I use the standard Poulan coil, plug wire, plug lead and plug. I have absolutely no problems with RFI but I took some time to eliminate possible problems:
1. Mount the Rx as far back as possible in the airframe
2. mount the throttle servo at least 10" back from the engine and link to the engine using a plastic link rod (I used a sullivan gold'n'rod) as a metal rod will transmit RFI
3. keep the rx aerial well away from the servo wires and battery wires and twist all servo cables to prevent RFI.

I use a futaba 138 dual conversion Rx, and a futaba T7CAP Tx, nothing fancy.

The engine has a normal Champion RCJ7Y, the one the engine came with.

I have machined out carbs before, you just make a mandrel to mount them on the back face in a lathe then get turning. Careful though, the carb still needs a venturi shape to help fuel into the airstream. Often better to just bolt on a bigger carb.



I have a WA200 carb (28 in the throat) that is 15.8mm bore at the engine end, 11mm at the narrowest point. Its unmodified as it seems fine but does need the bellmouth.

Onto your other questions:
Compression. This engine is still very conservative, it gave 200rpm but of course it also dropped the port heights 0.4mm doing this. The smallest chage probably, but you need it once you get the ports modded to get the best out of the engine. Tuning is a balancing act, there is no point just doing, say, the ports, or the compression, or the carb, as each will not make a lot of difference, but together they work to help each other give you more power.

As far as the bearings go, the engines are fine, I've run 20hp 20,000prm engines on rubber sealed bearings for hours with no problems. My main concern would be that the engine is designed to run with no end load on the crank hence has ball bearings. With a prop on you all maybe 11lbs of end load and ball bearings are not designed to take end loads.......

For machining I did the exhuast and inlet with a series of coarse and fine files and the transfer ports with a dremel 35000rpm hobby tool with a rotary burr in. Took about 2 hours in all. The liner is just the same casting as the barrel, its an AAC engine so not hard at all.

As I said, there is no particular magic change, you need to do them all for it to work. Again bear in mind I did this as a mild tune and the PTA and PAA numbers are just for a normal engine, not a full race version.

You can make the same exhuast I did the 8500 tests with, just take the outer off your standard exhuast. Putting the long exit pipe on took 300 revs off the engine but I've been making a new exhuast tonight, pics will be on the RCMF site later.

Hope that helps. Just a note, I could not get mine to run with glow power though on 98% gas, 2% oil, but it seems good on ign so I'll probably stick with that.

Cheers,
Rich