AP Hornet .09 tuning?

[KeithLuneau]

Hi. I've got an AP Engines Hornet .09 on a Hobby Shack Schoolboy. It's got about 10-15 flights on it after break in. I've ran 25% Sig fuel, K/B RC Short glow plugs, and a 7x4 prop since day one. I've always had problems with it not wanting to idle. I can adjust the needle at wide open throttle, and it's way too rich at idle, and bogs down when trying to throttle up. If I lean it until it has good idle and throttle responce, it's way too lean at the top end. It's a single needle carb, with no adjustment for idle mixture.

Any ideas on how to solve the problem? It's a great little engine, has good power and is quiet, but I just can't keep it running good enough to enjoy flying with it.

Thanks for any help,
Keith

[DICKEYBIRD]

About all I can think of would be to add some head gaskets to reduce the compression which will cause a corresponding need for a leaner needle setting. You might also try less prop load and lower nitro as well....anything that will create the need for a leaner needle.

Andy W. drills his Norvel carbs and adds an adjustable airbleed to clean up the low end mixture but I wouldn't try it unless you have some machining experience.

[easytiger]

And that engine looked so great, I know.
I had one, could not get it to idle. Did not drill an airbleed, but tried head gaskets and all that. No joy. Fine at full power, though.

[KeithLuneau]

I have tried lower nitro, 10% that I use in my bigger engines, and it didn't help much. I've got a Master Airscrew 7x4 on it now, would an APC 7x4 have less load, I have one now as a spare. The blades are alot narrower than the MA prop. I thought of adding an airbleed, but not sure I want to try it on this motor. I don't have anything to thread the hole for the screw with anyway.

[Lynn S]

Are you getting good fuel flow?
My .061 sure runs nice.

[easytiger]

The 061 is a different engine.
I would suggest getting the norvel 074 instead. I just had no luck with this puppy. A friend of mine got a pair, for a Ju-188 he built, and tinkered endlessly with no joy on the idle. He's just now buying a pair of 074s to replace them.

[1705493]

Keith,

If you're willing, I could try adding an adjustable airbleed to your AP .09 throttle. No charge, curious to see if it would help.

But, I do agree that the Norvel .074 would be a good replacement. Much lighter and more powerful. And, despite not having an adjustable airbleed, it throttles amazingly well. The trick is that the main needle has a very broad range and can be used to fine tune the low end. Something that the .06 doesn't do too well without an adjustable airbleed.

[maboumrad]

I have the AP Hornet .09 and stick it to a 1/2 A Hummer but there is no power, I put a 7X5 maybee I should try a 7X4. I live in Mexico City and it is very high and that doesnt help on power. So if I put the 7X4, 40% nitro and get head gasket of should that help for more power? Please help, my plane looks like a RC car. :(

[on pipe]

I hate to rain on a parade, but the only time my AP 09 flew was when I tossed it in the trash can... Although there are much better quality products coming from China these days, this is not one of them. Low powered, (IF you get one with a decent piston/liner fit, and using the same case as the 15, they are pretty heavy. Of course the Norvel 074 would be better, but even the OS 10, or the Enya 09 would be a much better choice. Just my two cents. (can you tell I had a crappy one?) Ross

[maboumrad]

thanks for you response. Maybee throw it to the trash will be a good idea, because it is worst to keep loosing time in that crap. I will make a last try to put some 40% nitro and if it doest work I will put nitro all over the engine a put a match over so it burns for ever and then put it on the trash- :)

[bverwolf]

I have an AP 09 also. I know some people have had good luck with them, but unfortunately I was not one of them. It started horrible from day one. I thought maybe it was just the nature of it and learned to live with it. I flew the thing for maybe 20 flights using Byron 15% fuel with enough castor added to make the oil around 20%. I then noticed a very significant amount of play in the connecting rod. I removed the backplate to find the bottom end of the connecting rod wallowed out significantly. I ordered a new con rod and the new one had brass bushings in it where the stock one didn't. It seems to me that there is a great degree of quality difference in these little engines. Mine also doesn't idle well but luckily the plane I fly it in uses full throttle almost all the time. Good luck with yours. :)

Ben

[Rube Goldberg]

Sometimes you get a rainbow after a rain.

There are 6 (six) members in my club that are flying identical planes/engines in a "competitive" nature: the Herr Engineering/Sig Little Extra equipped with the AP Hornet 09 engine. We started this "series" about 6 months ago, bought the engines from HobbyPeople.net and all 6 of them run fine on 15% nitro with an APC 7X4 prop.
Realize, an acceptable idle speed is about 5,000 RPM. You won't nor should you expect an 1800 RPM idle like your 4 stroke engine. At 5,000RPM the plane will not move forward on pavement. Peak RPM is almost 14,000. We've flown up to 5 at a time with a LeMans start.

Rube

[Glue Gun]

I got an AP .09 engine on sale for $38 from HobbyPeople and have been very pleased with it. Starts everytime with only a few flips. Right now I have it on a pbf made out of blue foam. It has more than enough power to hover, roll, loop etc. I'm using Omega 10%, a Du-Bro 2 oz tank, an APC 7x4 prop and a Thunderbolt short glow plug. Be sure to tighten all the screws and the back plate before you run it or you won't get proper fuel draw. Maybe I will try the AP .061 when it goes on sale.

[Glue Gun]

The AP .061 has just gone on sale at hobbypeople.com
Check it out.



Go glow or go home.