Thunder Tiger F-54S 4 stroke - where are the fuel adjusters?

[Jim Burton 1]

I have just finished installing a new TT 4 stroke to replace my old OS 2 stroke in my Ready 2. It's a snug fit, but I'm happy with access to the needle valve, helped by a metal rod extension.

 

So, time to break in the new engine, and I read the instructions with a mounting sense of confusion. It refers to adjustments of things I cannot identify, let alone get to: the only obvious adjuster being the usual ratcheted needle valve that I mentioned. But where is the 'choke valve' that I have to first close to prime the engine with fuel, and then re-open?

 

The needle valve I have mentioned turns out to be the 'high speed needle valve' which has to be opened to 2-2 1/2 turns to give a rich break-in mixture. That much is clear, but then the instructions continue with four paragraphs concerning the 'low speed needle valve'. This (to me) invisible item is 'located inside the throttle barrel' on the 'right hand side' of the carb viewed from the front. Is it indeed? A picture would be nice, TT guys.

 

I know I'm missing some things I should have located before installing the engine, but it has taken me a very fiddly week to get it snugly installed, and I am loath to take it all out again if, by seeking your help, I can be pointed to the location of these two adjusters so that I can drill access holes in the fuselage: there's certainly not enough room to get fingers in there!. I'm assuming these two items appear to be invisible to me because they are just tiny holes in the engine casing into which allen keys should be inserted and turned.

[John Tee]

Hi Jim.

 

I'm not familiar with TT 4st's but on my Saito there is a sliding plate in the air intake of the carby to act as a choke.I find I don't need it to start using an electric starter. Some makers have remove these but not amended the instructions.The low running jet is usually a small screw inside the throttle arm(on the opposite side to themain needle valve) with only a slot showing but it varies with the carby/make. This shouldn't need adjusting until the motor is nearly run in. Hope this helps and I'm sure thre will be someone with more knowhow than me along soon.

 

John

 

[Lee Smalley]

T T engines have both needle valves on the same side the low end needle is just below the main needle and is turned using a normal slotted screwdriver this is normally set very well already so do not touch it unless you really have to the carb does not have a choke ( well my tt130 does not) nor does it need one

[Jim Burton 1]

Thanks guys,

 

 

So these printed instructions are just out-of-date/generic/nothing-to-worry about, y'reckon?

 

In other words, all the break-in and subsequent mixture tweaks can be handled with just the needle valve. So, no choke and if there is a low speed needle, it will already be set perfectly well.

 

In the absence of any contrary input from a TT54S owner, I'll go with your advice. Can't tweak what I can't see, after all.

[David Davis]

Jim, I own a TT54 and would recommend them to anyone. Just run in the engine carefully and leave the slow-running needle alone unless the engine just won't run at slow speed.

 

You may find, and this applies to any engine, that it will not run perfectly until it has had a few hours running time but it is usually ok to run in the engine in the air once it's had a few tankfuls of fuel through it.

[oldSmithy]

This is the TT54 parts cat showing the choke assm "41" and the carb with the two adjusters "40A"

 

Hope this helps

 

[Jim Burton 1]

oldSmithy, may I thank for your time in retrieving the exploded diagram of the TT54: this corresponds almost exactly with the diagrams printed in my TT54S instructions sheet.

 

On mine, 40 and 41 are printed identically to yours, but instead of 40a, there is an exploded parts diagram of the individual carb bits.

 

Here's the puzzler: on both your diag and mine, assembly 41 (choke valve assembly) is shown as a knurled rotater (with allen key or bent metal arm) pointing out in the same direction as the needle valve, but just 'in front' of it. This certainly is not present on my hardware,

However, on closer inspection of the printed parts list, the item 41 'choke valve assembly' is listed separately under the heading 'Option Parts List'. Hmm. So I've been looking for an 'optional extra' which is not present. Perhaps in the 'TT54S' designation, as opposed to 'TT54', the 'S' stands for 'Several bits missing'!

 

The reassuring posts from all are appreciated: I'm going ahead with the run-in, and the slow running adjustment will have to look out for itself

 

Thanks to all.

[GONZO]

IIRC the TT54 I once owned had the carb type as shown in pic 40a, this is an air bleed carb. The low speed mixture adjustment, such as it is, is achieved by adjusting the amount of air(not fuel) bled into the partially closed throttle. In pic 40a you can see a small horizontal boss, the width of the carb, facing towards you. In the middle of this is a small hole which conects to the carb inlet. The amount of air allowed through this hole is controlled by the small screw sticking out on the left - screw in to richen (less air as the hole is blocked more), screw out to weaken. Best start with the screw end half way across the hole. This is the opposite way if you have a later carb that does indeed have a low speed fuel metering needle. More details if required.

HTH

Edited By GONZO on 25/08/2011 17:27:51

Edited By GONZO on 25/08/2011 17:28:27

[Jim Burton 1]

I've finally 'run to earth' the reason for the apparent contradictions in several of the descriptive posts above.

