Ok, ran the engine sunday and the tank issue seems to be better with the dubro 14 ounce tank. I tried a few different props and saw 14,700 rpm with my TNC tach and a 10 X 6 APC. Engine does seem to be happy with the higher rpm. 10 X 8 dropped off to 13,500 and the 11 X 7 was down to 12,500. Running a bit on the rich side but at least there is an idle now and the transition is liveable to fly this thing. Going to try an APC 10 X 7 tonite to see where its at but probably fly it with the 10 X 6 and be able to land with less pitch and a slower flight speed while keeping the idle a bit higher. The engine does seem to have good power and run fine now. Too bad the carb is soooo crappy and the exhaust it comes with nothing more than a paperweight in the trash can. As soon as I can find that macs 1250 pipe it will be on there.

14 oz. is a tad on the large size, just my 2 cents. You should get plenty long runs but tuning might be a little bit of a compromise between full and not so full. That 60 might suck the fuel though the way you guys run 'em!

Thanks,

Ernie Misner

In the old days, my .60 engines with a tuned pipe could draw around 2 ounces a minute. So a 16 ounce fuel tank was just barely enough fuel to perform all of  the maneuvers for competition.  But with some planes trying to get more than a 14 ounce fuel tank inside was a problem though.

Got the maiden flight out of the way the other night and engine ran great. The only problem I had was a stuck mid range needle on the 46 size carb. Couldn't get the engine to idle real nice so, tonite I installed the carb off my OS 75 AX and will give that a try. At least I know I'll get the idle fixed as this carb works good. Also should flow some more air and get the rpms up with a bigger prop. I also have the jett tuned muffler on order. Should be able to fly this weekend..... stay tuned!

Mid range needle, is that what is usually referred to as the low speed needle or high speed needle? Only 2 on that carb, right, just curious, thanks,

Ernie Misner

Low speed needle

I keep wondering why they put a junk carb and too small of a muffler on such a nice engine.

That exhaust extension can play havoc in tuning some engines, idle mid, high or any combo. You just have to do a with and without test, re tweak the needle of course. It was just terrible on the 60NX with blue performance muffler, yet a Webra 55, APC 9X10 and red Jett muffler gained about 300 rpm with the extension.

If you get the performance muffler on that thing, it may scare you.

Jett blue muffler on order and lets hope it scares me....lol

Good!
That carb and muffler combo should be interesting. But run no more than prop than an APC 11X6 or Master Airscrew 11X7 (S-2 series)! An APC 10X8 may be faster on a long strait, but the Master may be more fun for get up and go.

Are you shaking yet?

Don't change too many things at one time. Just try a prop and see how it performs. Once you find a prop that works, then change the muffler and see if you can get an increase in performance. If the performance drops, then try another muffler. If you change too many things at once, you will never know where to go next. You will be just chasing your tail around in a circle.

Just because you are getting high rpm, doesn't mean you're getting the power. There is a balance between the rpm and the power curve.

RPMs are great, but if the prop isn't getting a large enough bite, you won't have the climb. However, if you are getting too much bite, the engine will bog down on the climb where you will lose the power you need to get to the top.

The less bite you get from the prop will get you more rpm just not the forward speed. However, too much bite will bog the engine down because it can't reach the tip of the power/torgue curve and you will again lose forward speed.

One method that can be used to find the right combination is to tie a fish scale to the tail of the plane. Try different props and see what the scale reads. Then try different mufflers and again see what the fish scale reads. Keep this up and you will find the right combination prop /muffler to get the most out of the plane.

Frank

Ok, stopped by the flying field today on the way home from a boat race and flew the phoenix. The engine now purrs like a kitten at idle with the carb from the OS 75AX tached out at 14,200 with an APC 10X7 prop and the powerbox muffler from an OS 46 AX. The transition is now instantaneous from idle to top RPM. This is fast becoming my number one airplane now. She flies very nice and the engine while still on the rich side shows good power. Next week I'll try a few more props.

I'ts a known Rx. The props I mentioned, Blue pipe (NO exhaust diverter!), 15% fuel (W/some castor!) Hot four cycle plug (OS F). The only variable is the 75AX carb, but it's got to be better than stock in mid range. Every OS carb that I swapped to a Chinese engine ran like a dream.

Hey duck two things here.
1.dont be upset ok, but the OS 46 AX with stock muffler will turn a APC 10x7 at 13,800 on 15% fuel all day long.
2. when you get the Blue muffler from jett you need to have it propped to turn no less than 14,500 and no more than 16,000 with the blue one ok. The red Jett muffler needs to be no less than 15,000. These numbers are for the muffler to do its best. Yes it will still work below that rpm but not at its best tuned range. The 10x8 and blue i think should be right around 14,800 -15,000 if i remember reading right. Now also note i have never owned one of these but basing my info off of what huys have posted. As far as the tuning range of the Jett mufflers they are based on my own running of many different engines.

One thing for all you guys to look out for on the Jett mufflers on the market is a Jett "ss" muffler. this muffler on supertigers and a few other engines is extraordinary. i will gladly pay double the price ofr one of these mufflers if you guys find one. Dub broke the mold on these so these are the "real Gold" mufflers lol. If you ever want to know the reason these are so god shoot me a PM and i will explain for you.

airraptor do you use the jett mufflers for racing or? I don't think I need all those rpms for aerobatics and 3D, just curious.

Thanks,

Ernie

Ernie yes, yes, sometimes. first off most 3d planes need large props with large low rpm engines. yes you can hover some planes with a glow two stroke but need a large one. Second this is a P7 its in the BPA/SPA range in speed so the Jett muffler fits in here well. no if going to compete and the rules say no "Jett" muffler as some of the rules do. So yes those rpms do help on uplines and so forth. now if want to fly this plane in a sport manner and dont care if not flying fast as most then sure you dont need the Jett muffler. I fly everything from fast planes to slow one. I am working on a Piece O' Cake right now. top speed 35mph lol

Duck has already ordered the Blue muffler.

With the blue muffler it will turn an APC 11X6 @15400 or MAS 11X7 (S-2 series only) @ 15100 rich'nd for flight. I did notice that I had used a 1/8" spacer so the muffler doesn't touch the fuselage. Did this help or hurt me? I don't think it makes that much difference, but I believe in full disclosure. Note an APC 11X7 is too much prop, yet the MAS just blasts off as well as it unloads and holds rpm in hard turns. The engine is a sport beast. This engine was broken-in wide open throttle, rich two stroke, Powermaster 15%.

The other Evolutions that I've had liked being broken in wide open and run hard.

The spacer probably won't matter.

Didn't know he could fly that slow