Thanks Xman,

I don't know how I missed that. When I checked and both sides had chamfered edges, only 2 punch marks at one side. May be it's not so prominent. If so, I guess the chamfered end faces the counter mass and the not so chamfered side faces the back plate. After the second damage, I didn't notice any wear on the counter mass, only on the crank case. Meanwhile I spoke to Singapore hobby supplies about the problem I have and they suggested that I bring it over in my next trip so that it could be sent to YS. What was interesting in my coversation with Mr.Johnny (of Singapore Hobby Supplies) is that the ASian F3A pilots use nothing less than 20%oil in the 170CDi. Also there is a preferance for 20 size prop to keep the revs below 7000. This is quite the contrast to all that I have read on RCU. Most of the pilots on RCU claim they fly 5-12% oil on the 170cdi.

Ofcourse when I attended Singapore NAts last year most pilots where on 170CDI (or electric) and where very happy with it. I myself am a big fan of the YS and have a few YS110s. In fact I might buy another 170cdi to get back to flying while my current engine is sorted out. I just want to make sure that I don't have a repeat of the same issue.

XMAN, what sort of fuel mix do u reccommend?