Joe the 2HP engine would power a small motorbike....what I need are drawings- I am a machinist and have use of a workshop so I can make the Stirling myself if I have drawings- for a Stirling just big enough to charge the batts on an electric bike- 200 watts, or quarter horse, would be enough to run a dynamo to put some power into the batteries as the bike travels, to extend the range of the bike. And of course when I get where I'm going and the bike is stood, the Stirling is thudding away to fully charge the battery.
There are alternative of course. One is to carry a second Lithium battery, which costs over Ã‚Â£300 and has a finite life in terms of number of charge cycles. Another would be to use a little 'weed whacker' two stroke to drive a dynamo, but they are noisy and smelly.
In the UK/EU an electric bike of 200W power counts as a bicycle in law, I think it's a 1 horse/740W power limit in the States!, and carrying a generator setup is only limited by overall weight limit which I think is 40kg.
Apart from the fun of experimenting with Stirling engines and the design of the generator setup, there are questions of costs and practicality for ultimately a long range touring electric bike which does not need to spend a night hooked up to the mains for charging because it has it's own generator.