I am having a bit of a problem getting my ST 51 to run smoothly. I have had STs before so I know you have a delicate balance between the low end and high end before you get it just right. I recall reading somewhere that the position of the spray bar is very critical as well. Has anyone also heard of this? And what position would be ideal? Most engines like it pointed straight down but I seem to think the STs prefer a little upward thrust of the spray so if you are looking from the needle valve side it would be pointed around 4 o'clock. Any thoughts or experience on this? Many thanks.
On Mon, 30 Jun 2008 15:57:41 -0700 (PDT), Ted <tkenned...@msn.com> wrote in <b975c373-fd62-4388-8d65-3ad1457d1...@w34g2000prm.googlegroups.com>:
>I am having a bit of a problem getting my ST 51 to run smoothly. I >have had STs before so I know you have a delicate balance between the >low end and high end before you get it just right. I recall reading >somewhere that the position of the spray bar is very critical as well. >Has anyone also heard of this? And what position would be ideal? Most >engines like it pointed straight down but I seem to think the STs >prefer a little upward thrust of the spray so if you are looking from >the needle valve side it would be pointed around 4 o'clock. Any >thoughts or experience on this? Many thanks.
I have no personal experience of tuning an ST.
Their web site (and many other people who have posted here since 1995) recommends that the hole in the spraybar be straight down:
As often happens with tuning, people disagree about what works and what doesn't work. In my view, you should feel free to experiment and report your results here so that the peanut gallery can learn from your mistakes. :o)
Marty -- Big-8 newsgroups: humanities.*, misc.*, news.*, rec.*, sci.*, soc.*, talk.* See http://www.big-8.org for info on how to add or remove newsgroups.
On Jun 30, 6:57 pm, Ted <tkenned...@msn.com> wrote:
> I am having a bit of a problem getting my ST 51 to run smoothly. I > have had STs before so I know you have a delicate balance between the > low end and high end before you get it just right. I recall reading > somewhere that the position of the spray bar is very critical as well. > Has anyone also heard of this? And what position would be ideal? Most > engines like it pointed straight down but I seem to think the STs > prefer a little upward thrust of the spray so if you are looking from > the needle valve side it would be pointed around 4 o'clock. Any > thoughts or experience on this? Many thanks.
> Ted
Start with the spray bar straight. It may take a tiny twist later but that is usually your last resort. The most important thing you can do, in particular with the ST51, is switch to an OS-8 glow plug. The ST plugs are basically junk. I fought with my ST51 for months before I came to that simple solution. It simply wouldn't mid-range well. Now it runs great, hardly ever needs adjustment, and starts easily.
>I am having a bit of a problem getting my ST 51 to run smoothly. I > have had STs before so I know you have a delicate balance between the > low end and high end before you get it just right. I recall reading > somewhere that the position of the spray bar is very critical as well. > Has anyone also heard of this? And what position would be ideal? Most > engines like it pointed straight down but I seem to think the STs > prefer a little upward thrust of the spray so if you are looking from > the needle valve side it would be pointed around 4 o'clock. Any > thoughts or experience on this? Many thanks.
> Ted
A couple of weekends ago we took apart a ST45 carb. Seems to me(<-that was a disclosure about accuracy), the spray bar was at 4 or 5 o;clock when viewing it from the needle end. It looked to be pointing right down the throat of the engine. I have one I could go take apart and look at if ya want? Use an OS #8 mk
>I am having a bit of a problem getting my ST 51 to run smoothly. I > have had STs before so I know you have a delicate balance between the > low end and high end before you get it just right. I recall reading > somewhere that the position of the spray bar is very critical as well. > Has anyone also heard of this? And what position would be ideal? Most > engines like it pointed straight down but I seem to think the STs > prefer a little upward thrust of the spray so if you are looking from > the needle valve side it would be pointed around 4 o'clock. Any > thoughts or experience on this? Many thanks.
> Ted
The spray bar position is considered to be a tuning adjustment also. In my club we would swap the ST carb for an OS. Then they would run like a raped ape.
