That is eather a very old novarossi engine or one that has a boost bottal mod done to it. See the niple just under the carby there would of been fuel line on it did it go to one in the engine backplate? or to a litle chamber like a tiny bottal?. I'm not shore with the pic you have posted what engine it is can you post ones of the back plate, liner, and the righting on the top of the engine head. Regards Jeremy.