juanes1969

Hello, I don´t know if this has been asked before, couldn´t find any answers in the other threads.
The engine is a 3W 106, it has about 15 to 18 gallons through it, mejzlik 27x10 at 6450 rpms. Super unleaded 40:1 with red line racing oil.
The engine was checked to see if anything was bent and came back ok. but it vibrates on idle a lot and keeps doing it up to about 2500 rpms. then it smoothes out.
The plane is an RC-pilot 35% YAK and I reinforced the engine box with 1/4 plywood triangles that go from the cowl base to the fire wall.
The transition from low to high is great, idle is 1500 rpms and top end power is great too, I was wondering if the low end needle has anything to do with vibrating at low rpms??
Even though the transition might be good, is there any other test with the needles to see if this vibration goes away or at least makes it less?
Thanks
John

STUKA BARRY

Balance and or try another propeller and see if you get the same results. What about your spinner?

Tired Old Man

My Feedback: (1)

Low end needle has a lot to do with vibration. It controls low end mixture and too rich makes for a shaker. Timing could be off a little, plugs could be dirty and need changed. Swap ends with the prop on the hub. One blade could be a little heavier and be used to offset some of the issue.

juanes1969

thanks guys, the prop is balanced, no spinner.
I'll try out leaning the low end and the the spark plugs. I don't know how to calibrate the timming, can you give me more info on how to do it?

John

Tired Old Man

My Feedback: (1)

Do the first two first. We do the "hard" part later.