48 pilot jet is too big.

John

 

How much ethanol is in ur gas?

Are you sure?

 

Change ur needle AND emulsion tube?

 

always ethanol free.

 

ok, the bafle you are thinking about is a good idea,,,,the NGK plug is ok too, but you need to open the gap, stock spec is .38-.42,,,i like to run 40-42. 145 slow jet 160 mian and 2.5 turn out on the mixture screw would be my start point.
m

 

those cones are hit and miss with miss being most of the time. there is a sweet spot and on either side is a downward spiral. the theory is the cone necks down which causes an acceleration of the gases and just past the opening causes a low pressure area which travels down stream. when flow characteristic matches with the pipe, great, but only a sweet spot so if you ride outside of it, it actually hurts. if you are running drags on the street you need to tune for the rpm range you use.
on the above pipes i could get good low and mid then bog out or run like a scalded dog top end and have mid range issues, mpg played along also. that machine had 2" but they plain wore out but it had both top and bottom but there was a zone that balked around the 3.2>3.8k. when ramping up she would pull, lull and pull again. you will never get that dip out, only move it around.
60" and up in total length for the 1.750 is common.