I have a 89 cbr 600 with no fairing and a k&n filter and I am putting a full yoshamura system on the bike and I will need to rejet. Any suggestions?????

 

I bought my 87 with a full vance and hines and a k&n already on mine and I went with a factory pro stage 3 because with the stock jetting it was running quite lean. It took a bit of tuning to get the needle height right though. I also have their ignition advancer

 

find your local shop with a dino. they sould be able to tell you what size jets to put in. this will save you alot of head ache and time not playing the guessing game then pick your jets from there.

 

Dyno, not Dino(saur?)

Stage 1 or 2 from Dynojet or Factory pro should be more than enough with just a K&N and slip on, depending on altitude. Stage 2 for sure with full exhaust.

Tuning is a pain, but a street tune will pay off in spades.

See here for a good how to:
https://cbrforum.com/forum/cbr-600f-...et-kit-127567/

 

Click on this LINK. (best price around) With a full 4-1 I'd go with fully modified to step it up to adjust for the ethanol in the fuel. The lack of faring has nothing to do with how the engine runs.

They suggest, four Main jets size 112, four Pilot jets size 40 and 2 shims for each Slide Needle.

Also, the jet screws should be turned in until light touch and then turned out 2and1/2 turns.

 

I am going with full yoshimira exhaust headers back. When I go the bike from my friend one of the air intakes was plugged of so it would run correct. I thought it may have been because of less air restriction without the fairing. I unplugged it and it ran horrible.

 

Taking the fairing off can cause issues a guy on custom fighters did a write up how to fix it. His name is Mustpha dump here's his fix.
"The main cause of issues when the fairings are removed is the float chambers seeing a slightly lower pressure than the airbox sees when moving at speeds above 45mph or so.
The ZX series of Kawasaki sportsbikes suffer from this problem very acutely.
What you really need to do rather than restricting the amount of air entering the airbox, is to enable the float chamers to see the same pressure reference as the airbox.
The easiest way to accomplish this is to find the two Tee pieces between carbs 1&2 and carbs 3&4 which are the float chamber vents, on some banks of carbs on the Hondas it is one large Tee piece between the 2&3 carbs as all 4 carbs are linked across the top.
Once you have determined the float chamber vents, attatch a short length of rubber hose to the Tee piece, and then run it into the airbox through a hole drilled in the underside just large enough to pass the hose through tightly.
Face the open end of the hose towards the front of the bike under the airfilter, if needs be slash cut the hose at 45 degrees and face the cut upwards and forwards.
By doing this the float chamber vent will be fed by the air entering the airbox which then ensures that the pressure in the float chambers is equalised with the airbox pressure, once this is achieved the air passing through the venturi will suffer a slight pressure drop, as this happens the air pressure in the float chamber becomes slightly higher than that in the venturi directly above the needle jet/jet needle, and this higher pressure in the bowl then forces the fuel up the needle jet/emulsion tube and introduces it to the airflow through the venturi where it is then atomised and carried into the cylinder.
I've had to sort out quite a few "Ramair" issues on sportsbikes that have had the fairings removed over the years, in the past the issues have been difficult to detect as they don't generally manifest when I have the bikes on my dyno, although I now have a dedicated ducted fan which I use to blow air into the airbox intakes in an effort to replicate the problem as it occurs on the road rather than me going out and testing the bike on the road myself which isn't always a practicable option when it is pissing down with rain, or during the summer when the local roads are crowded with tourists heading towards the coast."

I did it to mine and fixed my issues
Heres the link http://www.customfighters.com/forums...=mustapha+dump

 

^ That's interesting. I wouldn't think jetting is effected but equalization of air pressure is important. Good thing you brought that up.

 

I got a 6sigma kit and jetted it 112 on 1 and 4 and 115 on 2 and 3. I was cutting out at highway speed. So I plugged the one intake hole like it was before and it runs better, but I would like to have both air ways open. I am going to put the 115 on the outside cylinders and put 117 on the inside but I doubt that will be enough. Other than that all is good way more responsive and I didn't even trim the needle spring yet, but I did drill the slide.