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*** CLUB SUPER TIGRE ***

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Old 08-19-2012, 11:10 PM
  #1501
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Default RE: *** CLUB SUPER TIGRE ***

Lowering the nitro content or installing a colder plug can improve the midrange.
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Old 08-20-2012, 06:39 AM
  #1502
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I will try 5% nitro. I already am using a cool plug, Fox #8.
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Old 08-20-2012, 08:12 AM
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ORIGINAL: hsukaria

I will try 5% nitro. I already am using a cool plug, Fox #8.
You'll want a long reach hot plug for running 5% nitro. A mild plug will work but idle quality will probably suffer. I like McCoy MC59's myself.

Super Tigres don't like much nitro. 10% max.
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Old 08-20-2012, 08:58 AM
  #1504
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Default RE: *** CLUB SUPER TIGRE ***

What about 0% nitro, would that work? Anybody have experience with 0% on ST engines?
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Old 08-20-2012, 10:13 AM
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Default RE: *** CLUB SUPER TIGRE ***

Iuse Merlin Plugs myself, I often end up with a cold car plug like a 2006 in my airplane engines. they are long reach plugs of excellent quality and he has enough heat range selections to satisfy any need.
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Old 08-20-2012, 11:23 AM
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ORIGINAL: hsukaria

What about 0% nitro, would that work? Anybody have experience with 0% on ST engines?
It would work, but you'll lose power. I lose 800rpm going from 5% to 0% in my S90K. It has a snappier exhaust note on FAI fuel though. I added 3% acetone to my homebrew FAI fuel and it idled and transitioned good but top rpm was down.
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Old 08-20-2012, 11:55 AM
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Default RE: *** CLUB SUPER TIGRE ***

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ORIGINAL: hsukaria

I need advice tuning my ST G51. The past year or so I noticed that the midrange transition is very rich and I get a stumble, sometimes big surges (engine cuttng) while transitioning from idle to WOT while flying. It acts like it is very rich in the midrange. Sometime ago I loosened the 2 throttle barrel screws and rotated the throttle assembly very slightly clockwise to help lean it a bit. The low speed needle valve is set as lean as I can get it without sacrificing a good idle, the high speed needle is set just a bit rich from peak. So, should I rotate the throttle barrel clockwise some more?
I am running 15% nitro with a medium plug, 11x7 prop and a MACs one-piece muffler. Performance is excellent except for the throttle transition.

Thanks.
Ringed Tigers need to be adjusted to get the correct setting after they are broken in, so its normal for the carb to need readjusted as they go through breakin.
The original muffler has the correct back pressure for the engine it comes with. Aftermarket mufflers often are not designed for the particular engine they are advertised/sold for so they don't give the correct back pressure thus it's hard to get good fuel feed and transition/midrange.
15% seems like a high nitro percent for a tiger - try 10%.

Ed
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Old 08-25-2012, 05:09 AM
  #1508
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Default RE: *** CLUB SUPER TIGRE ***

Sorry I took so long to back to you on my G51 throttle transition being too rich and sluggish. I tried 5% nitro Cool Power fuel with a Fox #8 glow plug, 11x7 prop. The transition with 5% nitro was much better, it was a great improvement. I noticed that the engine might have a bit less power on the top end compared to 15% nitro, but the plane was already so overpowered (Escapade 40), that a slight drop in power wouldn't matter. Problem solved. Thanks for the help guys!!!
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Old 09-18-2012, 06:43 AM
  #1509
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I have a new ST project engine. A guy at the club gave me an old Italian G51 that just came out of a big crash. I took it home and cleaned it in a crock-pot with antifreeze. I corrected the carb jet orientation (cat-eye slot) to point straight down (was way off), installed the carb and muffler, and mounted it on my engine test stand. I put several drops of after-run oil in it since I didn't have a chance to start it right away. I immediately noticed that when I turn the engine over with the throttle closed all the way that after-run oil oozes and bubbles out of the carb base and the front bearing.
My questions are: Where would I find the correct o-ring seal for the carb? How bad is it that I leak oil out of the front bearing (I know a bit is ok, but this seems a lot considering I am slowly turning it by hand).

