Smoke use with 2 stroke paramotors

by Had Robinson

Flying with a smoke trail is just plain COOL!

Most pilots, however, do not think about what is actually going on with a smoke attachment to their 2 stroke paramotor.  All 2 stroke paramotors have a tuned exhaust which sucks unburned fuel out of the cylinder and then stuffs it back in again, just after the intake port closes.  (For the details of how this works, go to this page on tuned exhausts.)

In a nutshell, any fluid that is introduced into the tuned part of the exhaust system will be sent back into the cylinder and burned.  Is it a good idea to introduce some cheap oil or non-lubricating fluid into the cylinder where it can displace the good, 2 stroke oil as well as be burned?

In other words, if you would add the smoke fluid into the fuel/oil mix to begin with, you will be OK EXCEPT that the addition of whatever it is may increase combustion temperatures inside the engine.

If you want to have a smoke trailer, here is what to do:

1. Only use the exact same 2 stroke oil that is mixed with the gasoline. DO NOT USE KEROSENE OR JET A!
2. A CHT must be installed in order to monitor engine temperature.
3. Make certain that the smoke injector does not leak.  Leaks in the tuned exhaust system of a 2 stroke engine may cause it to overheat.

Use of smoke will cause increased fouling of the spark plug and increased engine deposits which requires increased engine maintenance.