Author Topic: super tigre g34 ringed problems. (Read 4121 times)

brian thomas bennett · « **on:** February 16, 2010, 04:12:46 PM »

Hi Guys, I have bought a super tigre g34 ringed for my twister but am having a few problems with it . The needle needs to be virtually shut off for it to run, if i back off the needle even slightly the motor shuts down, it will not idle at all. The engine will not run on muffler pressure either,to see what was going on i attached the muffler pressure pipe while the engine was running on the bench,the engine went sick straight away and stopped? I have tried changing the glowplug for a few different types but this hasn't helped. Does the hole in the spraybar need to point directly down to the crankshaft? The fuel draw is not very good when choking the carb is this normal? The reason i tried changing the plug was because when i started the engine and removed the glowclip the engine would stop. If i turn the needle in to virtually peak power the engine does not stop when i remove the glo clip? HELP!!! Regards Brian U.K

Allan Perret · « **Reply #1 on:** February 17, 2010, 07:01:35 AM »

Quote from: brian thomas bennett on February 16, 2010, 04:12:46 PM

Hi Guys, I have bought a super tigre g34 ringed for my twister but am having a few problems with it . The needle needs to be virtually shut off for it to run, if i back off the needle even slightly the motor shuts down, it will not idle at all. The engine will not run on muffler pressure either,to see what was going on i attached the muffler pressure pipe while the engine was running on the bench,the engine went sick straight away and stopped? I have tried changing the glowplug for a few different types but this hasn't helped. Does the hole in the spraybar need to point directly down to the crankshaft? The fuel draw is not very good when choking the carb is this normal? The reason i tried changing the plug was because when i started the engine and removed the glowclip the engine would stop. If i turn the needle in to virtually peak power the engine does not stop when i remove the glo clip? HELP!!! Regards Brian U.K

Is this a c/l version or RC version ? (Not understanding what you mean by "it will not idle at all"). Why would you be trying to get it to idle ?
If it is a c/l engine, the problem you described sounds to me like you have a problem with the NVA, no control of fuel flow, either full flow or none..

rustler · « **Reply #2 on:** February 17, 2010, 01:55:17 PM »

Our club has not had much luck with these motors for stunt, even after applying the traditional "stunt mods". Aren't they basically a helicopter motor, and excellent engines for that purpose?

dennis lipsett · « **Reply #3 on:** February 18, 2010, 10:46:39 AM »

Quote from: rustler on February 17, 2010, 01:55:17 PM

Our club has not had much luck with these motors for stunt, even after applying the traditional "stunt mods". Aren't they basically a helicopter motor, and excellent engines for that purpose?

Ian,
the ST34H was the ABC version and it is far superior to the ringed version. Was a nice engine for carrier and helis. Sadly not made anymore since they moved to China. Great Plains won't spend any money on ABC stuff. Not as profitable as a simple ringed version.
dennis

edit. Also most 30 size helis don't use small 30 sized engines anymore. TT36 and 39 OS37 were the engines of choice a few years ago. Don't even know if anyone flies a 30 anymore.

Alan Hahn · « **Reply #4 on:** February 18, 2010, 12:15:18 PM »

Quote from: dennis lipsett on February 18, 2010, 10:46:39 AM

Ian,
the ST34H was the ABC version and it is far superior to the ringed version. Was a nice engine for carrier and helis. Sadly not made anymore since they moved to China. Great Plains won't spend any money on ABC stuff. Not as profitable as a simple ringed version.
dennis

edit. Also most 30 size helis don't use small 30 sized engines anymore. TT36 and 39 OS37 were the engines of choice a few years ago. Don't even know if anyone flies a 30 anymore.

I think the 36's and sub 40's are very similar in size and weight to the old 32's. So given a bigger displacement at almost no cost in weight or cash, most guys went for the bigger engine. For heli's every watt (or hp) counts!

As I recall a lot of the old 30 heli's even started with 28 size engines.

