150/52.5#  main/pilot should do ya'... ...

a.   let's wait and see...
b.   that's not something you want to do... nothing good will come of it.

Try those jets, and see how you like them...

I had very good luck with a #150 main and a #50 pilot......a 52.5 pilot is also a good choice to begin.  Going to a #55 pilot is most likely going to be too big.  The proper pilot jet size will result in the idle fuel mixture screw being about 1.5 - 2 turns out from lightly seated....you adjust this with the engine running and keep turning it in/out until you find the engine runs the smoothest.  If you can turn the screw all the way in and the engine still runs....the jet is too big - if you can turn the screw out 3 turns and the engine is still running smoothly...the jet is too small.  The idle speed should be pretty low when making this setting, as a fast idle speed will begin to open the slide and make the idle mixture screw adjustment impossible.  This is the only time that a low idle speed is permissible....the normal idle speed needs to be about 1,100 rpm so that the oil pressure is adequate to keep the cam and rockers lubricated.

With the changes you may need to consider the white spacer mod on the needle as well.  Remove the white spacer and install 3 washers on top of the clip...the washers are #4 machine screw size.  If you have a low speed surge/stumble just off idle when accelerating slowly....remove one spacer from the needle and try 2.


Dave