 

The TT website gives details of the TT54 as you would expect, but shows that there have been THREE different models - the 9800 original with 'choke valve' arrangement as shown in oldSmithy's post above; the 9801 also with a choke valve, but its size and complexity much reduced. Finally the current model 9803 (my one) with no choke valve at all.

Both the carbs for the 9800 and 9801 have different sticking-out extra needle valve adjusters, doubtless for slow running adjustment. I attach a photo of the current carb on my model 9803 which you can see has now been refined to a 'no choke' system with no sticking out slow needle valve.

As some of you have stated above, in your experience there is no need for a choke, and it looks like TT agree. It also looks like the slow running valve is a set-it-and-forget-it job, with just the end of a screw head visible.

 

Careless of the confusion this has caused, TT supply the instruction leaflet for the 9800 with the current 9803. This despite the fact that a perfectly good up-to-date pdf file for the 9803 is downloadable from the website. All mention of the 'choke valve' has now been removed from the starting procedure (see attached screen shot).

Grrr.

[GONZO]

No that screw is the throttle barrel retention screw. The inner end locates in a helical slot in the carb barrel such that as you opperate the throtle lever the barrel rotates and also moves in and out. This does not appear to be an air bleed carb. The slow running needle will be located recessed in the centre of the throttle lever/barrel. Turn by 1/8 turn at a time; in to weaken the low speed mixture and out to richen.

HTH

[Jim Burton 1]

OK, thanks for straightening that out for me - screw in the centre of the throttle lever/ barrel, not the one I arrowed.

 

cheers.

[ken anderson.]

hello JB....... i think you'll find the slow running adjustment is the opp side to the main needle(the large adjustable one in the photo)....you say your engine is new-- i would start it up ... put a couple of tanks of fuel through before you start adjusting the low speed end.......... give it time to settle in etc.....and you'll prob find it'll only need a minor amount of out/in ..... to give it a smooth transition to high rev's ....

 

 

ken anderson ne...1 ... 4st dept.

[Jim Burton 1]

Thanks Ken, and all who offered help: I'm going to have to remove the engine and rig up a bench run. With the engine installed in the plane, it's such a snug fit that I can't get to see - let alone adjust - all the various suggested locations for the slo-valve.

 

For future forum searchers, I'll take some close-up photos 360deg around the engine and carb, and label the position of the adjuster(s).

 

Cheers all.

[Peter Witherington]

I have read this chain with interest being on my third TT54 4s. I have never had any problem with he carberettor of idling adjustment. my problem has been with part 24 in the parts list - the spring hold collars. On each of my engines these collars have shattered. I have replaced them (£5 per pair) but they have shattered again. With the first engine I eventually replaced the valves, valvel springs, the spring retainer sets and hold collars but the result was teh same. I therefore decided to replace the engine and spent a great deal of careful time running it in accordance with the instructions but withing a month the engine went pop in the air (fortunately I safely got the model back down) but this time I resisted the temptation to take the rocker cover off and look. I took the engine back to the model shop - showing its near pristine condtion and between them and TT they decided to replace it. Since the symptoms were identical (the engine going pop under full power and then total loss of compression) I am certain that is was the collars again. However the message back from TT was they did not know what the problem was and they therefore replaced it.

I returned home once again a happy man an carefull re-installed the gleaming new engine. First off was to run it in - again great care, best 4s 20% oil fuel, low revs, making sure the mixture was rich (so much so that I had to keep the glow lead on). A total of 45 minutes running - then off to the flying field and first flight was fantastic (apart from pilot effor landing which removed the undercarriage. Back home replace undercarriage and a week later back to the field. 3rd flight - pop successful but dodgy landing and yes off course no compression. this time I did take the rocker cover off and yes once again there are pieces of shatterd collar. Only the inlet valve had gone completely but the exhaust valve collar came out in two seperate bits. Before I take the engine back to the model shop again has anyone else experienced anything like this and got any ideas if I am doing anything wrong.

[Jim Burton 1]

That's a real horror story, Peter. You seem to have done everything correctly in the running-in revs and fuel choice. I hope expert advice will be forthcoming from this forum.

 

Back on thread topic, here's the photo showing (finally!) the correct location of the slow mixture adjuster on this latest version 9803 engine.

[Steve Hargreaves - Moderator]

@Peter I think you are doing the right thing...if a new motor fails it should be returned to the supplier. So many collet failures must point to a quality control problem at the factory IMHO...either the wrong material or incorrect hardening or out of tolerance would seem the most likely.

 

The only other possibilities could be a lack of tappet clearance or serious over-reving of the engine....

 

After so many failures I think I would be tempted to ask for a refund & try another make......worth noting that the ASP61 four stroke is effectively a "big bore" version of the 52 so uses the same crank case/mountings as the 52. I have one & its a great motor....spins a 12x6 very nicely....

[ken anderson.]

JB-thats your screw...... as i said previous only a 1/4 turn at a time(if that)...make a note of where it is before you start......and finally make sure the engine is warmed up before altering any settings.....

 

 

ken anderson ne...1 .... 4st dept.