Ok i had a stock 92 cbr600 f2
exhaust was stock
Now has a muzzy can on the back with stock everything except the pipe going into the can.
the bike spits and sputters alot now that its been changed so im asking
do i rejet carbs?
or what should i get done.
Thanks for any info and there are shops around but theyre closed and im working all day tomorrow so no chance to call them.
/e - The bike spits and sputters when coming down in rpms
cruises around 7-8k nicely coming from 11 down it spits and sputters till about 6
unless crusing then its fine.
idles fine(little harder to cold start)

 

Adding any free flowing exhaust or air filters will cause the engine to run "lean" because you are allowing more air to flow through the system. (It's more complicated than this, but this is the simplest way to describe what's happening.

So, there is now an excess of air in your air/fuel mixture and you need to add more fuel.

You're on the button with the jetting change, you will need a "jet kit" to get you in the ballpark and then you'll need to spend some time tuning it.

You could end up with a flat spot, or running too rich altogether, so you will have to play with different jets and different settings.

Each jet, the pilot screw, and the needle controls fuel mixture at specific throttle openings and engine speeds.

Do some research and be patient, it's not easy to get it running perfect. (A couple hours on a dyno with a professional will give you WAY better results than you can accomplish alone)

 

so if i was to purchase a set of carbs that were stage 3 jetted that were sync'd and whatnot and just rebuilt and all that from a shop wouldnt be a good idea?

edit
i couldnt send the carbs and $$ to get them rejetted and tuned by someone like you sandman or does it have to be done on my exact bike?

 

I wouldn't recommend it... "Stage 3" really has no meaning other than the manufacturer of that carb kit specifies that the kit is for more mods than just a slip on.

That and the carbs may be "sync'd" but they are not sync'd to your bike. Every bike draws different volumes and vacuum, no two bikes are equal, so a set of carbs must be jetted and sync'd to the bike they are to be used on.

You are better off using your carbs, and putting your bike on a dyno (not to find out how much horsepower you have, to find out exactly how lean you are) and install the proper jets / tune your pilot screw and needle clips

 

hmm i guess its time to invest more money on labor at a shop lol
unless someone knows a larger carb off a f3 or something i can put on it and use it until i learn syncing and everything else

 

I need to rejett myself. There isn't a lot of documentation on doing it, and dyno time isnt cheap.

I get exactly what you get: Sputtering when engine braking from ~10k down, stopping around 6k. That's where your main jets are rocking, so they could stand to go up in size. Then there's that whole adusting clips thing and... well **** I have no clue what I am getting myself into!

I'm just going to have to hope for the best!

 

Main jets as my grandfather explained is take the bowl off remove the jets and put new ones in then replace bowl?
im not 100% sure
im going to look online for a COMPLETE step by step carb rebuild pdf for the cbr 600f2/jet guide something.

 

We have a carb rebuild sticky in this forum, with pictures!

Changing the jets is easy, figuring out which ones you need is where the black magic exists.

You can try a Factory Pro or DynoJet jet kit, you can get "close enough" with one of those on your own just following their recommendations based on your modifications/elevation

 

Just to give everybody an idea of how important correct jetting is, and to reiterate that there is no "kit" that will give you perfect jetting straight out of the box...

On my TZ 250 GP superbike I change my jetting on average 3 times a day on race days... Morning/afternoon/evening due to temperature and humidity changes. If I'm not correctly jetted I can lose up to 10 HP, and worse if I am too lean my engine will overheat seize!

But, that is the nature of a 2-stroke GP bike... Tight tolerances and a very picky engine

 

alrighty and where do i look for the guide with pictures?
i dont think i need to go all out in size of jets because its not that bad off one flat spot in 3rd gear at a certain 5500-6500 rpms
then decelerating from 10-6k it pops a little