DonStegall

My Feedback: (1)

I've got to get a SuperTigre GS-40 for some performance testing for Club 40 Racing

I haven't broken a ringed two stroke engine since the K&B Torpedo engines of the 70's.

I normally use Omega 15% with 4 ounces of castor added to bring it up to 20% oil. Will that do for this engine?

I use a PSP Mfg test stand for most all of my break-in operations and testing.

What is the best procedure for the first few minutes, and then the next half hour to hour of running time?

Jezmo

I don't add any castor to mine. I break them in on "As manufactured" Omega 15% running just lean of the break between two and four stroke for a full 8 oz tank. Then I fly it running 200 rpm's rich of peak. I also switch to Cool Power 15% with 2 oz of Castor added to each gallon after the first couple of tanks. It will continue to get stronger as the ring seats but more oil or rich running doesn't seem to help with that. Some seem to break in faster than others and I just always assumed the ring in those didn't get distorted as much when assembled at the factory. I have never had a rod big end problem doing it this way and I have run in at least 5 of them in the last couple of years as well as some of the older ones from Italy years ago. In my eyes it's the best bang for the buck around with the TT 40 Pro a very close second.

I just got my LA Racer and I will be comparing my ST GS40 with my TT 40 Pro on it. (Fixing to try some Club 40) Let us know how your tests go.

DonStegall

My Feedback: (1)

You'll have a blast with Club 40. The great thing is that the planes make fun everyday sport planes, and they do well on a pylon course as well. One thing I have found is that I really like to use some exponential on the control surfaces so that the plane is not twitchy. I have occaisionally forgotten to add it on a setup and the first flight is ... shall we say, entertaining.

What I'm up to is testing for the Novice/Bronze class. With the O.S. 40 LA apparently being discontinued, we need a good low cost solution for the entry level class. Chuck Waller had recommended that we try using the ST GS-40 with a larger diameter, low pitch prop like an APC 11x4 to keep the speed down. So I'm going to give that a try.

I think it may work because I've been testing a variety of engines on Club 40 planes. A lot of guys around here did not want to buy .40 engines. So I stuck a brand new, but broken in, O.S. .46 AX on a SRM2. With an APC 10x6 on it, it has a 5-10 mph advantage over the best TT Pro 40 I have. So I tried putting an AP 11x4 on the 46 AX and it brought it down to about the same speed as the TT Pro 40 planes prop'd for maximum speed. Some of the .46 guys around here have been using the APC 12.25x3.75 Stunt prop and you can actually torque roll a Sky Raider with that setup.

Hossfly

One thing about the current ST 40s that Great 'Panes' just refuses to correct is the absence of the carb. insert that came with the .40 engines when under World Engines, and was later installed in the Como series of engines which made them heads and shoulders more user-friendly than the ST from GP.

I am a ST fan since CL combat days back in '61 when the first ST 35s appeared. Talk about something to Break-In, wow that was a finger buster for the first couple hours.

That problem with the idle set-up makes the ST .40 a bummer among the rank and file RCer. All because of the idle problem. I make inserts out of brass tubing which work very well for those friends that want them. While one may lose 5-800 top end RPM with a sport prop, the increased reliability is almost unbelievable.

This engine should be the love of the Club 40 crowd if the rule-makers allow the insert, and the users can tolerate reliability over that last several hundred or so RPM.

I plan on finding out at the race at Scobee field on 9/29. Been a long time since I raced. Looking forward to a relaxed kind of racing.

fizzwater2

My Feedback: (61)

what insert are you referring to? I have an older GS40 ringed and don't remember any insert..

Jezmo

I have never had an insert in a GS40 either although I do remember them being in the Como's. Kinda makes me wonder if the Carb from a Coma got stuck on at the factory when the supply ran low on ST carbs. I have put the cut down spray bar from the larger 60-90 engines in the 40 and picked up some more power without any loss of idle reliability. I don't doubt that some GS40's have idle/transition issues but I have never owned one that did and after showing some of the guys at our field how to tune the ST carbs they absolutely love them. They really are good carbs, it just takes some know how to make them work. They are not very "newbie friendly" I guess is one way to put it.

