Porting difference & low end bog?

[Glitch]

Hey, just got a new(to me) 02 yz125 :yeehaw: and the guy said he had stage 3 porting done to the engine by Reactive. Along with fmf sst pipe and shorty silencer, rad valve, and runs on race gas.
First question. Whats the difference between stage 1,2 and 3 porting? Do they shave the head on one of the stages, and what about changing port heights and widths.
Second question. With all the porting, pipe and reed valve, this bike is meant for high rpm power, not low end. But even after the bike is all warmed up and stuff, when the bikes in neutral and idling, it has a small bog when I wack it open. Is this mearly a jetting issue, or is that kind of normal with all the mods.
Also, is there something else that I can do to it because its running on race gas? Since I'm paying for the expensive stuff, I mind as well use it to its potential.
Thanks
Jim

 

[wasted]

I could very well be wrong, but to my knowledge it breaks down like this...

stage 1 is just a basic clean up of the intake and exhaust tracts, no port modifications...

stage 2 is stage 1 plus matching and cleaning up of the transfer ports...

stage 3 is 1&2 plus reforming(raising/widening) the ports, I think reshaping intake tracts falls under stage 3 too, but I'm not sure...

there is a stage 4 too... which to my knowledge involves splitting the cases, I'm not firmiliar with what is involved with stage 4, and cant remember what little I did know of it, maybe reshaping the intake tract falls under stage 4... I'm not sure...

I'm no master at it, but I've done some of my own porting, nothing too radical though, what I would call a mild stage 3...

I would try adjusting the airscrew to get rid of that off idle bog...