Here are a few pointers you may want to check.
Are your flywheels heavy enough to keep the engine rolling?
There can be no friction anywhere.
The cylinder and piston fit must be perfect.
The cylinder is honed and lapped.
The piston fit should be like this:
without any oil, the piston should fall through the cylinder by itself.
If you put your thumb over the end of the cylinder, the piston will stay in the cylinder by the vacuum.
The spring valve can be tricky. Only 2 or 3 thous. thick.
It's position is critical so that it covers the inlet hole when closed, but does not rub too much.
The heat of the flame will distort the spring steel and it will need replaced occasionally to keep sealing properly.
The flame position is critical too. Too far away, you don't get enough heat.
They work great once the bugs are worked out.
good Luck
Doug
