RE: My 2300 only likes one prop
 

#1. I think the engine is great, so I don't know where you are reading that I slammed anything. The stock carb is not the best. I suggest that people try it before replacing it, but that if it must be replaced, it's still a very good value.

#2. You're welcome

RE: My 2300 only likes one prop
 

No, but all your inconclusive and one sided testing and comments long with it says that it is a POS. The engine does this and this and this (which is bad). The it does not do this and this and that (which is also bad). What is a person suppose to think? [sm=bananahead.gif]

RE: My 2300 only likes one prop
 

Clear out the area....... There's gonah be a FIGHT ---- NOT24 , CYCLIC is kinda right (YOU TRASHED THE ST 2300 GRACEFULLY) EVEN though you like it !!I would say that had I only bought an 18-6 prop, I would think this engine is junk,

RE: My 2300 only likes one prop
 

Cyclic Hardover and speedster 1919 - not true. NOT24 had a problem and addressed it in a logical manner and shared his results as he found them. This is a great thread - only spoiled by the sore heads! Gosh, it seems some people cannot see anything positve!

Paul

RE: My 2300 only likes one prop
 

OK we are not getting anywhere. Lets all go to another thread and cool off for a while.

Jim ----Moderator

RE: My 2300 only likes one prop
 

Yesterday I finally got out with my H9 Funtana 90 with the 2300 installed. This was with the Moki carb installed that I'd mentioned earlier in another reply on this thread. My setup includes a Graupner 15 X 8 three blade prop (wide blades) and a Perry pump. Using 5% fuel and an O.S. F type plug it ran flawlessy - good enough to easily 3D with it. I need to find a lower pitch prop as it doesn't have enough "bite" to pull out of a hover well, but I can hover it easily enough. I found that the Moki carb metered extremely well and the engine ran totally reliably - what a change from the stock carb! I had to shorten the stock muffler considerably to get it to fit without carving the plane up - as a result the muffler has considerably less volume than stock. Not sure how that affects things... Nice having a big S.T. that's more useful than just a pretty paperweight. I hope the carb swap has the same effect on my S.T. 3000 and 3250. A friend flew his Midwest Super Stinker yesterday with an O.S.7D carb on his 3250 - definite improvement there too. It's the carbs guys - the stock carbs just aren't the best.

RE: My 2300 only likes one prop
 

Everything I have ever read or heard regarding a 3 or 4 bladed prop is they are not even close to being as efficient as a two bladed prop. Is that 8 inch pitch a bit much for prop hanging?

RE: My 2300 only likes one prop
 

Prop clearance is an issue... besides, the only other prop I had that was close was a 16 X 8 two blade. Am going to see if I can find a 17 X 6 to play with... or better yet, a 5" pitch prop. Yesterdays experiment was to determine reliability. I got in either 3 or 4 long flights and a bunch of hovering and aerobatics. Pretty good days flying it was all around.

RE: My 2300 only likes one prop
 

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I am glad that you are finding some satisfaction with your G2300. Would you care to disclose the source of your Moki carb (assuming you bought it from a dealer, etc.)?

RE: My 2300 only likes one prop
 

You know, I said this somewhere before and that is I do not see the big stink on changing carbs on SuperTigers. It is a perfectly acceptable thing to do on car engines. I have done the 7d swap and its an instant change in performance. I also did Perrys and the same effect. Just don't like the needle valve setup. I am curious though, what size Moki is the one that works

RE: My 2300 only likes one prop
 

It's amazing how much difference a new carb can make on an engine that's not quite right. My engine has only three flights on it since the carb change, and a 16-8 prop works fine. I'd try it on the f90 if I were you. The 18-6 is nice on that plane, but I had a taller gear on mine.

The engine is still a bargain, even with a carb swap. Now we're looking at $250 including a new carb and a pitts muffler. It comes close to the 160FX for power, it's lighter, and it's $100 cheaper.

RE: My 2300 only likes one prop
 

Moki carbs available from Just Engines in the UK. http://www.justengines.unseen.org/ Paul is the owner. Tell him it's for a S.T. - 17mm diameter mounting flange BTW. I believe it's a Moki 1.35 carb. He gave me an excellent price compared to what an O.S. 7D carb goes for.

