can someone tell me the major size differences between a 2 hp and a 2 1/2 United type A engine please? The Flywheels, bore, stroke, length of engine overall. I picked up a 2 hp this week but was wanting to get a 2 1/2 hp. If the differences are not that much I might just keep the 2 hp. Thank you Tim Christoff Basehor, KS. Tim Christoff