Jezmo

At 49.95 it is a great entry level engine and since it is a ring motor they are virtually indestructable. Lean runs don't hurt them at all like they do with other types. They will outlast any bushing/ABN engine and that should be important for keeping the costs low. The one thing I don't like about the ST is the muffler. I would like to see them allow the Tower muff as it is only 15 bucks and doesn't add appreciably to the power. It does hold up much better than the stock one does and it is lighter which helps with model balance. (Mine all seem to come out nose heavy with that big ST muffler up there.) The most I gain switching from the stock ST to the Tower is about 100 rpm's. It adds much more to my other engines sometimes as much as 5 to 800 more r's but not on the GS40. I guess that ST muffler is sized for the GS40.

Taking some pitch out while adding diameter should slow them up a lot. Some experimenting like you are doing will show the correct relationship of pitch to dia. to get them back to where the LA's are now.

I haven't raced in many years but this seems like it will be a lot of fun. (At my age 428 would be more like work not fun) Have a great one and I hope your results are positive.

Hossfly

I don't even remember all the #s for the ST 40 engines. The ST 40 was around long before the Como came on the market, about '86 or so. Almost all those ST 40s I flew were round head, and I believe 6 head bolt models just like the Como engines when they appeared. The carbs were idntical so it mattered not whether ST or Como. Incidentally it was a Como I flew today as I still have another NIB Como 40 along with some Como .61s and a couple .90s NIB.
My inserted Como 40 using APC 10-5, racer, and buddie NJ with his TT 40 pro using 10-6 were just about neck and neck, although he may have been a tiny tad faster. I carry a big 1800 mah battery so I am a bit heavier.

Did you participate a few years ago when the 4-Star 40 racing thing was going here in the Houston area? Maybe you were tuning those "STOCK" ST 40s that were turning a 9-7 at 18,000 + RPM. Man those guys were some kind of "engine tuners"!
I also used those 60-90 spray bars until those "tuners" got that outlawed. However I didn't have to idle back then. [8D]

I will hand it to you, if you can ensure no spitting and sputtering on a ST 40 when going from idle to full throttle, all the time, you are definitely the man of the ST hour. 45 and 51 are no problem but the .40 gets me goat as every time I think I have it fixed, bam, it bites my butt. Hence the insert which solves all the problems.

Jezmo

All of my round head ST's were 45's. The 51's have given me the most problems although only the newest ones from China. I had an older one made in Italy that ran absolutely flawless. I read in somewhere another thread that all of the 51's now use the CL porting which explains why they turn 12X6 props so well. It's strange how the GS40's are giving you fits. After the the first tank I usually don't have to move the low needle nor the spray bar any more, only the high speed needle when changing fuel types/brands or if the weather changes significantly.

I didn't race when the four star stuff was popular but I did help some friends with their GS40's. I have always thought that for an inexpensive sport engine they were the best and most powerful. I like the saying, if it's ABx it is either wearing in and getting faster or it is wearing out.

On another note I work with a guy that I have been friends with for almost 20 yrs that goes by hossflyrick online. Yours is only the second time I have seen that used. Maybe I 'll see you at Scobie next weeend.

P.S. Your signature line is great. I wish more people understood and believed in that quote.

stanlattrell

I've been running ST engines and tuning their carbs since the late 60's and have found them to be more sensitive to tune on the low end due to the idle needle being so blunt. An eighth of a turn is a large adjustment, and may take you past the sweet spot. When close to right, moving the adjustment so you can just barely see the screw slot move is more in line with what it takes to get them right. The top end needle should be set at a rich 2-cycle first, and then do the adjustments on the low end, occasionally checking to see that the top end is still where it should be. I realize I may be giving advice to folks with more and better experience than I have -- another opinion may be helpful to someone having trouble........

The ringed engines need to have AT LEAST 5 tanks of 6 - 8 oz. each before you even try to set the low end -- the ring has to partially seat and the engine has to loosen up some before the low end will react right, allowing you to tell which way to adjust. As an aside, I have recently broken in and set the carbs on 2 ST GS 40's for Club 40 Racing, and I found the idle needle on BOTH these carbs were set more than a full turn rich as they came from the factory. For someone not familiar with ST carbs, this could really twist your tail..........

Another issue that can make them difficult to nearly impossible to tune correctly is an air leak around the carb throat -- if there is any question, use some sort of a sealer when installing and tightening the carb in the engine throat. This makes many problems go away...

