A Tiger Shark 75 is a perfect match for your cap. I had a Webra 50 in mine at first and it was tail heavy so in went the 75 and it balanced perfect and it's probably the best engine they have. Mine was ringed but my bud had one that was abc and there was only a 200 rpm dif between the two on the same prop and fuel the ringed version cranks a little more rpm's and both sip fuel like a 46 instead of a 75.