Jump to content
Sign in to follow this  

Science Experiment

Recommended Posts

Ok here I go. 98 XR 400R its getting a Wiesco 88mm 11:1 compression  big bore kit, new valves, guides some mild porting work. It has a two brothers pipe already on it. Gonna use the stock cam Has anyone out there done these mods and have jetting suggestions or parts suggestions. I'll take them all into consideration. I'd like to use slide carb but after the rest the wallet will be in sad shape for a minute. Thanks Doug

Share this post


Link to post
Share on other sites

If the carb was jetted properly before the big bore and mods, I suggest starting with that same jetting after the rebuild. It's not going to change much at all. The increased displacement creates higher negative intake pressure and vacuum signal on the same jetting.

 

At least, that's been my experience.

Edited by Trailryder42

Share this post


Link to post
Share on other sites

If the carb was jetted properly before the big bore and mods, I suggest starting with that same jetting after the rebuild. It's not going to change much at all. The increased displacement creates higher negative intake pressure and vacuum signal on the same jetting.

 

At least, that's been my experience.

 

I agree.  More displacement and/or more efficiency equates to more air being moved and more signal across the carb.  Start with what you had (if it was right) and go from there.

 

I use Mikuni's Roll-Off method to get my mains dialed in.

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  

×