SJ .50 - rich or lean?

SJ .50 - rich or lean? (Full Version)

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J.T. Hammer -> SJ .50 - rich or lean? (11/17/2007 11:26:19 PM)
It has lots of power going straight up (unlimited), and trails quite heavy smoke. Pulling a split -S and coming back down full bore should have resulted in a higher speed and more rpms. However, the engine sound was 'less' and the speed seemed to even drop. Once at level flight or climbing all was normal again. And again it's trailing smoke. Temperature today was below 32 degrees. So did I have a lean run, or was it a way too rich. I want avoid the former! I was going to play around with it to determine which, but it was way too cold! This should be easy for me to figure out - maybe the wind chill affected my brain! (temperature challenged) J.T. Hammer

rmenke -> RE: SJ .50 - rich or lean? (11/18/2007 9:02:12 PM)
JT: On the surface, sounds like your are rich. What prop are you running. What is the ground rpm before you take off. No tac yet? If not find some good quality fuel tubing and run a new line if needed from tank to carb. Run the tubing out a little so you can reach in and pinch the tubilng. Note Jetts comments about keeping the tubing at the same level and length not usually being a big factor. Bring the rpm to where you think it should be. Reach in and quickly pinch the fuel line. If its rich, it will pick up rpms. If about right, no increase, or very little increase. If too lean, almost die. Its the too lean condition you want to avoid, so start out a turn or so and then go in and pinch at each new 1/8 turn. Don't get gready the first experiment. You need to learn what this engine and setup wants, and you will be rewarded. Before you go out again, go back to the Jett site and read about tuneing these engines. For some reason, you are having problems with one of the easiest engines to tune I have come across. Just says you have yet to learn that correct sound. Thats the purpose of the tac, and why its so important to have one. Yea, I seldom plull out my tac anymore. BUT, have around 50 years of playing with these things and have paid my dues. Nice thing about a good tac like TNC, it gives you the high rpm reached. You can then back off 800 or more to be safe the first time and be very close to perfect unwound in the air. When flying for a while, stay away from that diving crap. Why? Well, when you dive, the engine stays in the high rpm range much longer than a turn, and you are more likely to damage the engine diving. Pull tight pylon turns and keep the turn so that the engine does not sag in the turn. If it sags, you are turning too tight or are lean. When at the field and there are a couple of guys up and racing each other around the pylons, watch and listen to whats going on. One will probably be turning more r's than the other and is faster. Frequently the faster airplane will start to sag after several laps, will be caught and passed. His engine is going lean in the turns and needs to be a tad richer, 1/16-1/8 turn or so. Geting the most out of a engine becomes a learned art. There is always someone better, faster, stronger etc. at a given time. The guys at the top at the end of a season are frequently the same, they simply work at it harder, usually. There is always the lucky pilots for the day, super skilled pilots, factory pros etc. You may not even want to race, fine. Just be the best you can be. Its a lot of fun. ENJOY

J.T. Hammer -> RE: SJ .50 - rich or lean? (11/19/2007 12:00:01 AM)
rmenke My first rc airplane was a Berkley j-3 cub in 1960 with a veco .19 (single channel with escapement), followed by many cg falcons, skylarks. In subequent decades my engine of preference became O.S., although I have tried almost every other make. The fs, fx, and ax series have all been used to great extent. I havn't bothered to use a tac for 20 years or so and don't own one now. I have a reputaton of never having engine problems and never use a starter. The SJ .50 is just a tad different so am getting used to it. One thing different is the broad tuning range of the needle which is relatively non-critical. With the O.S. the sweet spot can be located easily within 1/8 of a turn (back and forth turning). I only have 5 flights on the Jett so far and 4 of them have been fantastic. I enjoy flying fast and low and turning left, and this can bite you in the butt once in a while too. I find at my age, 64 (crap, now everybody knows), I don't have quite the -----I once had for furious flying. However, I never turn down a challenge either. I also believe the Jett was too rich on my last flight. If it's not too cold tomorrow I'll try her again. My remote needle is located on the outside of the fuse so the pinch line method will work fine. The prop is an apc 10/6. Come on rmenke, a nice dive from altitude to screaming low across the field is a beautiful thing! Yes, I guess I'll have to buya tac The Jett deserves it. Have great day. jt

MJD -> RE: SJ .50 - rich or lean? (11/19/2007 1:34:35 AM)
quote: ORIGINAL: J.T. Hammer rmenke My first rc airplane was a Berkley j-3 cub in 1960 with a veco .19 (single channel with escapement), followed by many cg falcons, skylarks. In subequent decades my engine of preference became O.S., although I have tried almost every other make. The fs, fx, and ax series have all been used to great extent. I havn't bothered to use a tac for 20 years or so and don't own one now. I have a reputaton of never having engine problems and never use a starter. The SJ .50 is just a tad different so am getting used to it. One thing different is the broad tuning range of the needle which is relatively non-critical. With the O.S. the sweet spot can be located easily within 1/8 of a turn (back and forth turning). I only have 5 flights on the Jett so far and 4 of them have been fantastic. I enjoy flying fast and low and turning left, and this can bite you in the butt once in a while too. I find at my age, 64 (crap, now everybody knows), I don't have quite the -----I once had for furious flying. However, I never turn down a challenge either. I also believe the Jett was too rich on my last flight. If it's not too cold tomorrow I'll try her again. My remote needle is located on the outside of the fuse so the pinch line method will work fine. The prop is an apc 10/6. Come on rmenke, a nice dive from altitude to screaming low across the field is a beautiful thing! Yes, I guess I'll have to buya tac The Jett deserves it. Have great day. jt Nose down - more fuel head pressure - strongish running rich mixture goes richer - rpm drops. Straight up, lots of power, heavy smoke - reduced head pressure, harder to draw fuel - mixture leans - power picks up and engine pulls hard (but still sounds rich from your decription). Level flight - richer than 2, leaner than 1 - running pretty strong but with heavy smoke - on the rich side. That's how I see it, doesn't sound like a mysterious situation. Broad needles are good - if it runs as you describe, land it, lean it a touch, take off and assess it. Repeat until happy. All engines deserve a tach! They're cheap and tell you more than your ears will sometimes pick up. I'm a musician and have a good ear for engine pitch and mixture, but now and again I get fooled and the tach brings me back to home base. With the Jett, then you can follow the instructions to the letter regards tuning, then complain to Bob when it still acts up.. [:D] (kidding..!) MJD

