O.S. 91 problems
 

After many efforts to get my first D/F engine properly broken in and ready for use I am starting to wonder if there is something wrong with it. I bought it "new in box" and it appeared to have never been used. It seems like I can never get it to run smoothly and reliably like an O.S. prop engine. In the last run it kind of started sounding a little different and now I am afraid that I might have over leaned it - or damaged it somehow - although I have always made sure there was smoke and I don't think I have ran it at a high rpm for more than a few seconds !! How can I check to see if I have burned it up or ruined it somehow ?? What are some tests that I can do? Here is my setup:

OS 91 Small Head / Dynamax Fan / JMP Pipe / McCoy M8 Plug
Morgan 10% Glow Fuel

Mounted in Y/A F-16C

PLEASE HELP !!

Frustrated.....

reply
 

First should use MC9 plug
Second use Wildcat D/F fuel.
This should solve most of your problems.

Brandon

OS 91 problems
 

You need to run fuel formulated for D/f engines. If this is standared Morgan fuel it only has 18% oil. If it is Cool Power it only has synthetic oil which is a no no. Use only Wildcat Jet fuel with 5% nitro as it has both synthetic and castor oil. Your engine is overheating due to the lack of oil. Run two tanks of good fuel through the engine with the throttle wide open and the mixture super rich to break it in. Then fly it and keep the mixture on the rich side. An inflight mixture needle would also help

Morgan also makes a fuel for d/f called Jet 7% which will also work

O.S. 91 problems
 

jetflyrf86,


thanks for the help.... should I check the head? If it was burned up or damaged how would I know?

Thanks

O.S. 91 problems
 

while your are checking the head assuming everything is ok get some blue loctite and put on those head bolts,and block bolts also. belive me this will help you keep it together!!
scott
p.s. i have had really good luck with the wildcat 5% 75 -100 runs with out failure.

O.S. 91 problems
 

Im running Byrons 5% in mine, runs like a champ!

Byron Fuel
 

I use Byrons 5% too. I have always added a little castor but, now I have taken to JackJet's suggestion to add about 8 oz per gallon of castor. I'll have to say the engine appears to be staying cooler and the runs more reliable with less leaning and longer plug life....

Rod