Stan

DonStegall

My Feedback: (1)

Thanks to all for the information. I'm glad I posted requesting help before hand, as I'm sure the advice has saved me a lot of time. And I'm glad that you guys are willing to share. Thanks again.

stanlattrell

Don -- if the LA 40's are truly going away and we have to use something else for Club 40 Novice, I've had some thoughts that might be interesting to try...... What if the ST GS 40 was propped to match the LA 40 performance when using 10% (or 5%) fuel for the Novice Class, and then step the fuel to 15% maximum and open up the props to "anything is acceptable" to set up an Intermediate class?? The standing start, 10 lap times on this setup would be in the low to mid 1:40's at the fastest, and would be a strong step up from the Novice speeds of mid 1:50's at the fastest. Advanced Class could still be TT Pro 40 or GMS 40 engines with 15% fuel and any prop you choose for times in the mid 1:20's to low 1:30's for well-flown, really groovin' races. This would be another strong step up, and this scheme would provide more room for newer pilots to advance as their racing skills developed.

If this seems too complex, how about going directly to a TT Pro or GMS or ST 40 and set the nitro / prop combination to duplicate the current LA performance, and then step the fuel and open up the props to move into Advanced Class using the same engine / plane setup?
This would seem to me to keep the costs down as skills progress and pilots want to move up to more competetive racing -- this way the pilot would not have to buy another engine to move into Advanced and truly be competetive.

Stan

Jezmo

Stan you are right on the money. Only thing I have found a slight difference with is the run time befoe the ring seats. My last 51 took almost 2 gallons however none of my 40's took more than two tanks before they would idle well. I wonder if there is some inconsistancy in the assembly that causes some of the rings to distort just a smidge and require more time before they seat. I haven't bought a new one in at least 6 months although I am picking a new one up Monday so it's good to hear about the idle needle. It may take longer to break in than my others too.

Also, I hve found very few people who know about turning the spray bar to adjust the mid-range mixture. Bax has a good writeup on tuning the ST carbs in the Factory support forum. Anyway have a great day and weekend all.

Ken Erickson

This will stray off the theme of this thread. But, . . Whether LAs are available is a BASIC and "How to break-in a Super Tigre" is a detail. The thread has already swayed to the question of "Which engine. . ."

1. Is there anyone other than South-Central Texas, who has the "Advanced", Ball-Bearing .40 class?

I ask, because I know the guys in Florida do not use this class. It is my personal belief that they have got it right. Doug Bebensee has written of the Tennessee races where they have a class with TT 42 GPs on Quickees and he is promoting a Club 40 class with those same engines on Skyraiders. Don has written of the "hard sell" to get people to buy .40s.

Florida Guys: - What do you see as the next step, for those of you who want to race a bit faster?

2. During a discusion at our race today, Chuck said , "It is only the blue LAs that are going away.". This is what Don and I were told several weeks ago. Perhaps we do not need to find a substitute. My LHS owner told me that the OS LA is the most popular engine, period.

Carol and I will be moving to Columbus, IN in late October. I am hoping to get Club 40 started there within the next year. At this time, I am wanting to do it with small-frame, bushing engines. For new engines, that means LAs, unless we can get a ruling and/or waiver for the TT GP.

Monday, I will make the phone calls again. Will report back what I am told about future LA availability.

Ken Erickson


You do not necessarily have to go fast to race. But it is more fun.

Tony Stewart did not start out in NASCAR. Most NASCAR drivers started in go-karts.

gunfighter

My Feedback: (1)

Well...I just looked at Tower's web site and they now list the LA 40 Blue AND Natural as discontinued!

I am sure there are still quite a few in hobby shops around the country so it may be a while before the supply dries up. It still brings up the question of a replacement engine.

There are very few choices available in a bushing engine, but I want to ask a question.

Why would any one mandate a Bushing engine (i.e. GP 42) that will wear out faster, AND costs more than the ST GS .40 (with 2 ball bearings), when a simple prop change will net the exact same performance??? We are all trying to control costs so why not start with an engine that will work in BOTH classes by simply changing props and / or Nitro?

The GP 42 is $64.99, The ST GS 40 is $49.99. $15.00 cheaper and has been around forever.

