Jump to content

  • Do you own an ATV or UTV? Join our Forum!

    Join QUADCRAZY ATV Forum today for FREE! We keep these forums clean and user friendly. All first posters will have to wait to have their content reviewed and approved. Once your first post is approved, you will no longer need to got through an approval process. To gain immediate approval and a NO ADS experience, consider subsribing to our Premium Membership.

2001 400ex smoking like a freight train


Recommended Posts

Need some help i have a 2001 400ex that smokes on start up and smokes even more when you give it throttle. I just noticed that it leaks oil at the header and motor connect. I just got it from a guy that said he rebuilt the top half and he told me that the valves needed to be adjusted. But what will make it leak? Thanks in advance

Link to comment
Share on other sites

  • 4 weeks later...
Dream Car Giveaway

What will make it leak? Well unfortunately, possibly a poorly done rebuilt upper half! Oil is getting into the combustion chambers which causes the smoke. Could be the head gasket was not installed properly, or the head deck had some debris between the gasket and the head or block. Also could be the piston rings were not aligned properly allowing oil to get by. Also check for the presence of, and the proper installation of the valve seals. Oil can get by those too and drain into the combustion chambers.

Probably not what you wanted to hear, but smoke is caused from oil in the combustion chamber. These are three ways it could get there.

Also, this is probably a dumb question, but I assume you are not putting oil in the gas like you would for a 2 stroke engine.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...