Hi Randy: I recently bought a GP-40 that you reworked with a hardend piston and whatever else you do to them. Bill H. told me to use 22-23% oil 50/50 5-10 nitro and said it would take the better part of a gal. to break in. What breakin proceedures should I follow ? He said fly with a 11-5 and experiment from there, should I use a 10-5 for breakin ?  Thanks

Hi Randy: I recently bought a GP-40 that you reworked with a hardend piston and whatever else you do to them. Bill H. told me to use 22-23% oil 50/50 5-10 nitro and said it would take the better part of a gal. to break in. What breakin proceedures should I follow ? He said fly with a 11-5 and experiment from there, should I use a 10-5 for breakin ?  Thanks

Hi

If I were doing the breakin and  could wait, I would untill  some  warmer weather is here. You can run into some trouble if the piston sleeve fit is tight in very cold weather.
Then use a 10 x 4 prop and run the engine 4 ounces at a time, start with it in the fastest 4 cycle it will run in, and  turn the needle just into a 2 cycle for about 10 seconds, then back into a 4 cycle for 30 secs or  so, then back to a 10 sec 2 cycle.
After a few runs like this, take the 2 cycle up to 15 or 20 seconds at a time. Be sure to put in a """NEW"""  glo plug before you fly the engine in an airplane.
I would start with 24 to 25% 50-50 oil  and  5% nitro, using more only if it needs  it
People have used props from 11x 4 bolly , 11 x 6 bollys, 11 x 4 3 blades  11x4  ,11x 5  BYOs  and more, Depending on the airplane, just use  what works  best.
Remember the prop pulls the plane  and prop pitch determines the  lap speed, not the needle

Regards
Randy

Regards

Randy

Leester:
Bill H recently had two Randy Smith Mag 40s for sale.  I suspect that you bought one and I bought the other.  I, too, was going to query Randy about break-in procedures for the motor, but you beat me to it.  Thank you for doing so.
To Randy and Bill, thank you for your advice.
Peter Hess
Canton, CT

Hi, Leester:
My Mag 40 is slated to go into a profile Cardinal.  Just when that might be finished is subject to some question because of the other projects ahead of it, but hopefully it will be ready by late spring or early summer.
In the meantime I will get it ready for the break-in bench and wait for a warm day - - and that could be a long wait - - to start putting some time on it per Randy's instructions.
What use do you see for your Mag 40?  Do you yet have any notion what you might use for a muffler?
I look forward to keeping in touch with you with regard to these motors, although being in Connecticut it might be some time before there is anything to report.

I have had a copuple/three of theses....terrific pieces with great runs.....
I have best luck with a 10 1/2 X 4 1/2 APC running a rich 2 cycle at launch...

Manuel: As best I can tell (Crude measurement device) is 5/32".

I started to break in the Aero Mag today using a 10-4 prop and Sig 5/20 fuel didn't have 23-24 oil content available. I think the NVA is a ST it doesn't go through the venturi, it's in front. The first tank was spent adjusting the needle on the secound tank I was able to get it set fairly well. On the third tank I couldn't get it to lean out it was running a med. 4 the only way to lean it was to pinch the line or put my finger over the tank vent. I closed the needle all the way and it still ran the same. The first thing I'll do is get a PA NVA from Randy when he gets back from VSC, I don't know what would cause this ??

I started to break in the Aero Mag today using a 10-4 prop and Sig 5/20 fuel didn't have 23-24 oil content available. I think the NVA is a ST it doesn't go through the venturi, it's in front. The first tank was spent adjusting the needle on the secound tank I was able to get it set fairly well. On the third tank I couldn't get it to lean out it was running a med. 4 the only way to lean it was to pinch the line or put my finger over the tank vent. I closed the needle all the way and it still ran the same. The first thing I'll do is get a PA NVA from Randy when he gets back from VSC, I don't know what would cause this ??

Hi Leester

I just got in from the  VSC in Tucson..great time..  Sometimes people run the needle in too hard and it bends or breaks  out the orifice hole in the Spray bar also, something is wrong and you need to fix or replace that NVA in the engine. It wouldn't do any good to run the engine in a  too rich  mode
Please let me know if I can help you
regards
Randy