by Hadley Robinson
updated January 26, 2022
High performance two stroke engines scavenge the exhaust stream in order to increase power output. If smoke producing fluids are injected into the exhaust stream before the muffler i.e. right at the cylinder they will be drawn back into the cylinder and burned along with the ordinary fuel-air mixture. This may cause the engine to overheat. The smoke fluid may also interfere with proper engine oil lubrication. That is, if you believe that mixing the smoke fluid with the fuel mixture is OK to run through the engine, there may not be a problem. Consider, however, that adding additional oil may cause overheating.
If you install a smoke system, the fluids should be injected AFTER the tuned scavenging chamber, not before. A properly installed smoke system in the Top 80, for example, requires the injector to be placed just before the muffler rather than adjacent to the cylinder (the scavenging system).