>I am having a bit of a problem getting my ST 51 to run smoothly. I > have had STs before so I know you have a delicate balance between the > low end and high end before you get it just right. I recall reading > somewhere that the position of the spray bar is very critical as well. > Has anyone also heard of this? And what position would be ideal? Most > engines like it pointed straight down but I seem to think the STs > prefer a little upward thrust of the spray so if you are looking from > the needle valve side it would be pointed around 4 o'clock. Any > thoughts or experience on this? Many thanks.
Is it a true 2 needle carb, and not a high speed needle and air bleed valve?
If the spray bar changes do not do the trick, and it is a two needle carb, you might be able to take a trick from the older Fox engines.
The instructions told the user to modify the profile of the low speed needle to adjust the midrange.
The told you (and they were right) to chuck it into a drill, and turn it fast, and put some sandpaper to it, either on the tip to "dull it" or the "shoulder" where the angle met the full diameter of the shaft.
I think (it has been a while) if the midrange was lean, you sand a small radius on the shoulder. It does not take much, and if you go too far, be prepared to buy a new needle and try again. DAMHIKT! <g> -- Jim in NC
> On Mon, 30 Jun 2008 15:57:41 -0700 (PDT), Ted <tkenned...@msn.com> wrote > in > <b975c373-fd62-4388-8d65-3ad1457d1...@w34g2000prm.googlegroups.com>:
>>I am having a bit of a problem getting my ST 51 to run smoothly. I >>have had STs before so I know you have a delicate balance between the >>low end and high end before you get it just right. I recall reading >>somewhere that the position of the spray bar is very critical as well. >>Has anyone also heard of this? And what position would be ideal? Most >>engines like it pointed straight down but I seem to think the STs >>prefer a little upward thrust of the spray so if you are looking from >>the needle valve side it would be pointed around 4 o'clock. Any >>thoughts or experience on this? Many thanks.
> I have no personal experience of tuning an ST.
> Their web site (and many other people who have > posted here since 1995) recommends that the > hole in the spraybar be straight down:
> As often happens with tuning, people disagree > about what works and what doesn't work. In > my view, you should feel free to experiment > and report your results here so that the peanut > gallery can learn from your mistakes. :o)
> Marty > -- > Big-8 newsgroups: humanities.*, misc.*, news.*, rec.*, sci.*, soc.*, > talk.* > See http://www.big-8.org for info on how to add or remove newsgroups.
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Many folks, because of previous exposure to OS "no break-in" engines, attempt to fine tune and fly a Super Tigre engine long before it is ready to be put into service. These are the folks that end up complaining about those miserable ST carburetors.
Marketing will not mention just how long an ST engine needs to be broken-in because of a possible loss of sales, so they let their customers bumble around making confetti of their models because of an improper break-in regime. All marketing cares about is profit. Not their customers' well being or enjoyment of their purchase.
Super Tigre engines are fine engines, but none of them come ready to fly right out of the box, like OS. Trying to break-in an ST engine in the air, unless it is ABC, is pretty much a waste of time and nearly a sure bet to destroy your model, unless you are very experienced and are accustomed to deadsticks and their requisite landings.
This does not make ST engines a bad buy. It simply means that one has to learn something new and employ a test stand for break-in. Once accomplished, an ST engine will last many decades of fairly rigorous use. Not done properly, the engine can be ruined in no time flat.
Once the engine is broken-in, the carb that comes with ST engines suddenly changes into a pussycat to adjust and operate. Surprise!
>Many folks, because of previous exposure to OS "no break-in" engines, >attempt to fine tune and fly a Super Tigre engine long before it is ready to >be put into service. These are the folks that end up complaining about those >miserable ST carburetors.
>Marketing will not mention just how long an ST engine needs to be broken-in >because of a possible loss of sales, so they let their customers bumble >around making confetti of their models because of an improper break-in >regime. All marketing cares about is profit. Not their customers' well being >or enjoyment of their purchase.
