HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
dustindaulton

98 yz400f oil leak??

8 posts in this topic

Hello, I'm new to the thread and relatively new to dirt bikes. I had one in jr. high school but i am now 27 so yeah, its been a while. I just picked up a 98 yz 400f for 1,000 bucks. it runs great and starts easy but after riding it leaks oil out of the tube that comes down from the top of the engine on the left side. I've cruised the forums and found out that it is common to leak a few drops of oil here, but i think mine is leaking excessively. after every ride, be it ten minutes or two hours, i end up with about a 4 to 6 inch puddle of oil on the floor. it does not happen quick, but leaks out little by little after it is parked. is this something i need to worry about?

Share this post


Link to post
Share on other sites

That is your crankcase breather. First off, I would check oil level.

Share this post


Link to post
Share on other sites

Agree with dgcars, before you do anything else check your oil level.

To do this you need to run the engine (assuming it is cold) for about 1.5-2 mins at idle. Remove the dip stick (which is at the top of the frame behind the steering head) and check the oil level (screw out the dipstick and check the level without screwing the dipstick in).

Share this post


Link to post
Share on other sites

Thanks for the replies. sorry it took so long to get back to you. I let it idle for about two minutes and checked the oil. It was about half way between full and empty so I don't think it was over-filled. There is a Yamaha dealer just down the road from my house. Is this something I should be taking it to them for, or is it no big deal?

Share this post


Link to post
Share on other sites

Are you sure the excess oil is leaking from the breather hose ? Maybe you have a leak from somewhere else as well.

Share this post


Link to post
Share on other sites

I've looked the whole engine over and it is clean and dry everywhere. If I run my finger around the tube outlet it comes back with a decent amount of oil on it. Also the puddle is directly underneath the hose. I suppose it is possible that it is coming from somewhere else, but if it is I can't tell where. Any common places for it to leak?

Share this post


Link to post
Share on other sites

No it's not likely the oil is coming from any where else if the rest of the motor is clean & dry. Most likely there is a little bit of 'blow back' from piston/ring wear. So either live with it if the motor is running good, or investigate further. Your choice.

Edited by dgcars

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  
Followers 0