I can't get behind this. I spent a good long while installing and tuning a new jet kit after riding with the race exhaust and tuned stock needles for a while, and once I got it in the sweet spot, the difference was very, very noticable. Granted, we have two different engines.

 

Yes they do need a jet kit.When these bikes were the latest-greatest,the EPA would get the bike to 6th gear at the national speed limit.The bikes came in this country lean-as-a-snake at that rpm.Guess where?Right in the middle.They were kinda rich on the other ends of the rpm range to balance the lean-ness out.They need to be fattened up.

K&Ns do not work well with carbed bikes.Reason is the airboxes were designed for velocity and vacuum,not volume.Otherwise we could just remove the airbox,use pod filters and be done.K&Ns screw up the vacuum in the airbox,causing the slides to not come up in sync.This KILLS the midrange and peak power delivery.If they were better,I'd use them,believe me I would.Not to mention more trash gets into your motor using these K&Ns.The street has way more trash than the track.God only knows how much I've spent learning this.But believe what you want,and I'll believe what I know.This is not only true with F3s,but F4s and SV650s also.

Moving the cams changes how your motor makes power.Want more peak power?Move the cams.Want more mids?Move the cams.Want it to pull hard all the way to redline,like mine does? Move the cams.And you don't have to buy sprockets.Doing this on a stock motor does make a difference,believe it or not. Why do you think most of the modern bikes now come stock with cam timing set @ 104deg,or thereabouts?

Stock pipe is a choker,plain and simple.Get one that's well packed.The newer the design,the better.All you gotta have is a 2" opening.I have a mid-pipe that I had modifed with a 2 1/2" opening so I can use GSXR 1000 pipes.Yes,on the dyno,I saw an increase with that also.No,it was not louder.D&Ds and Muzzy pipes are the loudest.Ugh!!

People,I've spent many many many hours and many many many more dollars learning what makes these bikes work,and work well.I have the sprint and endurance,regional and national race wins to back it all up.I get the same compliments "Man,that thing is FAST!!"
In the WERA circles,I am the go-to guy for setup.They call me King Kenny the evil parts hoarder and F3 guru.I am sharing this with you.But I can't make you do anything,all I can do is offer.

 

Just reading about your racing credentials and that's good enough for me. I've also had trouble with anything other than stock air filters etc.

Anyway I have recently purchased a CBR600 F2 for the track which started life as a California Superbike school bike and I will be getting an f3 for the road next weekend.

I've only ridden the F2 once so far on a track, it has really low gearing to mask a pretty weak bottom end and mid - range. It has a K & N filter and full Vance & Hines race exhaust, apparently it is jetted to suit. What would you advise to beef up the mid? I'd like to raise the gearing as I don't like dancing up and down the box all the time. A mid range on par with an early stock FZR600 would be good enough and I don't mind losing a couple of bhp at the top end as this is going to be my wet bike when I get my Zx10 sorted.

I've done a few adjustments to the suspension to make it handle better than the barge it is, generally getting things to corner is what I'm good at but I have little idea when it comes to engine tuning. There is a flat spot between 5 & 6000 rpm which is also pretty annoying as that is the engine speed I'd normally aim for off the brake and starting to wind the power on mid corner putting it on the pipe as I exit. The flat spot means I sometimes have to slip the clutch.

I'll try a stock air filter if you think that might help, I've also popped in a new set of spark plugs just in case for my next outing.

 

K&N and the like mess up the vacuum created by the air boxes.You want the slides to rise and fall together.Makes the bike easier to ride.If the carbs are in sync,the engine runs more efficiently.The more air=more power theory is not true.Japanese inline fours make power through crankshaft inertia and airflow velocity,not air volume.This ain't your grandpappy's 1970 Chevy pickup.

The EMGO brand and Hi Flo brand paper air filters are made in the same plant as the oem filter,right down to the markings on the plastic.Half the price too.Those K&Ns put that flat spot in the midrange.

Holes in the airbox lid do NOT help.Don't do that.

15/45 gearing works well most anywhere.Longer tracks like VIR go to 15/43.

For spark plugs,go to an auto parts store and tell them you want plugs for a 2000 CBR 929.These are iridium plugs for $28 a set.They last longer and throttle response is better.Starts easier too.

Midrange? Nothing you can do there for an F2 really.Cams would help,best of luck finding some....

Put an F3 rear wheel on your F2.Plants the bike better in the corners.

If you've got the coin,EBC front rotor kit.Don't use EBC pads.No feel.I don't like them.If you feel like hunting,get an Ohlins shock.There's one on eBay right now.Rebuild is usually around $200.If you get one rebuilt,use an Ohlins certified tech.Penske guys do not know how to rebuild Ohlins shocks.Learned this the hard way.

A pipe with the right jetting will boost power.Comparing these bikes to new bikes is,well,reaching.Mine jumped 10hp.I've learned that these bikes like oval pipes.Search eBay for Akrapovic pipes with a 2" inlet.I scored one from a BMW for $108 on my doorstep.

Valve adjustment will be a big help too.

 

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