hi, i run a 94 cbr1000fr its fitted with a k&n filter and a lazer exhaust with a k2 silencer fitted, she runs great but was wondering if its worth fitting a dynojet kit as well and what stage would you go for ?
john

 

I have an 87 with a Vance and Hines SS2R exhaust. I put in a jet kit (had a mechanic do it, actually) because it was really weak in the midrange. Much better now. It still needs tweaking as it hesitates a tiny bit under hard accelaration at about 5k rpm.

I'm not sure about the stage, though.

 

From what I have heard, Dyno jet kits causes wear on the emulasion tubes (the brass tubes that the needles goes in) in the carbs, caused by the needle material being harder than stock. This causes a too rich mixture with time. What a Dyno Jet kit does, you can do with standard jets for half the money. Dyno Jet kits also consists of softer springs for the vacuum control of the throttle piston. According to what I have heard, this isn't necessary on most bikes, and almost excessive on many bikes. my 2 cents...

 

cheers chaps, this is the info im looking for, most places stock them over here but few can tell you the benefits or drawbacks,
more headwork i think
j

 

These bikes are overjetted as standard, and unless you're running competition headers and not just slipons, I'd leave them as they are. Mikekop is right.
I run a K&N and non-standard headers and pipes, and a stage 1 jet kit, and she's too rich.

 

My '94 has a V&H full system and a K&N. I fitted a stage 1 Dyno Jet kit and had a lot of trouble getting it to run right (I got pretty good at getting the carbies on and off though!). In the end I found that I had to run on the leanest setting andeven then there was a problem when I cracked the throttle wide open. I found out after much trial and error that the springs were too soft and so I put the old springs back in.
Now it goes hard with better mid range and top end (by feel nottested). If yours is running fine and the plugs don't show it's lean I wouldn't spend the cash. If it is a bit lean you could fiddle with different jets and maybe spacers under the needles for a lot less $$.

Dave.