Sorry guys. I got distracted and hit the post button before finishing.
These are two extreme examples in my collection.
The bolt is huge at seven inches long by one and one half inch in diameter!
And the engine is my tiny "Tiny Valveless" that is based on plans sold over
the internet. I don't remember the sellers name.
Seeing the two side by side makes an interesting photo that raises the question of whether the motor is tiny or the bolt huge.
The answer is yes to both parts of the question. ;D
-MB