Here is a picture of a Mini Curare that I acquired from an estate sale. Apparently the plane was built but never had a radio installed. It had a OS .25 FSR installed as well a the cutest mechanical retracts. I bench tested the OS vs. my K&B .21 and the .21 had mor e power with the props I expected to run APC 8x5, 8x6. Then I installed a rear header and a Magic Muffler that is imported from Australia.
Then i spent some time installing high end JR mini servos and am pretty happy with how the upgrade turned out.
final weight is 3 pound 6 OZ! It flys great and I am in the process of getting her sorted out. The light weigh makes the landings a no brainer.
The pipe is peakier than I expected and will take a few more flight to get it running at max power.
Sparky

Ok how do I post picture from an eye pad?
sparky

Don' think it can be done... only nose pads...

a 7x6 or 7.5x6 apc will make the .21 come alive. 21-22 k on stock carb, with .40 size perry carb more like 23k rpm.. pipe pressure or header pressure is all that is needed..been there done that.

Sparky,

Lorin knows his engines! I'd give give those props a try.

On the exhaust, you might want to try a longer pipe if it stays peaky. The Macs 3.5 cc QP or MP should work well.

David

Guys thanks for the prop suggestions! I have 6 of the .21 engines (two NIB) they were the last engines done by K&B before Randy bought them out. These are "combat specials" that I used on my RCCA combat engines the carb Is .40 size! And a remote needle valve.
It does like to turn the RPM!