A compression measurement should be taken when the engine is new and when its at operating temperature. This will give an starting indication measurement to go by.

Its a good idea to check the compression from time to time to see how far off from the original number it is.


Someone stated earlier that an engine showing compression loss will not idle correctly etc.
This is not a true statement, if the engine was that worn out, it would never be able to hold fuel in the line up to the carb to get started. Even if you put fuel into the carb it would not start.

From my experience a loss of compression will yield engine failure. In that the engine will start, idle and run as it always has, however once the engine reaches the upper regions of the temperature range (normal operating temperature) then engine will just all of a sudden stall.
Numerous attempts to re-start the engine fail. Thing is that if you wait a few minutes the engine roars back to life and we began the cycle again.

2 things are happening to cause this behavior. First, once the temperature gets up to where it needs to be, the sleeve expands. Normally the engine runs great, however with worn internals the parts no longer have a tight fit like before. Thus there is loss of compression and the engine stalls. Attempts to re start fail because the engine cannot hold or pull fuel because of the heat.

Secondly the engine cools, it starts fine again, the internals shrink and once again there is a tight fit in the internals.

The amount of fuel that goes through these engines is an individual basis, each engine is different and tunes a little different.
Each owner has their own preference of fuel and maint routine.
Climate, frequency of run time, and your behavior with the model all affect its lifespan.

The bottom line is like anything else, take care of it and it will take care of you.

Work smarter not harder.

Dbow