Review on A Similar Digital Tach Hour Meter Tachometer for Gas Engine Maintenance – Max RPM Recall Function – Suitable for 2/4 Stroke Engines, Including Chainsaws, Snowblowers, Lawnmowers, ATVs, Boats, Motorcycles & Marine Vehicles by Jaime Miranda

I used it to tune 3 chainsaws. These were a Husqvarna 142e, a Poulan Pro PP4218AVX and a 1979 Stihl 032 AV with dots and a condenser. I tuned them by ear and used them to test my settings. I shot about 3000 on low and about 13000 on high. He confirmed that my low settings were spot on (I had just over 3000 but the chain wasn't moving so the clutch wasn't engaged) and that my high settings were a little low. I used this to increase the high RPMs by tilting the H-bolt a bit on the carburetors. I set the upper limit a little higher than by ear, but still stay below the maximum speed of my saw. Your saw and your ears will tell you where they work best, but this is a useful, inexpensive tool that will tell you when you might be having trouble with a saw tilted too far. I didn't have to wrap the wire around the spark plug wire, I could just clip it to the top cap and get a good reading.