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
rmx250rider

yzf jetting issues

4 posts in this topic

it is a 98 yz 400, and I bought it a couple weeks ago the main is a 175... it has a fmf powercore 4 and ready airfilter with backfire screen takin out... 175 is stock and tried a 180 and it bogged bad down low but was awsome up top so I went back to stock... problem now is that it is getting hotter by the day and its getting harder to start.

it always started 1st or 2nd kick... and now it takes more then 10 or more to start, but once it warms up it starts up fine and dont have an issue

should I go down on the main or try something else?

Share this post


Link to post
Share on other sites
it is a 98 yz 400, and I bought it a couple weeks ago the main is a 175... it has a fmf powercore 4 and ready airfilter with backfire screen takin out... 175 is stock and tried a 180 and it bogged bad down low but was awsome up top so I went back to stock... problem now is that it is getting hotter by the day and its getting harder to start.

it always started 1st or 2nd kick... and now it takes more then 10 or more to start, but once it warms up it starts up fine and dont have an issue

should I go down on the main or try something else?

A main jet only effects the engine performance from about half throttle through to wide open throttle. It had no bearing on your low end

performance.

Always adjust your main jet for best top end performance at wide open throttle.

Your pilot circuit comes into play when starting, at idle and small throttle opening, from closed to about quarter throttle.

Check your pilot jet and fuel screw settings and report back. You may have too richer setting on your pilot circuit for the warm weather.

Share this post


Link to post
Share on other sites
You're correct otherwise, but you have that reversed. Warmer weather requires that you adjust leaner to compensate.

Trim the idle adjustment correctly:

http://www.thumperfaq.com/jetting.htm#PJ

Thats what i was saying, meaning the pilot circuit is too rich... I think my wording is a bit confusing. :worthy:

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