I'm not trying to change what is currently working, just thinking about the future and groups that have not started yet.

stanlattrell

Jezmo, I tried to find the description on spray bar tuning for mid-range by Bax, but couldn't locate it. Could you point me in the right direction?? I'd like to read what he has to say on the subject........

Stan

Jezmo

Here it is. It has a link that points to the SuperTigre site and the last line pertains to rotating the spraybar for mid range adjustment. They speak of moving it a little but don't be shy, turn it whatever amount makes it run good.

http://www.rcuniverse.com/forum/m_1579985/tm.htm

DonStegall

My Feedback: (1)

I got a chance to start breaking the ST GS-40 in yesterday afternoon. I left the idle at the factory set position. I did not do my usual prep of taking the backplate and head off and washing out the engine. Since one of the goals is testing for "newbie friendliness", this did not seem appropriate.

I wanted to be able to know the rpm's relative to a 424 engine, so I used an APC 9x6 Sport prop. Plus the crankshaft is 0.275" where the prop meets the drive washer, and I wasn't about to ream out my 7.8x6 carbon fiber break-in prop I use on the TT Pro 40's.

Starting was no problem. Full throttle running was no problem. I settled on 14,000 as a good initial break-in speed. The engine will idle fine. However, transition is not good at this point. Which was two full 8 ounce tanks of Omega 15% with 4 ounces of castor added. Quite a bit of sputtering in the transition. I had a club meeting to get to, and I ran out of time. I will be putting it back on the test stand this afternoon.

My initial impression is that this engine is not as newbie friendly as the TT Pro 40 or the OS 40LA. However, if it survives lean runs better than the ABN engines, that opinion may change.

Some news on the O.S. LA front. It appears that new versions of the LA engines are now available. Unfortunately, the 40LA seems to be no more. There is a new O.S. 46LA available. See the page at [link=http://www.towerhobbies.com/products/os_engines/osmg0010m.html]O.S. Engines® LA Series[/link] (Note: After a more careful examination of the Tower site and the O.S. site, it looks like Tower is just repositioning the LA line and the engines have not changed.)

Chuck, to answer your question about why to use the bushing engines. Maximum possible performance is the answer. The bushing engines are constrained in their performance because they have smaller intake sizes than the sport BB engines. They simply can't perform as well as the engines with the larger intakes. But perhaps specifying a particular prop (and engine?) is just as good.

dwbebens

Greetings from Nashville;

Ken;

I've not heard anything about the Florida group wanting to start any kind of "advanced" class.

Gunfighter:

The reason we in Nashville are using the TT GP 42 engine for our Club 40 is that we already specify that engine in our Q-400 class (424 planes). Our thinking was that if someone wanted to move up from Club 40 to Q-400, they already would have an engine. We've found that the TT GP 42 engine is noticeably more powerful than the OS 40 LA. In defense of bushing engines, you don't have to worry about rusting bearings or disintegrating retainers, etc. Anyway, I'm just glad to get Club 40 going in this area - - using any engine - - if that's what it takes. As you guys already know, once you get Club 40 going, it expands very rapidly. Having this class going in our area should, in the long run, improve the "health" of our other three classes (according to the "trickle-up" theory).

Don;

What does "repositioning the line" in reference to the LA engines in your last post mean? Are they still making the 40 LA? Are they phasing them out? Are they terminated? Are they developing a new version of the 40 LA? Do we really have a problem? What is your best assessment of the situation? I looked at the OS site you gave and noted that the 40 LA wasn't even listed!

Since Tower Hobbies has discontinued the OS 40 LA, and if in fact, this engine will no longer be available, I would imagine the Florida group will eventually have to change their engine specs somehow.

I think the ST GS 40 is an excellent choice. I've had a number of ST engines and have also found that setting the idle needle was a little tricky to get right.

It just so happens that I'm going to Florida late next week for visiting etc, and I'll be racing with the Florida Club 40 group on Oct 13. I'll make some inquiries about 1) whether they are considering an "advanced" class and 2) what their plans are to replace the OS 40 LA. I'll report what I find out.

