Retrofit bearers like the ones in this post?  Then you can try different engines.  The ones pictured are based on a stick of 1/2x3/16 2024 or 6061 aluminum (I can't remember which) bought from Online Metals for cheap.  You just whack off lengths, do some work in a drill press, and you're done.  I drill & tap the holes for the engine screws, but I know other people prefer to drill through-holes and bolt things on.

So, Bob and I tried to get my McCoy 35 running last night for an RST I built for my nephew.  The motor is just too tired.  once warmed up, you can get almost two full revs out of her when flipping by hand, and she just won't stay running.  I'm going to try to bake the piston, but, if that doesn't work............

I have a couple different engines I can run, 25FP, Evolution 36, Fox 35, and a 40LA.  I even have a 46AXII I could use as well if I buy a C/L venturi for it.

   I don't know what an "RST" is, but that is a very wide array of engines to consider. Normally you wouldn't consider an Fox 35 and a 46AX for the same airplane, that is a huge range of potential power, and I cannot imagine any airplane what would work well with either.

    Brett

   I don't know what an "RST" is, but that is a very wide array of engines to consider. Normally you wouldn't consider an Fox 35 and a 46AX for the same airplane, that is a huge range of potential power, and I cannot imagine any airplane what would work well with either.

    Brett

But Brett, he'll have plenty of line tension with the AX.  You know he would.  He could even go into the business of digging post holes, for people with lots of clearance around their fence lines.

I think I've held an RST in my hand once, but it may have been an earlier iteration.  At any rate, Phil markets it for "35 or 25 schnuerle".  If the 25FP is anything like the "good" 25LA, that's probably the go-to engine for this plane.

I had an FP25 on an RST. Flew just fine. Until my cousin butters plowed that sucker in leading edge deep.

On the McCoy, TJ; can you turn the plane over, so the exhaust is up, put a little oil (I use 2 stroke oil for this) in the exhaust, choke flip it 3 or 4 times and try to start it that way?

Dane,

it'll run fine if it's stone cold, but the moment it heats up, looses all compression.  I'm not kidding when I say you can send it through two compression strokes with a flip...

Oh I got ya. Sounds about right for those!

I had the same problem TJ.

An easy fix is to epoxy strips of motor mount stock to each bearer in the plane.  Use a good epoxy.  I like West Systems with a 2hr pot life.  It takes 24 hours to cure though.

Pre-glue the pieces, tape them in place.  then mask off the bottom(left side) and pour some more epoxy on to fill any gaps.  Use a heat gun to gently but thoroughly warm the motor mounts until all the  glue soaks in.

1/8 or 3/16in aluminum as shown above will also work.  It probably isn't quite as strong in crashes, and it offsets the motor to the right which isn't the best idea.  Most profiles already have the motor too far to the right anyway.  Which is a good reason to build in enough right  thrust to point the thrust line towards where the spar crosses the fuselage.

TJ,
On the McCoy if it has compression when cold you should check a couple things. First check that all the head bolts are tight, do this once it is hot or heat it with a heat gun so its close to operation temp (use a glove to hold the engine). While you are at it check the backplate bolts also. Next check the plug for tightness. I have had my plug leak after a flight on my Fox 35. When the engine was still a little warm from the first flight of the day it would not start, just pop, pop, pop. Once I check the plug for tightness it only took between 1/16 & 1/8 turn tight and all the leaking stopped and off it would go.

In desperation if the heat swelling of the piston doesn't do it, you can very carefully put the piston on a hard surface and tap the crown. The Red Head McCoy's had a domed piston and a couple smart tapes with a small hammer would push it out just a few thousands to tighten the fit. This is a last resort measure and if you rap it to hard could crack the piston. Go slow and test fit after a tap or two. 

Best,   DennisT