if you are refering to my Saito 100 POS, I have a tach, I followed instructions, I've checked everything, had experienced people help me with it, you can't compare new Saitos with the old Saitos and I have found other people with the same exact problem that I had. Horizon, even though I have spent tons of money and love those guys there are Horizon, say it is due to vibration due to rusting internally. I was told to always run the engine out of fuel, then pump after run oil into the vent in the rear every time after flying, which I did and it happened again. The last time, they said they wouldn't fix it if it happened again and it has happened again, so the 3 year warranty is not worth the paper it is printed on. I have always taken care of the engine, I might have gotten a lemon, but never the less, Saito and Horizon are not honoring the warranty and as I said, I've since bought O.S. engines and never had a problem...much better quality engine. Super Tigre use to be good engines in the past...but now, they are not, they use to be well made, now they are mass produced in China...I think Saito is doing the same and not backing a $300 engine is just not right any way you look at it.