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Violent Thunder Tiger

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Merco 6130/08/2017 15:42:39
54 forum posts
19 photos

I have been struggling to master a new Thunder Tiger 130 for about a week.I am pretty experienced with four strokes and most other aero engines but this one has me beaten. It is throwing props.I,ve tried all the usual fixes-plugs,emery washers,very rich needle settings,various fuels,but it keeps loosening the prop nuts with an alarming "crack".I have achieved a few runs but have been unable to get it to run burbling rich which is a worry-almost as if the main needle is too short.I,ve tried various GFP props between 15 and 18" and some wood,which are even worse..Sometimes I can get a very slow run with the throttle closed right down to a pinhole-almost oscillating-but even opening up using just a click on the throttle trim is enough to provoke a bang and a dive to avoid the flying prop.Have also tried reducing power to plug to reduce "over-advanced" syndrome. Please,can anyone release me from this tyranny?

ken anderson.30/08/2017 15:57:16
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8688 forum posts
808 photos

hello merco..sounds like the carb settings have been changed for the worse...if they have it may be better to start from scratch with them...... on all occasions I've seen 4/st's throw a prop its because they are too lean at the top end.....misses a beat and the prop is away.... be careful with it...powerful lump of metal...

ken Anderson...ne...1..... lump of metal dept.

Jon - Laser Engines30/08/2017 16:27:57
5513 forum posts
268 photos

Most strange behaviour.

I would suggest a 15x6 or 8 as a half decent run in prop, a 5% nitro fuel and an OS F plug.

What setup are you running?

Jon - Laser Engines30/08/2017 16:36:00
5513 forum posts
268 photos

Just had a thought

Make sure the woodruff key for the prop driver has not fallen out in the box. If it has the prop will slip almost the moment it fires and this could easily cause the problem. A friend had this with an OS52 and it took us ages to work it out!

Edited By Jon Harper - Laser Engines on 30/08/2017 16:36:11

Stevo30/08/2017 17:00:53
2699 forum posts
419 photos

Same here John - lost the woodfruff key... Props threw right across the garden... (I'm not stalking you this afternoon, honest)

graeme jones30/08/2017 17:39:02
277 forum posts
28 photos

Merco - I had exactly the same problem trying to run a Thunder Tiger 91 FS. I was hit twice by the prop, which came off as soon as the engine started, luckily without injury. Amerang said I was running it too lean, Model Technics said it was too rich. The supplied locking nuts are useless, they just come off with the prop, still locked together. I replaced them with OS locking nuts and did manage a few short flights, the engine stopping each time in the air because the prop had come loose, but been retained on the shaft by the OS nuts. In the end I gave up and bought an ASP 91 two stroke. Before anyone asks, yes I did use a very long spanner to tighten the prop nuts.

Graeme

cymaz30/08/2017 17:49:50
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9258 forum posts
1196 photos

I found a 16x6 ran well on them. If you dare take the back plate off and check the piston skirt. They are machined to within a thou of their lives. I had some missing on my 130. It ran very nicely once dialled in. i used only 5% nitro. also, try adding a head shim to cut the compression down a bit....and check the valves, againenlightened

ted hughes30/08/2017 18:27:56
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466 forum posts

I found this:**LINK**

Jon - Laser Engines30/08/2017 23:01:56
5513 forum posts
268 photos
Posted by cymaz on 30/08/2017 17:49:50:

I found a 16x6 ran well on them. If you dare take the back plate off and check the piston skirt. They are machined to within a thou of their lives. I had some missing on my 130. It ran very nicely once dialled in. i used only 5% nitro. also, try adding a head shim to cut the compression down a bit....and check the valves, againenlightened

in a former life at a model shop we had 3 tt130's that had to go back due to skirt failure. made a right old mess

Merco 6130/08/2017 23:12:43
54 forum posts
19 photos

Thanks very much for the response boys,some good and sound advice.To clarify my question,I,m using 5% with half and half synthetic/castor and OS F plug (new) Plug running from a separate batt via usual mosfet panel.16x6 Master broad blade. Starter from car batt. Woodruff firmly in place.The supplied lock nuts are useless,as you say,as there are only two or three threads on the internal coned outer nut.I,m using a substantial ring spanner on SC nuts but am not accustomed to having to use so much force-feels excessive and brutal.I like the idea of lowering compression,the comp on this engine is massive.A bit like trying to flick start a BSA Gold Star! I would not dream of hand starting this one. I,ve lost the settings on slow needle which is probably the problem.My method is to set main needle to full power,close barrel down onto a pin,connect a bit of fuel tube to carb inlet and blow,adjusting slow needle until I can just detect a hiss.Old as the hills but usually gives an approximate set up ready for fine adjustment.But it aint working on this engine.Cymaz,could you please tell me more about your mods to piston skirt,and what I should be looking for with back plate off.Finally,valve clearances are now spot on but did notice that there was no oil residue in rocker cover.Again,my sincere thanks to you all.