The compression is great, but the bearings feel a tiny bit scratchy, but not noticeable unless you are really listening (I got other engines that sound similar and are running fine).
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Old 09-18-2012, 12:20 PM
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Default RE: *** CLUB SUPER TIGRE ***

I just realized the G51 is still being made today. So the newer engines may have used a sealed front bearing. But the older earlier engines didn't have a sealed front bearing.
Normally oil oozing out of the front bearing isn't a problem as it means the bearing is getting well lubricated. But I don't know if the newer engines are using a sealed bearing or not now. But if the engine is running good and idles good, then having oil oozing out of the front bearing is not a problem. It may not be worth the effort to tear the engine down just to replace the bearings if the engine is running good.

For the O-ring on the base of the carb, I just use one that fits OK from a box of assorted size O-rings I have. The O-ring isn't anything special for that purpose.

As to how much oil leaks out the front or not, depends on the engine brand and design a lot. With the engine cold there may be more clearance than when it is hot and all the parts have heated up good. If you wanted to, you could put in a sheilded bearing with the inner sheild removed and leave just the outer sheild. But if the engine is running good and idling good, it probably isn't worth the effort to fix anything until the bearings need replacing.


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Old 09-18-2012, 03:52 PM
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Default RE: *** CLUB SUPER TIGRE ***

If the rotary intake valve system is well fitted it shouldnt leak too much while its running, Iuse fuel with plenty of lube to provide the extra seal needed there and with a good percentage of castor.
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Old 09-18-2012, 03:54 PM
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Default RE: *** CLUB SUPER TIGRE ***

If the rotary intake valve system is well fitted it shouldnt leak too much while its running, Iuse fuel with plenty of lube to provide the extra seal needed there and with a good percentage of castor.
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Old 09-19-2012, 03:58 AM
  #1513
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Default RE: *** CLUB SUPER TIGRE ***

Thanks, I have a few o-ring seals that I can try to match the right size for the base of the carb. That is the one I was more worried about. I can live with an oil leak from the bearing. I was just worried about excessive air leaks that bypass the carb needle assembly.
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Old 09-19-2012, 04:51 AM
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Quote:
ORIGINAL: hsukaria

Thanks, I have a few o-ring seals that I can try to match the right size for the base of the carb. That is the one I was more worried about. I can live with an oil leak from the bearing. I was just worried about excessive air leaks that bypass the carb needle assembly.
Just make sure your replacement o-ring is soft and supple yet, and squish the carb down as hard as you can by hand before tightening the cinch bolt down. If you question the front bearing leaking too much, or if you think you have an o-ring leak below the carb, try running the engine on a stand at low throttle settings and try shooting some brake cleaner using the straw at the base of the carb and near the front bearing. If there is an excessive leak, the engine will ingest the brake cleaner and the engine will stall immediately. This is a trick the car guys use to determine if the front bearing is leaking air in. Oil leaking out is a good thing, IMO. If it pukes oil while running, the bearing could be bad or the reclamation channel in the crankshaft (if present) may be dirty/plugged.

Against the advice of numerous other folks, I use RTV (copper or black) to seal the o-ring on the bottom of the carb. It doesnt snuff my glow plugs out like some thing it will do, and the carbs never leak.. That is, at the o-ring. My ST engines have the problem of fuel leaking past the threads of the NV. Fuel tubing on the needle doesnt fix this on my S29.
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Old 09-19-2012, 06:41 PM
  #1515
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Default RE: *** CLUB SUPER TIGRE ***

I bench tested my freebie project ST51 today. I ran 5% nitro with added castor oil, 11x6 prop. I did not try to fix what I thought might be airleaks under the carb. I started it, but it would not stay running without the glow starter at first. So, I replaced the old glow plug (with an idle bar) with a Fox Miracle plug. Running extra rich, it still idled well, and throttle transitions were fast and smooth. I did not see any fuel/oil leaking out of the front bearing or the carb base. I did hear a rattling sound and I sadly concluded that it is the bearings. However, after finishing the test runs, I noticed that the stock muffler was loose where it clamps to the header (very slightly loose). So, I am wondering if that is the cause of the rattling sound I was hearing. I now remember why my other 2 ST engines use MACs mufflers instead of the stock ST mufflers. I really don't like those stock ST mufflers, very heavy.

