Originally Posted by
bjr_93tz
Thanks for the support guys.
With the F1 looking like a snooze-fest, I headed out to the field, the weather station at the field said ~28 deg C.
As I was sharing the field for a change (Sunday afternoon) I was being polite and limiting the flights to about 15 minutes. The first two flights were OK, no misfiring but the engine felt very flat especially off the bottom end and I was having to throttle up to 3/4 throttle just to hold speed on 45 deg uplines.
I leaned the high speed two clicks for the third flight and pushing over the top of the old Half-clover it didn't feel right and the power starting dropping off pretty quick over the next couple of passes so I landed, took the belly pan off and richened it up three clicks. Took of again and flew for a few more minutes with the belly pan off but the power was just flat but at least it wasn't misfiring.
When I landed I flipped the plane over to check the valve clearance, and noticed when turning it over TDC that the "bounce" wasn't there. The tappets had clearance but there was very little compression. The piston, ring and liner were replaced a while back to try and fix the problem with no success and I replaced that ring only 4 litres of fuel ago in case I'd cooked it at some point so it should be bedding in fine by now? When cold there's a real kick turning it over so the lack of compression at running temperature was a surprise. The new head assembly should be sealing, so it's like the new ring has lost it's tension or maybe the cylinder is going out-of-round when hot?
Sorry about the long-winded post, but I ran it without the bellypan but I still haven't gone the glow plug route yet. I'd be disappointed if the pump had worn out as it's done very little work. I'm very reluctant to buy another YS but I don't want to convert this to electric as (a) It's already heavy and (b) I'm not set up for 10S flying so there's a significant investment I need to make for the resultant 8 minute flights.
Anyway, I can't lose anymore sleep over this as the MotoGP is on at 4am and I need my beauty sleep, good thing I've got Monday off work....
Yes Brett, the opening round of F1 wasn't looking to be to exciting, Moto GP should be a bit more exhilarating.
With the Xareltoo engine, (185cdi), currently residing at the Galloways in New Zealand ready for the Trans Tasman next week, I removed the Valiant engine and put in the Xareltoo so I could get some practise this week. So with the F1 set to be a bit boring I headed off to the field for a quick flight as well.
Anyway, this is leading back to your comment about the lack of compression. The Valiant engine has less compression when turned over by hand than the Xareltoo engine has. I have noticed this in the past, but when it comes to flying, I can't tell any difference in performance between the two. Probably not much help to your situation, but interesting.
As for going electric, i have a large investment with IC set ups and it would cost me thousands to convert to electric, so as I have a good record with YS, I'll stick with them.
PS. There's nothing like being one of two YS planes in a field of 43 entries
.