JackinMichigan
Well Known Member
I currently have 21 hours in my RV-10, brand new engine and prop, and I've been following the break-in advice by running it at 75% power as much as possible at near full rich. Lately when doing my magneto checks at 1800RPM I'm noticing that the RPM drop has ratcheted up to 180RPM per magneto (it started out at around 130RPM).
I had a similar problem on one magneto when the engine was brand-brand new and I was able to track it down to a timing issue. I haven't re-checked the timing yet, but the RPM drop is near identical for both magnetos.
Also, when doing the magneto check I can feel a slight shudder when I switch off the right one, which smooths out again right away. I feel no such shudder with the other one.
I haven't seen a major temperature drop in one of the cylinders to indicate a misfire, but I also don't generally run it long enough on one magneto to let the temps stablize. Once both magnetos are on the engine runs smoothly.
I'm a little concerned I'm fouling my plugs. I had an instructor once show me a little trick where he would lean out the mixture while running on one magneto to elevate the temperature enough to burn off any plug fouling. I tried that, and I saw the CHT on one cylinder rocket up 50 degrees in a matter of a few seconds. I immediately shut that little exercise down.
So - is it plug fouling or something else? Is this sort of stuff normal?
I had a similar problem on one magneto when the engine was brand-brand new and I was able to track it down to a timing issue. I haven't re-checked the timing yet, but the RPM drop is near identical for both magnetos.
Also, when doing the magneto check I can feel a slight shudder when I switch off the right one, which smooths out again right away. I feel no such shudder with the other one.
I haven't seen a major temperature drop in one of the cylinders to indicate a misfire, but I also don't generally run it long enough on one magneto to let the temps stablize. Once both magnetos are on the engine runs smoothly.
I'm a little concerned I'm fouling my plugs. I had an instructor once show me a little trick where he would lean out the mixture while running on one magneto to elevate the temperature enough to burn off any plug fouling. I tried that, and I saw the CHT on one cylinder rocket up 50 degrees in a matter of a few seconds. I immediately shut that little exercise down.
So - is it plug fouling or something else? Is this sort of stuff normal?