stunthanger.com

Engine basics => Engine set up tips => Topic started by: Mark Mc on August 16, 2017, 11:41:59 PM

Title: OS Max 15 requirements?
Post by: Mark Mc on August 16, 2017, 11:41:59 PM

I have a 1975 OS Max 15 that I want to use for a trainer.  I say it's a 1975 because I looked on the O.S. website and that's what the website shows.  I can't find any documentation for the engine, so I'm asking here.  What would be the best fuel to use on this engine?  Does it need the higher castor content, or did the '75 OS engines run okay on mixed castor and synthetic?  Also, what is the best plug for this engine?

I'm going to put this on a SIG Buster for a trainer, so I want it to be slower and controllable.  I'm thinking of using an 8x3 or 8x4.  What's the best recommendation from the experts here?

Mark

Title: Re: OS Max 15 requirements?
Post by: RandySmith on August 17, 2017, 12:04:34 AM

Quote from: Mark Mc on August 16, 2017, 11:41:59 PM

I have a 1975 OS Max 15 that I want to use for a trainer.  I say it's a 1975 because I looked on the O.S. website and that's what the website shows.  I can't find any documentation for the engine, so I'm asking here.  What would be the best fuel to use on this engine?  Does it need the higher castor content, or did the '75 OS engines run okay on mixed castor and synthetic?  Also, what is the best plug for this engine?

I'm going to put this on a SIG Buster for a trainer, so I want it to be slower and controllable.  I'm thinking of using an 8x3 or 8x4.  What's the best recommendation from the experts here?

Mark

Hi Mark,  if the motor  is not ran much use a fuel with at least 25% oil  part castor, a 50 50  blend will work well in your  15,  I would start with 10 nitro.  Use a  short  HOT plug, or  an Enya #3

Randy

Title: Re: OS Max 15 requirements?
Post by: GERALD WIMMER on August 18, 2017, 05:16:37 AM

Hi Mark
I use 4 x OS 15 70's era engines on my two sons profile scale trainers and stunt trainers as well as 2 steel fin OS 15's on my twin engine stunter. Great little motors but don't let them run lean as they will loose their compression real quick , seems that most small OS engines of this period have soft piston/liner material. I have bought 2 OS LA15 for my wife's Brodak Tiger Cat kit and will be keen to see how they compare . Prop's I'd use an 8x4 prop and no. 8 OS plugs fit fine (as they are medium length). Regards Gerald