>Super Tigre engines are fine engines, but none of them come ready to fly >right out of the box, like OS. Trying to break-in an ST engine in the air, >unless it is ABC, is pretty much a waste of time and nearly a sure bet to >destroy your model, unless you are very experienced and are accustomed to >deadsticks and their requisite landings.
>This does not make ST engines a bad buy. It simply means that one has to >learn something new and employ a test stand for break-in. Once accomplished, >an ST engine will last many decades of fairly rigorous use. Not done >properly, the engine can be ruined in no time flat.
>Once the engine is broken-in, the carb that comes with ST engines suddenly >changes into a pussycat to adjust and operate. Surprise!
>Ed Cregger
Ed:
In your estimation, Does this apply equally to the new oriental ST engines as to the older ones Italian manufacture?
>>Many folks, because of previous exposure to OS "no break-in" engines, >>attempt to fine tune and fly a Super Tigre engine long before it is ready >>to >>be put into service. These are the folks that end up complaining about >>those >>miserable ST carburetors.
>>Marketing will not mention just how long an ST engine needs to be >>broken-in >>because of a possible loss of sales, so they let their customers bumble >>around making confetti of their models because of an improper break-in >>regime. All marketing cares about is profit. Not their customers' well >>being >>or enjoyment of their purchase.
>>Super Tigre engines are fine engines, but none of them come ready to fly >>right out of the box, like OS. Trying to break-in an ST engine in the air, >>unless it is ABC, is pretty much a waste of time and nearly a sure bet to >>destroy your model, unless you are very experienced and are accustomed to >>deadsticks and their requisite landings.
>>This does not make ST engines a bad buy. It simply means that one has to >>learn something new and employ a test stand for break-in. Once >>accomplished, >>an ST engine will last many decades of fairly rigorous use. Not done >>properly, the engine can be ruined in no time flat.
>>Once the engine is broken-in, the carb that comes with ST engines suddenly >>changes into a pussycat to adjust and operate. Surprise!
>>Ed Cregger
> Ed:
> In your estimation, > Does this apply equally to the new oriental ST engines as to the older > ones > Italian manufacture?
> bob
I'm not Ed but I concur with what he said and I have a newer ST45 and it took some breaking in and now is much better. mk
>>Many folks, because of previous exposure to OS "no break-in" engines, >>attempt to fine tune and fly a Super Tigre engine long before it is ready >>to >>be put into service. These are the folks that end up complaining about >>those >>miserable ST carburetors.
>>Marketing will not mention just how long an ST engine needs to be >>broken-in >>because of a possible loss of sales, so they let their customers bumble >>around making confetti of their models because of an improper break-in >>regime. All marketing cares about is profit. Not their customers' well >>being >>or enjoyment of their purchase.
>>Super Tigre engines are fine engines, but none of them come ready to fly >>right out of the box, like OS. Trying to break-in an ST engine in the air, >>unless it is ABC, is pretty much a waste of time and nearly a sure bet to >>destroy your model, unless you are very experienced and are accustomed to >>deadsticks and their requisite landings.
>>This does not make ST engines a bad buy. It simply means that one has to >>learn something new and employ a test stand for break-in. Once >>accomplished, >>an ST engine will last many decades of fairly rigorous use. Not done >>properly, the engine can be ruined in no time flat.
>>Once the engine is broken-in, the carb that comes with ST engines suddenly >>changes into a pussycat to adjust and operate. Surprise!
>>Ed Cregger
> Ed:
> In your estimation, > Does this apply equally to the new oriental ST engines as to the older > ones > Italian manufacture?
> bob
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Bob, I suspect that the Chinese are making the engines a little better, or they have switched to softer metals, because I have heard that the newer Chinese engines take a little less time to come in on the average. I have no scientific proof of this at all. But lots of folks are reporting, via the web, that the engines, while not as readily broken-in as OS, are better in this respect than they were back in "the old days".
I'm not knocking Italy's Super Tigre's efforts either. CNC machinery hasn't been around all that long, so the Italians may not have been set up as well in this regard as the current Chinese manufacturers.
