ROJett break in

[Donald Main]

Can anyone give me the correct break in process for jett .65 I have a new motor but no instructions. Thanks in advance.

[Dave_Trible]

Hi Don.  I’ve broken in all mine in this way which is pretty close to Dub’s instructions.
Use a small light prop .  For the .61-.76 I use a 10-6 wood.  The fuel should be 22-24% oil,  I prefer 50/50 mix of castor-Klotz.   Run a couple short 1-2 min. runs pretty rich and allow to cool in between.  Then I run a 10 ounce tank six to eight times with the engine at the edge of a two cycle.  Then I mount my flight prop and run 2-3 tanks at a strong 2-4 break.  It should be ready to fly.  You’ll find it will continue to grow a little stronger as you fly for awhile.  The small light prop allows the engine to run at higher RPM but stay in a four cycle,  cooler and a lot of lube.

Dave

[goozgog]

   Everyone seems to have a slightly different process.

  In my experience with my Ro-Jetts they run best on
pure synthetic. My notes say I was using Power Master
Ro-Jett 10/22 blend then Power Master Mean Green.
   Once, I accidentally got the cans mixed up and tried to
fly with the castor fuel I use in my ST.60's. Not good 
and I didn't finish the pattern.

  I tried to stick to exactly the instructions breaking in
my Ro-Jett .65 with the small exception of warming the
cylinder with a hot air gun before the very first start to avoid
that tightness at the top of the stroke until the piston
worked in a little.

  I understand that the idea is to get the cylinder / piston
up to temperature where the break in happens. Running
rich prevents this so I do short 30 to sixty second runs
where I pinch the fuel line to lean it then shut down and
let it cool. I do ten runs like this. The cooling part is important.

 The small prop is the way to go.

My Ro-jett's consistency have definitely improved as they aged.

Cheers! - K

   

[kevin king]

http://rojett.net/ENGINES/break_in_inst.htm

[FLOYD CARTER]

I should point out that the RO_Jett engines are set up very with a very tight piston/cyl fit.  Do not try "flipping" a new engine.  You might find the piston gets jammed in the upper part of the cylinder, and will not move!    Best to warm up the cylinder with a hair dryer to expand the cylinder slightly before starting.  This is not a problem after break-in.

[Walter Hicks]

Don , I have two RO Jett 67 RE and SE, Excellent engines. Once you get them broken in a bit with the correct prime one flip starts and very consistent runs like a clock. By far my favorite engines. Be careful with the fuel ( not too much Castor) they don't like that . See Brett Bucks advice on fuel as he runs the .61 which is an excellent set up. Mine are Muffler only no pipe. I sent you a PM Re Your Pat King profile Typhoon. I am in the process of building it now and have some questions . Thanks

[Brett Buck]

I should point out that the RO_Jett engines are set up very with a very tight piston/cyl fit.  Do not try "flipping" a new engine.  You might find the piston gets jammed in the upper part of the cylinder, and will not move!    Best to warm up the cylinder with a hair dryer to expand the cylinder slightly before starting.  This is not a problem after break-in.

    It's not just RO-Jetts, it is common with most AAC/ABC engines. It also doesn't go away, I have an engine I have run since 2007 that still would get stuck at TDC if you tried to turn it over with the glow plug out, or left it at TDC for any length of time with the glow plug in.  Just don't do that.

    It's not a defect. It fits up perfectly over a wide range of temperatures, and depends on being at operating temperature to have a proper running fit.

     Brett

[Leonard Bourel]

I think Rojetts run just Awesome but they need to run the way they were built to run I agree with Keith stay away from the caster and you will be a lot happier Oh and dont forget to put a few drops of after run or air tool oil in your engine after you fly I put a few drops down the venturi and remove the plug and put a few drops in the head and turn the engine over a few times to work it in then reinstall the plug I do this with all my good engines .Do not use regular motor oil for this !!!

[Dave_Trible]

Guess I better stop using the castor.  Shame tho-  three Top 20 Nats finishes with 50/50.....

Dave

[Leonard Bourel]

Ya I sure cant argue with that If it works go with it I did not mean in any way to tell anyone what to do Just saying what has worked for me Best Len

[Dave_Trible]

Oh Len that’s OK.  It’s just that these engines are just gems but I’ve heard a few stories about some not liking them and I find it’s usually because they are trying to run them in ways I wouldn’t or on fuels I’d cringe at or props that seem crazy too big to me causing them to run too hot.  Self inflicted wounds.  I’ve always found them NOT happy on flat pitch and high RPM settings.  My .40s weren’t too bad that way but my .61s, 67s, and .76s always work best for me a lower R’s and more pitch- also running cooler which may be why the castor works well for me.  To me they are sort of like a BIG,  piped Fox .35...

Dave

[Leonard Bourel]

Yup that is right The Rojetts really are true gems I never met a Rojett I didn't like