Jump to content
Sign in to follow this  

Honda What's wrong with my 400EX

Recommended Posts

My 400EX has problems idling. I'm wondering if any of you can point me in the right direction before I start heading in the wrong direction. The bike is stock except for the pipe. It has a DMC exhaust and I changed the jets to what DMC recommended for that pipe. It's always done this since I've owned the bike. It's more annoying than anything. If you ride the bike for a while, the problem subsides significantly to where the bike will idle. But it never goes away completely. It acts like this when the bike is not warmed up. My thought is it needs a valve adjustment. But was hoping I could get some guidance from some of you. I posted a video of the problem on youtube here:

http://www.youtube.com/watch?v=0pPxBq-3LbU

I appreciate any help or suggestions. Thanks.

Edited by sumnone

Share this post


Link to post
Share on other sites

...sounds like the pilot jet is a little lean. Try going up two sizes and see what that does.

Share this post


Link to post
Share on other sites

Ok, that sounds easy enough. Since I had already replaced that, I hadn't given it any thought.

Share this post


Link to post
Share on other sites

I would say you have a gummed up pilot jet. Very common problem given the poor quality of modern fuel. Did the engine ever sit unused for a period of time? This will make you very lean at idle, and a little lean overall. Don't bother cleaning it. Jets are cheap, so just replace it. But.....most likely your whole carb could use a cleaning.

Never hurts to do a valve adjustment! Definitely do that no matter what, if you haven't done one recently.

Edited by reconranger

Share this post


Link to post
Share on other sites
...sounds like the pilot jet is a little lean. Try going up two sizes and see what that does.

OK, I didn't at first notice the statement "it has always done this since I owned the bike"....so yes you probably need to fatten up the pilot jet! The lesson here is, that it is rarely possible to jet properly by just dumping in the jets that an exhaust manufacturer recommends, without having an experienced jetter ride it and evaluate the results.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×