*** CLUB SUPER TIGRE ***
11-03-2015, 08:27 PM
#1802
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Whether it's been luck or skill I've never struggled with the stock ST carbs. I also love those Bisson Pitts style mufflers. The Four Star is the first ST muffler I've used on a ST above .90 size. It runs great but appears to leave more oil on my plane. Obviously a directional issue.
11-03-2015, 09:10 PM
#1803
I too have had great success with the SuperTigre Mag carbs. Only until recently did I put an Enya XF-IV Heli carb on my S90 - not because the ST Mag carb was bad but because the Enya was bigger. Just did it as an experiment. It has not been tested in this fashion yet.
I am a big ST fan, just not of the BIG ST engines (above .90) mainly because I have no use for them.
I am a big ST fan, just not of the BIG ST engines (above .90) mainly because I have no use for them.
11-03-2015, 10:09 PM
#1804
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I'm with you 1Q. My interest is there but the transport and cost above 1.20 sized planes, props, servos, etc trumps my curiosity. I mostly build and fly in the .40-.60 range. Fortunately I have 22 ST engines in stock.
11-04-2015, 03:46 AM
#1805
I currently own 5 Tigres. They all run sweet. My G51 needs a new liner though. The previous owner didn't store it well and the liner corroded and pitted in the middle. It runs pretty good despite the pits, but the compression is a little lax even with a Bowman ring in it. Still a good engine.
11-04-2015, 07:31 AM
#1807
I'm keeping my eyes open for a new liner. It runs good as it is, but the compression is a little soft. I've run it on glow fuel and diesel and it does well on both. I think it turned a 10x6 APC to 14,500rpm with a round spraybar. It picks up 500-800rpm with a flat spraybar.
11-04-2015, 03:55 PM
#1808
Ringed motors never seem to have compression. I have a .51 on my Seamaster. Pretty happy with it. A flying buddy has an old Webra Silverline .40 with, I am guessing, easily 100's of hours. No way of telling where the compression part of the stroke is, and it takes the starter a long time to get it going, but it keeps on running. He has flown it a lot for many, many years, and I doubt he will put a new ring in any time soon. It would not hurt to look for a new liner for yours though, good to have spares for the orphans.
11-04-2015, 07:19 PM
#1809
Ringed motors never seem to have compression. I have a .51 on my Seamaster. Pretty happy with it. A flying buddy has an old Webra Silverline .40 with, I am guessing, easily 100's of hours. No way of telling where the compression part of the stroke is, and it takes the starter a long time to get it going, but it keeps on running. He has flown it a lot for many, many years, and I doubt he will put a new ring in any time soon. It would not hurt to look for a new liner for yours though, good to have spares for the orphans.
11-07-2015, 04:43 PM
#1812
Looking for some advice. I'm trying to tune an older Super Tigre 40 engine and have several questions:
1) When doing the pinch test at WOT the RPMs should slightly increase as soon as you pinch the fuel line, right? If it doesn't increase then mixture is too rich?
2) Is there a pinch test to do in order to set the low speed needle setting?
3) What exactly does the "idle stop screw" do and how should I set it?
Here are pics of the engine and carb:
1) When doing the pinch test at WOT the RPMs should slightly increase as soon as you pinch the fuel line, right? If it doesn't increase then mixture is too rich?
2) Is there a pinch test to do in order to set the low speed needle setting?
3) What exactly does the "idle stop screw" do and how should I set it?
Here are pics of the engine and carb:
Last edited by AllModesR/C; 11-07-2015 at 04:50 PM.
11-07-2015, 05:11 PM
#1813
Looking for some advice. I'm trying to tune an older Super Tigre 40 engine and have several questions:
1) When doing the pinch test at WOT the RPMs should slightly increase as soon as you pinch the fuel line, right? If it doesn't increase then mixture is too rich?
pinch the fuel line as close to the carb as possible and only momentarily. Always start rich and work lean. If rpm doesn't change, it's peaked. If rpm drops, it's lean. If rpm raises, it's rich.
2) Is there a pinch test to do in order to set the low speed needle setting?
You can use the pinch test to set the idle, but I don't find it as reliable. Rather, set the idle mixture so you can get a slow smooth idle. 2,500rpm is good. Do not tailor the idle needle for the transition - that's what the spraybar adjustment is for. Run the spraybar straight in to start with. If the midrange is too rich and burbly, adjust the spraybar by aiming the fuel inlet nipple lower towards the engine mounting lug.
3) What exactly does the "idle stop screw" do and how should I set it?
The idle stop screw sets how far open or closed the throttle barrel is at low throttle. It's best to set it just tight enough so the barrel will completely close. Set your radio such that the throttle stick closes it to a good idle speed with the stick at its lowest position and the throttle trim switch at neutral position and when you move the throttle trim switch to lowest setting kills engine.
Here are pics of the engine and carb:
1) When doing the pinch test at WOT the RPMs should slightly increase as soon as you pinch the fuel line, right? If it doesn't increase then mixture is too rich?
pinch the fuel line as close to the carb as possible and only momentarily. Always start rich and work lean. If rpm doesn't change, it's peaked. If rpm drops, it's lean. If rpm raises, it's rich.
