what size main jet?

72 is as good as it gets. the air filter will make little difference on a 50 unless you add a big bore kit. If anything the K+N will be worse in damp or rain; as the standard one is protected from water. I run a standard air filter, size 72 jet, gianelli hand made race pipe with size 6 variator rollers and it clears 50 mph+ you can't get much more without a big bore kit or losing too much bottom end power.

Jeff Cooper ( lord Petersham )
June 2009

hi steo.my speedfight 2. has all been deristricted and a giannelli race exhaust fitted.now want to fit K/N type filter. to give it a bit of excelleration pulling away . any help.

rayb
June 2009

a 72 main jet is big enough for a standard ped with just a k&n filter, you would up-jet if you had fitted a race exhaust. to richen the fuel mix & get a bit more power then raise the needle by inserting the circlip into the middle groove, then turn the pilot air screw in half a turn. bring the ped for a good drive & then take out the spark plug & check for a nice gold brown colour. your set-up is correct if you are getting this, let me know how you get on.

steo
June 2009