2011 engine Mod question

Going to install a vertex 13.9 piston and a stage 2 exhaust cam in my 2001 kx..Was wondering if I would have to go with stiffer HD valve springs?? Also would Race gas be a must?? Oh and would I have to do anything to the head for that cam to work??


Most likely with the cam and the 13.9 you would pobably need a higher octane fuel.. 94-98 should probably be ok.. With the stage 2 hotcams I've read that some may need shaving to get clearances to work.. as far as the valve springs go.. Well honestly I can't answer that question.. hot cams says no but if you have a lot of hours on the bike I would be replacing the springs..

Well I just installed a hole lot of parts on my 2010 kx250f. For that comp ratio 93 oct. should work just fine. I am running JE 14:1 HI-COMP Piston, del west valves, copper seats, copper guides, and Stage 2 hot cams. I would just replace the valve springs every 25 hours or so to just limit the chance of a valve floating. The stage 2 hotcams are a nice setup with a hi comp piston. If you have an aftermarket exhaust then the cams will really show there potential up top in the rev range due to stage 2 making power up top.

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