2) Is there a pinch test to do in order to set the low speed needle setting?
You can use the pinch test to set the idle, but I don't find it as reliable. Rather, set the idle mixture so you can get a slow smooth idle. 2,500rpm is good. Do not tailor the idle needle for the transition - that's what the spraybar adjustment is for. Run the spraybar straight in to start with. If the midrange is too rich and burbly, adjust the spraybar by aiming the fuel inlet nipple lower towards the engine mounting lug.
3) What exactly does the "idle stop screw" do and how should I set it?
The idle stop screw sets how far open or closed the throttle barrel is at low throttle. It's best to set it just tight enough so the barrel will completely close. Set your radio such that the throttle stick closes it to a good idle speed with the stick at its lowest position and the throttle trim switch at neutral position and when you move the throttle trim switch to lowest setting kills engine.
Here are pics of the engine and carb:
11-07-2015, 09:05 PM
#1815
Your arrow is pointing at the idle stop screw. The idle needle is in the throttle arm and the spraybar/midrange adjustment is in the main needle assembly. You loosen the two screws slightly and rotate the spraybar a little bit. Warning: Any adjustment on an ST carb should be made in very small increments. It is very easy to miss the sweet spot. Keep the nitro low too - these older Tigres were designed for 0-5% and as such higher nitro can cause all sorts of problems. The manual may say 5-15% nitro is okay, but without adding head shims, it isn't. At least if you're close to sea level. If you're at 5000' ASL, 10-15% may work okay.
Last edited by 1QwkSport2.5r; 11-08-2015 at 02:13 PM. Reason: added information.
11-07-2015, 09:57 PM
#1816
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Not much with tx servo cut kill switch . You can even remove it if you wish . It just lets you leave the throttle open a smidge to whatever u wish for idle with the carb arm pull all the way back ( or forward , cant remember which ) . Screw it in and out a bit and u will see what I mean .Picked up a NIB 40 at a local auction .$60 , usual price new is around $140 . Cheers the pope
11-08-2015, 05:30 AM
#1817
Sincerely, Richard
11-08-2015, 05:36 AM
#1818
Every one one of my STs have the spraybar straight in. The 90 was the only one I ever touched the spraybar on. The rest run fine as-is.
So yes Richard is correct that some engines want the spraybar adjusted enough to have the fuel nipple pointed at the rear engine mounting lug hole.
Last edited by 1QwkSport2.5r; 11-08-2015 at 05:43 AM.
11-08-2015, 05:48 AM
#1819
11-08-2015, 06:06 AM
#1820
I was running my S90 yesterday too. But lots of smoke. Tried an experiment. Enya XF-IV Heli carb on the ST S90 with red Jett .90 size muffler on a 12x6. Stock ST carb, 5% fuel and Jett muffler gave 13,900rpm. Enya carb with 10% fuel (Enya carb is about 1mm bigger than ST carb) gave 14,000rpm but horrible throttling. Besides, this .90 hates nitro. It tolerates 5%. I had to run it 1k richer on 10% to not get the frying egg sound. I know, I know... That's a lot of rpm for a .90. The tuned muffler rpm range is 12-15k. This muffler would likely be better suited for a .61. Still keeping my eyes open for a .61 ABC made in Italy.
11-09-2015, 06:08 AM
#1821
The fuel I am using has 10% Nitro and I still have two gallons of it so I really don't want to spend more money on fuel, bummer. I was tuning it yesterday and it runs well at WOT throttle but likes to die when idling. Then when I transition from idle to 1/4 or 1/2 throttle it hesitates for a second or two. Any ideas what I should do? I am using an OS number 8 glow plug and somebody suggested I should switch to a number 6 due to the cooler ambient temperatures.
Last edited by AllModesR/C; 11-09-2015 at 10:36 AM.
11-09-2015, 06:33 AM
#1822
If it hesitates, and it wants to die, it is too lean, and the low speed needle needs to be richened. If it hesitates and burbles, and spits out fuel from the carb, it needs the low end needle leaned out. That is the basic rule when throttle is given. 1/4 turn adjustments at a time is a good rule. Then if it is the wrong way, you know how much to go back to correct it to the way it was.
11-09-2015, 09:25 AM
#1823
I'd stick with a hotter plug. My Tigres prefer hot plugs. Don't change glow plug heat ranges based on ambient air temp. Air temp has little to do with the glow plug heat range but rather the fuel being used most of the time. Less nitro needs a hotter plug. More nitro needs a cooler plug - sometimes.
As aspeed said, open the idle mixture a little bit. If after running wide open for a time and bringing it back to idle causes the idle to 'hang' for a bit, the idle mixture is too lean. The same goes for cutting out when throttling up.
As aspeed said, open the idle mixture a little bit. If after running wide open for a time and bringing it back to idle causes the idle to 'hang' for a bit, the idle mixture is too lean. The same goes for cutting out when throttling up.