Getting back on topic, I know Fred Krueger modified a ST34 for stunt. I think it still needs some work. Maybe we can get him to post a comment or two.

fred krueger · « **Reply #5 on:** February 18, 2010, 01:38:01 PM »

It's been a couple years since I messed with that engine. As I recall, it was uncontrollable stock, so I blocked the boost and played with the compression. It subsequently ran OK in a profile, but used a lot of fuel. I also ran it in an ARF Nobler but it had severe inside/outside maneuver run changes. It was my impression that the venturi opening is excessively large which would account for the fuel consumption and the run changes. I do have plans to cut a new venturi (sprinkler type), using Claus Maikis numbers, and do some more tests. Maybe this Summer. I'll post any results.

Fred

brian thomas bennett · « **Reply #6 on:** February 18, 2010, 03:32:39 PM »

I have a sprinkler type venturi for the super tigre with OS type needle. I will try it on this set up as the venturi and needle supplied with the engine, as mentioned in my previous post gives no control at all.

fred krueger · « **Reply #7 on:** February 18, 2010, 05:22:22 PM »

Check Claus Maikis website for good starting dimensions for venturis:
http://www.clacro.de/
Click on 'Design', then 'Venturis'.

The engine may be responding in the manner you describe because it cannot draw fuel adequately through a too large venturi. Try muffler pressure with the existing venturi and the engine be happier.

Fred

RandySmith · « **Reply #8 on:** February 18, 2010, 05:56:27 PM »

I have setup many of these for people and I make lite Tube and tongues that work very well with them
The proper sized hole for a True venturie is a number 18 drill bit, this equates to about a 265 restrictor

It sounds to me like you have a combo problem of too large of a restrictor and a bad spray bar or a needle that is bent at the tip, or has the orifice hole inside the bar broken out

Regards
Randy

fred krueger · « **Reply #9 on:** February 19, 2010, 06:33:32 AM »

I just checked the stock venturi on mine. It measures 0.287" dia. That yields an effective cross-section of 14.1 sq. mm. That is right in the middle of Claus' recommended starting sizes for a .60!

Randy's setups are working well with a .265" so that would be a good starting point for you. Or, send the engine to Randy and have him set it up, including muffler. Follow his recommendations on plug, fuel, prop etc. and that should eliminate many potential problems.

Brian, I just reread your initial posting. You stated "The engine will not run on muffler pressure either,to see what was going on i attached the muffler pressure pipe while the engine was running on the bench,the engine went sick straight away and stopped?".
That makes complete sense. By connecting the pressure line while running, the fuel flow increased and the mixture went rich instantly, flooding the engine. When running muffler pressure the needle must be turned in (CW) further than the setting for suction draw.

Fred

brian thomas bennett · « **Reply #10 on:** February 19, 2010, 02:21:50 PM »

Hi Fred and Randy,Some news, I have had another good look at the spray bar and needle. I stripped it out of the venturi and had a good look at it under my magnifier. I looked through the spraybar under light and saw that there was something partially blocking it. I blew out the spraybar into a rag and a small piece of brass came out.

The needle seems fine no bends or other damage. I reinstalled the spraybar into the venturi and tried the engine. It ran much better the needle settings are now correct with much more scope for adjustment. The engine would still not run under pressure from the muffler though. Also still poor suction when choking the motor for prime,although it draws ok when running. I do have a jen venturi with sprinkler type needle setup from just engines. These are supposed to be manufactured from your PAMPA charts in the USA. I will check the measurements of the one i have and see if its suitable. Thanks for your help. Regards Brian.

Brett Buck · « **Reply #11 on:** February 19, 2010, 08:12:00 PM »

Quote from: brian thomas bennett on February 19, 2010, 02:21:50 PM

I do have a jen venturi with sprinkler type needle setup from just engines. These are supposed to be manufactured from your PAMPA charts in the USA.

