So I've had this idea since I got the bike to do a sort of "exhaust dump", right as it comes out of the fairing area (forgive my nooobness talk) just lop it off right there, throw some sort of muffler design pipe (saw something with a J that i liked that just opened wide and was stubby) and call it a day, my only question is with my 2000 F4 being Carburated would I need a rejet?

 

Yep. Four stroke exhaust is more forgiving than a 2 stoke but changing the back pressure and the velocity that the exhaust exits will definately cause some issues. I'm no carb expert but I do know it will take some experimenting.

 

deff need to rejet, i did some exhaust work to my 1980 gs450L and it was running lean, think i went up one jet size and it worked fine. best bet would be to do yer exhaust work and run a O2 sensor to see what its running at or do some plug chops...


basicly run the bike at a steady RPM, say 5,000RPM and hit the kill switch and pull the clutch in, coast off to the side of the road in a safe spot and pull the plugs, see what they look like and rejet if needed, repeat this process at different RPM's. this will take alot more time then using an O2 sensor on these bikes but it does work if done right. i have yet to look at these carbs but you may even need to raise the needle a lil to adjust for the changes

 

https://cbrforum.com/forum/cbr-600f3-17/project-f-gauge-87833/

 

exactly but to get true readings you would have to use one for each pipe otherwise you could have one real lean and one real rich and wouldnt know.

atleast this is how i would think it works, i never used an O2 on my bikes, seen a member over on "The GSResource" do it, it might have even been that same thread linked to that forum.

 

provided your carbs are clean and synced and all plugs are either new or have same miles on them each cylinder should run at or near the same a/f ratio...if not then there's something wrong...thus you really don't have to put an a/f gauge for each header primary...just the intermediate