Jetting Issues? some inout please!

My son has a 04 250f . We bought the bike from a local "A" rider . The bike had all the goodies and was fast as heck. The motor was done by a east coast guru always refered to as Coby.

End of last season the bike lost compression. I took it down and found the psiton to be cracked. Comparing the dome on the cracked piston to a stock one I had laying around, the dome was considerably higher, so i assumed this was a high compression piston. I was told when purchasing the bike to only run race gas. In reassmbly, i opted for a weisco factory replacenemnt, efectivley lower the compression, FOR 2 REASONS. My son isnt a "A" rider and we ride alot ,i wanted to be able to use pump gas. The head on this bike is a work of art, the porting looks GREAT. I have no ideas what cams are in it.

But to the heart of things.

Once reassembled , the biken wouldnt run at anything below 3/4 throttle. It popped and spit ect ect . I checked the jetting. It had 172 main 40 pilot. I had a whole nother bike, so i put in the 178m 45p that came in that . the bike ran better but still spit and popped down low and hiccuped when accelerated. i can run the fuel screw WAY out and it seems to run fine,to the

point where tI have to wedge the vent hose against it to keep it in the carb. I have checked the carb and cleaned the carb numerous times checkd the float level numerous times.

I am assuming i need to fattin the main and pilot up a bit? I am assuming that out on the fuel screw is richer?

I have checked for air leak between carb and head ,several ttimes.

Is is normal to have to fatten this up so much from only lowering compression?? I have replaced chain and guides , and checked and rechecked that stufff. I am just wondering if lowering the compression would have that much afect on the jetting? Any input would be greatly appreciated! TIA Rick

I found some spec's on the Pro circuit site that worked great for me. A slightly modded bike at sea level in Northern Jersey.

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