I am not aware of anything resembling a "PAMPA Chart" for venturi size. Several people have come up with such things and they sort of work, to first approximation, but I don't think there is anything like that as an official PAMPA product or recommendation. The reason is that you can't a priori determine what venturi works on what engine. For example, my buddies and I are all running close to the same choke area engines from a 20FP to a PA75. It's certainly not proportional to the displacement.

Brett

Air Ministry . · « **Reply #12 on:** February 25, 2010, 07:35:25 PM »

sounds like the fuel may be 'off' too . . . ?

phil c · « **Reply #13 on:** March 01, 2010, 01:52:08 PM »

Quote from: brian thomas bennett on February 19, 2010, 02:21:50 PM

......The engine would still not run under pressure from the muffler though. Also still poor suction when choking the motor for prime,although it draws ok when running. Regards Brian.

Something else is still funny if it won't run with muffler pressure. It should run exactly the same, at least on the ground, just with a leaner needle valve setting to compensate for the extra pressure on the fuel. Prop size? Plug? Fuel? Will the motor track the needle valve smoothly, going from rich to lean and back again repeatably? Too much prop for the compression ratio and best rpm will tend to make the motor hard to set. Too little prop will make it run rough in the air.

Robin_Holden · « **Reply #14 on:** March 02, 2010, 11:02:15 AM »

Brian , hello from France.
Can I throw in my two penny's worth please ?

I have three G34's , all C/L motors and not 'converted' R/C ones. One is an old Italian manufacture and the other two are the later Chinese production.

All have the factory fitted venturi and NVA's. I have though fitted TWO Head Shims to each engine.
All perform in the same manner.

I use APC 10.5 X 4.5 Props' , fuel with a mix of around 17% synthetic / 6% castor.[5% nitro] .
They perform with around 3 and a half turns open on the needle.
I use Tongue Mufflers but NO muffler pressure.

Tanks for flying are Uniflow.

They can sometimes be very cantankerous when first getting started in a model at the field ! Typical Italian woman [ I'm British but a quarter Italian ! ] so I sometimes have to use an electric starter but not often.

After they were run - in , each would hold a nice 9,500 on the bench. Running - in was a pretty long process before they gave of their best.

That's about all , hope this helps you a bit.

Regards ,

Robin.

Robin_Holden · « **Reply #15 on:** March 02, 2010, 11:04:48 AM »

Brian , it's Robin again.

Forgot to mention that I always use the 'hottest' plug available. Enya No. 3 or similar.

Hope this helps you ,

Robin.

fred krueger · « **Reply #16 on:** March 15, 2010, 05:42:20 AM »

Here's a short video describing the modifications to my ST34 and a couple bench runs with 10.5x4.5 APC and a 10.5x5 Bolly Clubman props. The fuel used was home brew consisting of 5% nitro, 10% castor, 10% Klotz synthetic and the rest methanol with a touch of Armor-all for anti-foaming. Plug was a 2004 Merlin.
These are just my experimental attempts at making the engine run more 'stunt friendly'. I'm sure there are other opinions and methods and my suggestion is to do what works for you.
I will post results of 'in air' testing as soon as the Chicago area weather cooperates.

Fred

p.s.
I'm having some problems using the YouTube linking feature, so here's the URL:

afml · « **Reply #17 on:** March 15, 2010, 06:46:54 AM »

Many thanks for the informative video Fred!

Your results from the modifications were impressive.
Hope the weather soon becomes agreeable to test the results in actual flight conditions.

"Tight Lines!"

Wes

Author Topic: super tigre g34 ringed problems. (Read 4121 times)

brian thomas bennett

super tigre g34 ringed problems.

Allan Perret

Re: super tigre g34 ringed problems.

rustler

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dennis lipsett

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Alan Hahn

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fred krueger

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brian thomas bennett

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fred krueger

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RandySmith

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fred krueger

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brian thomas bennett

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Brett Buck

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Air Ministry .

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phil c

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Robin_Holden

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Robin_Holden

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fred krueger

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afml

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