Hey guys just finished building my phoenix Yak 54 and the thing was REALLY tail heavy so I had to add quite a bit of weight to the front. Anyway after I added everything and checked the CG again it felt really heavy, when I weighed it I realised it weighed 8.8lbs. No too clued up on what the weight should be but it is flying with a .61 GMS and pitts muffler. I am worried that it is going to be really sluggish, does anyone have any idea how a .61 with a claimed 2HP would pull 8.8lbs?

It will take off for sure, the question is what type of flight do you expect ?? straith and level or basic aerobatics such as: loops and slow rolls !!
for that weight a 90 2-s will take you to limited verticals but enough for stall turns, imelmans at take off and good knife edge, as well as, all "traditionals" piruets.
If you wish for more check your 4 strokes options YS 90 or 110; OS 120 etc.

It won't be a rocket ship for sure. Long ago before I gave up on 2 - stroke engines I had a Goldberg Chipmunk @ 8.5 lbs. - OS .61SF. It pulled it along pretty good. I am now flying a VenusII @ 8.5 lbs. - OS 120 FS and it is just about right.

It will fly and do some aerobatics. If it is all you can swing go ahead and be happy. If you desire and can afford more go for it.

Put a 13x4 APC on and go for it, 8.8# is a little heavy but it will fly, the 13x4 will give you max pulling power.

Thanks for all the reply's guys, I will see how it goes with the .61 (hopefully tomorrow). If it is really bad I might treat myself to a Great Planes Little Toni, put my .61 on that and get a bigger engine for my yak.

I fly a seagull Decathlon with a GMS .61 in it. Once the engine was broken in and decided it wanted to run it flew great. I have a set of GP floats that I put on it from time to time and I know that it bumps the weight up to around 10lbs or so. It flys well and will do rolls loops and stall turns fine. I think that at 8 lbs you will be fine but don't expect 3D perfomance.

So nearly a 9lb plane on a .61?. I would not even waste the time and effort to install the engine.

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In the Seventies and early Eighties, pattern ships weighed this much with a piped .61 engine. We did just fine. Of course, those were the days of jet like maneuvers. We weren't trying to emulate a helicopter in those days. <G>

Well said, Artisan, it seems that helis with wings is the in thing now, I do remember the old pattern days.