I bought my 2001 400ex 1 month ago. My riding buddy bought one the day before. Both were properly broken in, never romped on or raced, and always had proper fuel and oil. The second time we had them out they were blowing slight blue smoke. We were told this was a good sign that our motor was breaking in and the oil was simply breaking down. Sounds good. After the oil was changed the next time we rode them, still smoking. After talking to our dealer he said to bring them in for a valve adjustmen, under warranty, it did not help. Now they still smoke and the salesman is trying to say it is the accelerator pump pupming too much fuel. That is B.S. . Fuel smokes black, water white, but the blue smoke we have is oil. Not? I assure you both are well maintained and ridin responsibly. PLEASE REPLY WITH ANY QUESTIONS OR SUGGESTIONS.

 

ensure that your oil level is correct.... sometimes when you check it, you wait till it is too cool, and you get a lower reading... if it is abouve 55 degrese F, the let it war up for 5 min (idle, occational blip of throttle), then let it cool for 2 and 1/2.

Also if way to much oil is being used then you might blow a gasket, look for that too to make sure everything is ok.

good luck!

 

This has been covered many times, the 400 engine runs very hot and breaks down oil very quickly. They all do this.

Run 20w50, your smoke will go away. I run Mobil1 15w50 synthetic (for many reasons, if you would like a breakdown, do a search, if you can't find anything, e-mail me). When running conventional 20w50, I could get probably about 4 hard tanks of gas through before it would start puffing smoke. With the Mobil1 I could go much, much longer. I have made a believer out of several folks with smoking bikes as well, including a heavily smoking '99 model of a close friend. Give it a try, your 400's trying to tell you something....

 

Humm... mine doesn't

 

That is not true that all 400EX's smoke. My buddies doesn't at all. Mine did. It started smoking worse so I took it apart and noticed (with the help of someone qualified) that the oil rings on my 400EX were shot and damaged my cylinder walls (probably from sucking in sand at Little Sahara through my faulty rubber boot). Now I put in a Wiseco pro lite piston .040 and it doesn't smoke once again. Now alls well.

 

Ever ridden behind your bike when it was being ridden hard? You may not have noticed it. They do it on deceleration when hot after turning lots of Rs during hard acceleration. I have noticed it on a few bikes that the owner's claim don't smoke too. Mine started around the 3rd tank of gas, it was in August of last year, it was bone stock, broken in properly, and ridden in low dust conditions. I changed the oil with 10w40 (which I am told is what the factory fill is), it stopped for about 1 tank, then started again. I switched to 20w50, it stopped for a while. Then I switched to Mobil1 15w50, hadn't had any smoke for months, then added my K&N filter, now I have real problems.

I ride with a buddy that has a 2000 XR400, after it gets hot, his will do it too, especially when it's getting close to oil change time.

Probably noticed at least 50 400EX's that I have ridden with doing this to varying degrees.

I bet your's does, whether you realize it or not. Do a little test: go out, ride it very hard for at least 30min - 1hr, lots of engine load, lots of WFO throttle, get it nice and hot... Then stop, put it in neutral, free rev it to about 7-8K 3 or 4 times. If you run conventional 10w40 or lighter oil, chances are, you will see smoke as the engine comes down. If not, you are a very small minority.

I believe "Santa" on this forum has taken my advise on the subject and his problem mysteriously disappeared like mine did and the others I have convinced to switch. Do what you want, the problem is real, go to any riding area or race, watch (or better yet, ride behind) the 400EXs, you WILL see and smell oil smoke. Do a couple of searches on the topic, many people here have had the same problem, when they drained their oil, it was water thin (broken down to it's base stock). The EX breaks down oil quickly, the smoke is the result.

 

Thank you to all who replied. Talked to my dealer today and he said to run 20-50 and if it doesn't cure her they will ring it. He also said i could have the ring gaps lined up, (so oil is going right up), or that i could have a scraper ring in upside down.THANKS I'll try and keep you updated.

 

Let us know... I was almost to the point of taking mine back after laying down my $5600 for my first brand new ATV. But I had real problems allowing the dealer to open up my brand new engine, a lot of times, you are opening yourself up to more headaches.... Then I began to think of the pattern of what was happening & what I'd seen on others 400s. It all began to come to me, so I changed my oil viscosity - problem solved...

Good luck & remember that the 20w50 conventional oil will break down too, just not as quickly.

 

Try Honda oil, regular motor oil breaks down at a lower temp. They say its the same but is not. My 00 xr100 smoked blue smoke for a while until I tried the honda oil. just a suggestion. Give it a try.

 

Gabes right ,Mobil 1 15-50 synthetic is the only thing I run since broken in.Never a puff of smoke.My buddies 99 400 used to smoke until he switched,not any more.Conventional oils break down way to fast in these high strung atv,motorcyle engines,plus some of you guys should get in the practice of changing you oil and filter more often,like every 4 rides or 20hrs,especially if you get on it,if cruising trails then every 5-6 ride or 30 hrs should be sufficent.