Doug Bebensee

gunfighter

My Feedback: (1)

Don and Doug,
As I said in my earlier post, I am not trying to change any thing that is currently working.
My point was, and still is, why buy an engine that is, at least in many folk's oppinion, inferior to another engine that costs less and will last much longer?
If you are using the GP 42 and it is holding up then by all means continue to use it.
I was looking at overall cost if the group ever decides to start an Advanced class. The pilots could move up with a simple propellor change.
My comments regarding another engine for the Novice class was / is based on the "probability" that the OS LA is discontinued and groups will soon be looking for another engine.

DonStegall

My Feedback: (1)

Doug,

At one point, Tower had most or all of the LA engines marked as Discontinued. I doubt if the blue LA engines were very popular, and eliminating them made sense. Even the 46LA Natural was marked Discontinued at one point. But now Tower has a page specifically for the LA engines. It must have been customer demand that warranted this action. Or maybe is just revamping the marketing of the engines.

I'm going to get in touch with Hobbico and Tower and get the definitive word on the 40LA. Maybe it can be brought back if it is in fact discontinued. I'm sure the tooling has not been destroyed, intentionally anyway. And with the numbers of 40LA's, it should be pretty easy to make a case for bringing it back.

I was going to get a GP42 to measure it and test it. The American sites still list it as .396 ci, but the Chinese site lists it as real close to .42 ci. Can you measure the bore and stroke so that we know for sure if it is in fact still a 40? It certainly looks bigger than an OS 40LA in the pictures.

Chuck,

I get your point about the engines. One thing that surprises me sometimes is that groups can even get together on a single engine in the first place. It takes some work to get guys to use a particular engine. Especially if they or a friend they have helped has had problems with one.

I hope the GS-40 is a good and reliable engine. The price is right. I thought I would not like the muffler, but right now, I don't see a problem with it. If it comes off in the air, that will probably change. I was surprised that the pressure fitting was not pre-installed on the muffler. No biggie, just a surprise.

All,

One thing people don't know is that I do a lot more testing than I talk about in the forums. I buy and try a lot of stuff because I don't make statements of fact unless I'm actually experienced enough to do so. And I'm just like everyone else, I form opinions. Some I share, some I don't. I try really hard to be right more of the time than I'm wrong.

Right now I'm working on an electric racing class a lot. And I've been doing more homework on RCPRO Warbird Racing, even though there is none in my area at the moment. But the majority of my R/C time has been on Club 40. And my work at promoting it locally is finally starting to pay off. And that takes even more of my time.

dwbebens

Don;

Well, imagine that. I checked the bore and stroke of my TT GP 42 engine and got: Bore = 0.844" and Stroke = 0.750" which gives a displacement of 0.4196 cubic inches!!!!! That may be partially why it runs a little better than the LA. I've just looked at a number of sites selling this motor and as you say Don, some sites list it as having 0.419+ cu in and others list it as having 0.39+ cu in.

Oh well, I'll bring this up to our racing board. They were of the opinion that it was a 40.

Doug Bebensee

DonStegall

My Feedback: (1)

I got a chance to run the Super Tigre GS-40 some more today. After another tank of fuel, I started adjusting the idle. I was able to get it to idle and transition fine. I did find out that just a little too lean on the idle and it won't run. A little too rich and it sputters on the transition. Not quite as forgiving as the TT Pro 40.

I started taching it and changing props to see what it likes. The props (all APC Sport) and numbers are:

9x6 - 15,200
10x6 - 13,300
10x5 - 14,100
9x7 - 14,700

I actually got 14,800 out of the 9x7 but burned a plug in the process.

The pitch speed for the 9x6 is 86 mph and the pitch speed for the 9x7 is 97 mph. But the drag of the Sky Raider Mach II is probably too much for the 9x7. It seems to be for the TT Pro 40, but the ST GS-40 may just be able to pull it.

DonStegall

My Feedback: (1)

Trying different props on the SuperTigre GS-40 was interesting. The APC 11x4 does slow down the Sky Raider Mach II some. Not as slow as an OS 40LA, but maybe enough slower for Club 40 Novice.

We tried an APC 9x6, but it was not competitive with the TT Pro 40's running on APC 9x6 props. We changed it to a 9x7 and got closer to the speed of the TT Pro 40. Maybe the engine is just not broken in well enough, but it seems to pull more than it likes to turn up. With the APC 9x6, I could not get it over 15,400.

Transition and idle have not been a problem.