i'm working on a couple karts right now, just remembered i have an old five horse briggs I/C flathead a couple days ago.gonna use it on my margay for the time being. i've done some research. the raptor is a 5 horse briggs I/C with some go fast stuff from the factory. raptor 1 was just a decent piston and rod. raptor 2 was piston, rod and maybe some head /valve work. raptor 3 is #2 plus dual ball bearing crank. you can find stuff on ebait BUT be wary of people saying its raptor stuff when it isn't. raptor parts are in a yellow and black box and say briggs motorsport on them. rods will have a integral dipper and say r1, r2 or r3 on them and the cap. most kart shops still have some raptor stuff too. just google it. wiesco pistons are out there too. from what ive found a stock raptor rod is good to 6-7000 rpm depending who you ask. i'l be getting a raptor rod and piston hopefully. arc billet rods are about 50- 70 bucks. since your motor has that block girdle on it, i would say its got some good stuff in it and very well could be an alcohol motor. what carb is on it? got some motor pics?