still4given -> RE: SJ .50 - rich or lean? (11/19/2007 8:42:02 AM)
You didn't say if the smoke trail was still there in the dive. One thing came to mind as I read your first post, only because I had it happen to me a while back. I had a fairly stiff clunk line in my tank and when flying straight down, after burning off some of the fuel, the clunk would be out of the fuel level in the back of the tank because the fuel line wouldn't flex enough for the clunk to fall forward and stay in the fuel. I'm not sure if that is your problem but it could be. Most likely it is what others have already stated but not if it is going lean in the dive. Blessings, Terry

J.T. Hammer -> RE: SJ .50 - rich or lean? (11/19/2007 1:25:37 PM)
Thx for the advice guys. It's 0 degrees C. (32 for you in usa), but am going to the field to try your suggestions. If I don't freeze to death I will let you know what happens. Do you know what the chill factor is at that temp while tuning the engine behind a prop turning Jett speed - burr!!! jt

J.T. Hammer -> RE: SJ .50 - rich or lean? (11/19/2007 8:35:16 PM)
Well. I managed 2 flights this morning in spite of the cold. Used the pinch the line to the carb to access rich or lean (and yup it was rich). Found the sweet spot and had 2 very nice flights. That's 7 flights on the Jett, in addition to the break-in time. Winter has all but closed in here now, so am putting it all away till spring. I'll put a bit of 'after-run'oil in the Jett so it can be stored safely for about 5 months. Thx again for all your help! JT

rmenke -> RE: SJ .50 - rich or lean? (11/19/2007 9:07:14 PM)
JT: Would feel sorry for you if I were not 10 years older (sob-snivel). Anyone who can get a Veco 19 running well enoug to pull that CG Jr. Falcon up is doing just fine thank you. Sounds like you have a good handle on things except for the affection for the OS junk. I have never forgiven them for the pealing cylenders and still cheepie bearings so their net is another $.50 cents. Now, 4 bolt cylender heads? Seems to always happen when a good solid customer careing business is sold to a bean counter. Must be getting cranky in my old age. Never give it up!!! This year at the start of our club racing searon, the kids actually had the balls to serve notice on me. "Your done, kaput, finished, seen your best old man, etc." Well, they stoped the season early this year in Oct. "due to weather". Wonder if its really just no way to catch the old man in overall points, so we give up? Gonna have lots of fun with this this winter. ENJOY

MJD -> RE: SJ .50 - rich or lean? (11/19/2007 9:58:16 PM)
quote: ORIGINAL: J.T. Hammer Thx for the advice guys. It's 0 degrees C. (32 for you in usa), but am going to the field to try your suggestions. If I don't freeze to death I will let you know what happens. Do you know what the chill factor is at that temp while tuning the engine behind a prop turning Jett speed - burr!!! jt Sure do... that's why I already stopped flying glow for the year, being an hour or so NW of you! MJD

J.T. Hammer -> RE: SJ .50 - rich or lean? (11/20/2007 2:13:09 AM)
rmenke Holy cow; you're old as dirt. Makes me feel young again! Wish we could race, but you'd probably drag that smokin' beast from your car - the one with the .60LX on it. On the other hand, perhaps you could beat me with your 'slower' one. Oh well; I'm the only one in our club with a Jett, albeit, only the SJ.50. But if I put it on something small and sleek, I think it will outrun anything here. If not I'll have to consider the 60LX. I know you hate O.S., but the one's I mentioned are user friendly, and I've never had a failure. My .50 SX worked real well for me and I worked it pretty hard, and the guy I sold it to, liked it too. I think I mentioned earlier that I had rwo .32 SX's on a little twin this summer (Twinstar). It really boogied and the sound was awesome. I always take the muffler baffles out of the O.S. engines. Well, I know I won't change your mind. By now you are firmly set in your ways and thinking! I'm going to bed now. It's 9 o'clock and we seniors have to get our proper sleep! And to all a good night! JT

rmenke -> RE: SJ .50 - rich or lean? (11/20/2007 2:26:04 AM)
JT: I do have a sence of fair play. Would start with the old slower 35, below 140, then to the intermediate, above 140 and of course, bring out the king 60LX setting in a streemlined Q-500 thingy that flat scares even me. It does outrun the locals badly, bery badly, but thats its intended design. If you can't beat them fairly, beat them unfairly!! I know, a personality flaw. ENJOY

J.T. Hammer -> RE: SJ .50 - rich or lean? (11/20/2007 1:34:53 PM)
I don't blame you for leaving the king 60lx in the car most of the time - would scare me too. I don't know about you, but sometimes after a particularily fast harrowing flight, I experience a general kind of weakness throughout the body (mabey an adrenaline high). Have a great day. JT

bob27s -> RE: SJ .50 - rich or lean? (11/27/2007 4:55:51 PM)
Im glad to hear things are working ok. Let me know when things thaw out :) Bob

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