I own a 89 1000fJ, I recently added duel aftermarket slip on exhaust and now the bike is running lean. I am told jetting is the answer. What I am looking for is stock jet sizes? if anyone has run into this issue before? if anyone has rejetted up sizes? and what's working for people as far as rejetting in general?

 

Welcome the the forum.

Here is a LINK for jetting.
Yes you will need to open them up some. They are lean from the factory due to emissions anyway. If you haven't done so yet, check out the HOW TO section for the stick coil mod. The stick coils and fr-jetting will have she singing nicely.

Don't forget to check back in to let us know how you made out.

 

This may be a little back-woodsy but i drilled out my low-speed jets. The smaller of the 2 removable fixed jets (pilot jets?) in the float bowl feed a series of ports that are progressively exposed by the butterfly valves, just off idle, before the valves open enough to use the mid range jets, to the best of my knowledge. I took a hobbyist drill bit set of my father-in-law's, and found the bit that fit perfectly in the jets, then went the next size up and carefully HAND drilled them out. He was a kawasaki mechanic for many years and i wouldn't be brave enough to try this on my own. It only takes a few turns by hand. since you are running stock headers and just have slip-ons, maybe this would be enough to overcome your problem? It made a big difference for me on low end acceleration. The EPA forces bike makers to under-jet the bikes for emissions standards. They dont run right stock. I am also running dual slip on Yoshis now, but they are baffled and not far from stock. Everything else i have is stock.

 

Thanks everyone for your input. I orderd a mild set of jets and shims. Will see how this helps. Also found my tank is a little weathered, so I will be doing an acid treatment on it and hopefully clean up the fuel a little bit

 

Nice link TBT, just got quoted $55 for a full jet and shim kit (125 mains, 38 pilots and 2 x shims) that's £38 in British money!!! I sent an email asking for shipping costs and they said "usually free"!!!!!

Thanks for that.