I will try to get a spray can of brake cleaner to check for leaks, re-install the carb with a newer o-ring seal, and a different muffler. I will also try to get a tach that works, mine broke. My plan is to run a 12.25x3.75 3-D prop on it. Do you guys think it can handle it?.
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Old 09-20-2012, 04:29 PM
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Default RE: *** CLUB SUPER TIGRE ***

I bench ran my project G51 again today. I put in a new o-ring under the carb, replaced the muffler with an old OS muffler, put on a big APC 13x4 prop. With 5% nitro (with extra castor added), I was able to get 9000 rpm and idle below 2500 rpm, with excellent throttle response. The rpms might have been even higher because it was sunset and the tach might have missed a few revs. Also, I was not peaking the engine, it was running rich. So I am happy about the performance, I plan on installing it in a Seagull Harrier in place of an OS 70 Surpass.

But my problem that the engine occassionally rattles quite loudly, but not always. I gripped the muffler to make sure it wasn't the muffler coming loose, and it wasn't. So does this mean that one or both of the bearings are bad? I don't feel or hear anything from the bearings when I am turning it by hand.

Thanks in advance for any help.
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Old 09-20-2012, 06:08 PM
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Default RE: *** CLUB SUPER TIGRE ***

Check the conrod bushings, and if it's ringed check the ring groove.

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Old 09-20-2012, 06:37 PM
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ORIGINAL: 1QwkSport2.5r

Check the conrod bushings, and if it's ringed check the ring groove.

Well, both are areas that I never dealt with.

If the conrod bushings are bad, do I just replace the whole conrod?

If the ring groove is bad, do I replace the whole piston (and ring)?

Can I just continue to run it as is until it finally breaks?

Sorry about all these questions, this is a whole new area for me.

If these are definitely the trouble areas, I would only need to replace the piston, ring, and conrod. I don't imagine that the cylinder liner is bad since I am getting very good compression. I think a whole teardown analysis is in order.
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Old 09-20-2012, 07:01 PM
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Default RE: *** CLUB SUPER TIGRE ***

At the very least, pull the piston and conrod out and inspect carefully. Perhaps, remove the backplate first and rotate the engine watching the big end of the conrod. There should be some play in the bushing, but not a lot. Next check the wristpin and small end of the conrod. If there is noticeable play, replacement is not a bad idea. If the ring groove is noticeably wider than the ring, replace the piston. A Frank Bowman ring will round out the rebuild, even if all of the above checks out o.k. No sense using an old ring, especially when Bowman rings are so much better.

IMHO, don't run it til it breaks. Fix it right beforehand and the engine will last a long long time. With it tore down that far, I would replace the bearings even if they seem okay. Better safe than sorry.

This is what I would do if it were mine.
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Old 09-20-2012, 08:53 PM
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Default RE: *** CLUB SUPER TIGRE ***

Good luck finding a rod, Ineed one for my 40.
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Old 09-21-2012, 02:39 AM
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ORIGINAL: jeffie8696

Good luck finding a rod, I need one for my 40.
I was told the same thing for pistons for my s29 and s90, but I see them on *bay all the time. There are lots of parts out there, just have to look and be patient.
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Old 09-21-2012, 05:13 AM
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I checked out the parts prices at Tower Hobbies. It would be worth it if only one part needed rep;acement, but if I add up all the parts we are talking here, it would cost as much as a new engine. So, I will shop around for a used parts engine. Thanks.
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Old 09-21-2012, 07:09 AM
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Default RE: *** CLUB SUPER TIGRE ***

Got a couple of engines in a trade a ringed .40 and a non ringed .45. The .45 does to look broken in so I just let it be. The .40 is turning 13,700 on a MA 10x6 with 10% nitro. Is this about right or should I prop it up a little?

Andy
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Old 09-21-2012, 08:05 AM
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Quote:
ORIGINAL: AJsToyz

Got a couple of engines in a trade a ringed .40 and a non ringed .45. The .45 does to look broken in so I just let it be. The .40 is turning 13,700 on a MA 10x6 with 10% nitro. Is this about right or should I prop it up a little?

Andy
It depends on what plane you will have it on. I have been running a G40 in a Quickie 500 plane with a small prop 9x7 or 8.75x8.75 revving up insane rpms and a G51 turning 13x4 at 9000+ rpms. If it were me, for a general sport plane, I would go up a size (11x5, 12x4 or similar).
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Old 09-21-2012, 08:23 AM
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Default RE: *** CLUB SUPER TIGRE ***


Quote:
ORIGINAL: hsukaria

I checked out the parts prices at Tower Hobbies. It would be worth it if only one part needed rep;acement, but if I add up all the parts we are talking here, it would cost as much as a new engine. So, I will shop around for a used parts engine. Thanks.
Before ordering any parts, I would find out what is wrong in the first place. It might be something simple and cheap.
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