PS Re Nats.Am I the only one who wishes the sound of those lovely aero engines on the display line had not been drowned out by all those speakers pumping out loud musack and verbal irrelevance?

Jon - Laser Engines30/08/2017 23:27:11
5513 forum posts
268 photos

can you keep the prop on long enough to peak the main needle? it sounded like you are barely able to get the thing fired up at all.

if all else fails I'm happy to slap it on my test stand after work and see what we find

ted hughes31/08/2017 02:34:57
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466 forum posts

Am I right in thinking Thunder Tiger is a budget motor like Merco?

Buy cheap, buy twice.

Jon - Laser Engines31/08/2017 08:29:51
5513 forum posts
268 photos

TT sit almost on their own in between ASP below them and OS above. Their redline 53 heli engine was quite highly regarded if i recall and didnt suffer the bearing issues the OS 50 hyper did.

In general they were good for the price you paid. They certainly arent in the same class as MDS!

Engine Doctor31/08/2017 08:56:33
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2512 forum posts
39 photos

Hello merco . From you description It has all the symptoms of being over compressed. Do you have an exploded view /diagram of the engine. If you have check if there is a head gasket/shim if it should have one then I suggest you strip it and check that it's actually fitted. I have hard problems with fourstrokes over the years new and secondhand where the shim has either been left off for some reason or the owner has sworn they haven't stripped the engine but the him is missing.

To Chech if it is over compressed you could try fitting a short reach glow plug or add a couple of copper washers under your plug that effectively lowers the compression. Over compressing has the effect of advancing the timing causing the knock and prop throwing. If left you will either get hurt by the prop or the engine will be damaged ,possibly beyond economic repair.

E.D.

Edited By Engine Doctor on 31/08/2017 08:57:49

Denis Watkins31/08/2017 09:42:48
4459 forum posts
113 photos

**LINK**

This guy in the USA posts gaskets the same day to the UK at a total envelope, gasket and delivery cost around £5,

And they do fit and work

Jon - Laser Engines31/08/2017 09:51:53
5513 forum posts
268 photos

It would be a bodge but would be fine for an experiment. If you have a decent compass you could make a shim from kitchen foil.

Was the engine brand new? if so i would be surprised if there was a shim missing :\

ken anderson.31/08/2017 11:03:26
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8688 forum posts
808 photos
Posted by ken anderson. on 30/08/2017 15:57:16:

hello merco..sounds like the carb settings have been changed for the worse...if they have it may be better to start from scratch with them...... on all occasions I've seen 4/st's throw a prop its because they are too lean at the top end.....misses a beat and the prop is away.... be careful with it...powerful lump of metal...

ken Anderson...ne...1..... lump of metal dept.

it still sounds like the carb is upset?

ken Anderson...ne..1... check the carb dept.

Bobby31/08/2017 15:04:54
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88 forum posts
152 photos

Hi All, hope you do not mind me injecting this thread with a request, but my TT75F/S has again thrown it's crank bearings and I managed to find a supplier of bearings which are now duly fitted, I also modified the crankcase to insert a bleed nipple outlet at the bevel gear position and then blocked up the rear crankcase outlet cover to make sure the oil gets where it should, only to find the exhaust rocker arm adjusting cup bolt has damage inside, which in turn has also damaged the exhaust push rod surface. I do not know if the parts are subject to Nitride treatment during manufacture or just case hardened but without replacement parts my engine is naffed . having owned the 54fs,90fs and this one I am not a fan, but PEEPS. I would like to get this one back serviceable for my Bipe11. Having looked for several days for parts with no luck are they still in manufacture ??now Amerang seem to have gone Bobbysad

Jon - Laser Engines31/08/2017 15:10:12
5513 forum posts
268 photos

How bad is it Bobby? you might get away with it if you clean it up with some wet/dry.

i also think TT have stopped production of all engines now

Bobby31/08/2017 15:22:31
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88 forum posts
152 photos

Hi Jon, I'm afraid the damage to the cup part would require machine type work and re-hardening as I see it?, but the rod may clean up as you suggest. Not Hopeful then unless you/ others can suggest out/else. Regards Bobby indecision

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