my brother has a sp 600, It will sit and idle but once you start to accelerate it bogs out,no power and you can smell raw fuel? We checked the easy stuff like plugs a stuff, The spark on the one wire looked a little weaker than the other but that is all we can find, any ideas?

 

The boot, check the boot between the carb and motor. Could be cracked.

 

did u try diffrent plugs? sure sounds like bad plug or wire. with gas smell anyway.

 

was the plugs wet from the raw gas? was one plug worse then the other? if so then maybe thats the weak one.