am loosing oil pretty quickly.

Any idea as to what the problem may be or what kind of fix i may be getting myself into ? appreciate your help...

[bwamos]

High RPM's "usually" points to worn rings. Fairly easy fix.

[Pojo450r]

if u notice alot of oil used then time for top end build but just check oil before every ride it should be fine for awhile my cousins does the same thing

[dmedal]

thank you both for your help. I found myself a compression tester and after a test found that the compression is at about 120psi which is well within spec. I am now starting to think that it is definitely the top end. Most likely the valve guides or seals.
I have also noticed that i am burning up to litre of oil every ride .... :ermm:

[my88r]

Originally posted by dmedal

I have also noticed that i am burning up to litre of oil every ride .... :ermm:

that's not good.:mad: let us know how you make out.

[bbender85]

yes, keep us posted... i just bought a 2000 400ex with the EXACT same symptoms and characterstics.

[below100hz]

mine was doing the same, ended up that i needed to get new intake valves and have the valves seats cut

[John451]

Yeah, guides are worn, its lettin oil down the valve and into the engine.

[dmedal]

I am taking the engine out tomorrow and bringing to a engine rebuilding guy he is going to tell me exactly what needs to be done. I will be sure to keep you all posted.

Oh and he when i mentioned the symptoms to him he said that 120psi was a relatively low compression for those engines .... according to the repair manual it is well within the 100 - 130 psi spec.

What is your compression like on your 400ex ?

Mine smokes when I ride it really hard and I am reving high racing. I compression tested mine at 110PSI and I am going riding today I switched to a thicker oil and I cleaned my air filter. Hopefully no more smoke.