rt3232

My Feedback: (6)

Ok I have a 26 cc (Chinese) engine with about 15+ hours on it and it started to lose RPM, so it was recommended to in stall a Bowman ring, witch I have now done, following Mr. Bowman's instructions I am in the process of break in using a 32;1 mix using a Valvoline 2cycle oil certified as meeting TC-W3 and 100 ave gas. the instructions did not mention scuffing the cylinder wall,

So the Question is do I need to run the engine on the rich side for the first few tanks of fuel, I got 18 minutes of run time on the first full tank, in 3 separate runs of 6 +/- 1, on the first run I had to richen it to get a 2K idle, and stayed below 1/2 throttle. Second run the same idle and after about 4 minutes short burst to full throttle, same thing on third run letting engine run at about 2.5 K before shut down. have been holding a paper towel under exhaust ports, not much residue is showing.


Cheers Bob T

karolh

Unlike ringed glow engines a gas engine should not be run overly rich. For completion of your ring break in I suggest that you tune the engine for max rpm and slightly richen the high end to reduce max.rpm by say 300, check for a reliable idle and finish breaking in the ring by putting the engine in a model and flying without doing any sustained full power flying for the first gallon or so.

dirtybird

My Feedback: (5)

Ask Frank. He knows more about it than anyone on this forum

rt3232

My Feedback: (6)

First it is in a plane, and the bird is just a bit big for the engine but once it is up on the step it flies fine, not a lot of vertical but for me it is a great flyer nice big loops, rolls, hammer heads, inverted just no 3D stuff, but it does require full bore most of the time.

It now has 30+ minutes run time on the ground, great throttle response, idle is at 1880 to 2010 running a xora 18 X 8 and have only gone to full bore for about 30 seconds at a time and only after the engine has run for 2 to 3 minutes tack's about 6400 +/- 50, so it could be over propped, I think this engine should be turning 7K+ will install the cowl, and re check top end. may try a vora 17 X 8 and see how that works.
Weather hear is predicted wind rain next 2 days.

av8tor1977

My Feedback: (6)

I agree to go ahead and fly it, and I would use a 16 or 17 x 8 prop on it. Later, you might also try an 18 x 6 from how you describe your plane.

Frank does indeed recommend gently scuffing the cylinder with #400 or 600 sandpaper and solvent before re-assembly with one of his new rings, as do I.

AV8TOR

rt3232

My Feedback: (6)

Well I got another run on it last evening about 10 more min. when tis engine was in my vary old 25years dragon lady @ 10 lbs it was vary strong, but in thi new bird a G/P 300 @ 13, so will see

AV*TOR thanks for the feed back

Cheers Bob T

karolh

I agree with AV8TOR that an 18x8 prop is a bit much for your engine and based on the plane you are using it in I would suggest a 17x6 or 18x6 and see which one works best.

rt3232

My Feedback: (6)

Karolh

Went to my LHS they were out of 17 X 6 so I am going to see what a 17 X 8 will do, the shop will have the 6 pitch by Friday so may just go by there after work

Cheers Bob T

rt3232

My Feedback: (6)

Well guys Got a chance to run the engine with the 17 X 8 with the smaller/lighter prop had to do a bit of tuning What I would call clicks or about 2 points on a 32 point compass, low needle 2 clicks leaner, and 3 on the hi needle Idle remained solid at 1980 to 2010 nice smooth transition and I picked up a full 1,000 at full throttle 7400 to 7500 + but still not running more than 30 to 45 seconds at full bore, and still no cowl.

So all seams to be good for now.

Cheers Bob T

av8tor1977

My Feedback: (6)

Sounds like it is time to fly it!

AV8TOR

rt3232

My Feedback: (6)

Your right cowl is on, but have not checked if it makes a difference, Had to day off but the weather is the pitts wind @25 gusting to 30, good thing is I got some of my honey dooo's done. So tomorrow if the wind lets up to 10 or under will go flying.

cheers Bob T