RE: My 2300 only likes one prop
 

I got three more flights on my 2300 today. Now I have a new cowling on my Sukhoi, and the weather is much warmer. It seems as if the engine may be overheating, because after about 5 minutes, it starts popping. I've never had overheating occur before, so I don't know what the symptoms are. It's not lean, because I richened it way up for the second flight, and it made no difference. The first flight it was set rich as well, but it had a clean accelleration.

This cowl is different from the other one in two ways. It has no exhaust in the cowl itself, just the 5 slots in the belly pan. My original one had a big hole in the bottom.

The venturi is very close to the ID of the cowl ring. In other words, you can't prime it by putting your finger over the carb. I had cleared this away on my other cowl, but chose not to on this one, because of looks. If this were causing my problem, I would expect it to do it all the time.

If cooling is the issue, which is the best place to cut an exhaust opening? Should I hack open the lower cowl, or should I cut a hole over the cylinder head? My guess is the flow will be better if I make a bigger exhaust outlet underneath. Cutting a hole over the head won't really aid in airflow through the cowling. I'm open to suggestions.

RE: My 2300 only likes one prop
 

The "big hole in the bottom" is the way to go.

I have not looked back to be sure exactly what Sukhoi model you're flying. But I've done a few Sukhois, and anything in the 72" ws size and up, I've dammed up the front cowl opening everywhere except right in front of the cylinder, and also opened up the cowl if needed to provide direct airflow to the carb intake. If the top of the cylinder head is close to the inside surface of the cowl (an inch or less), I'd probably cut away the area directly over the head.

I haven't actually measured, but let's say you dam the front of your cowl. Whatever space is directly behind the spinner I would not count for intake area. Let's say you cut an opening in the dam 2" x 4" right in front of the cylinder. That's 8 sq in of intake area. I would want three times that area for hot air exhaust, so 24 sq in, or an opening in the bottom 4" x 6" or thereabouts. If you put it at the bottom of the cowl, somewhere in the vicinity of the muffler, it will detract very little from the appearance in the pits.

I tend to worry hardly at all about appearance in the pits, because I am not a scale modeler, and beat the crap out of my planes... but I do care about how they fly, and how well the engine performs.

I've seen what strikes me as some skimpy hot air outlets that seem to perform OK, and I've seen some rules of thumb that call for outlet area only twice the intake area.

Consider that the front of the cowl is a high pressure zone, and the underside is a low pressure zone. Whatever air moves in the front will be sucked out the back, but it will expand in volume as it carries heat away from the engine. Air that enters the front but does not flow over the engine is worse than useless, because it occupies exit stream volume without cooling your engine. Damming is the simplest way to stream all your incoming air directly over the engine. Other guys insist that damming is not enough, that you have to actually baffle the whole space around the engine except for 1/4" outline, so every bit of air will be forced to pass across the engine surface. I accept the theory, but have never had an IC engine that needed that kind of treatment.

If you don't have an infrared temperature probe, it's a cheap enough investment for anyone flying larger engines, and will ease your mind with any question of engine overheating. I usually find my engines register a lower temperature when they're cowled and flying (just after landing) than on the test stand with no cowl.

This is my first posting on your thread, so let me say I've followed it with close attention, and thank you for your persistence on a worthy subject.

RE: My 2300 only likes one prop
 

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You have to realize that some of us are old enough to have heard others make similar claims (that ST carbs were junk) many, many years ago when the carbs were just fine. My last G2300 (Italian) that I flew had a great carb, while others were talking about the piece of junk carbs. Why was my engine different? The only thing that I can think of is that I broke it in on the bench with many, many, many tanks of fuel ran through it. It was "bouncy" when I finally put it on a model. That "may" have had something to do with it. But it might not have, just as easily.

This is not to say that more recent carbs did not/do not have problems. I know you guys know your stuff (Daryl), so I'm not doubting what you say. I'm just trying to explain why some of we old timers are having problems believing this stuff when we first hear about it. We do know that the later Italian engines had problem carbs for a fact.

I do have at least one NIB G2300 Mk. II left on the shelf. If it turns out to have an unusable carb, I will proceed to drive Hobby Services nuts until they make it right. Why? Because I know for a fact that these carbs can be made to function properly. If, after driving them nuts, I get no satisfaction (unlikely), I won't hesitate to obtain another carburetor for this engine. Which one? That I don't know. Probably a Perry. I've never had a Perry that couldn't be made to perform properly if it was the right size for the engine. At the very worst, I may have to replace the o-rings.

While I love OS engines and particularly OS carbs, they would have to make me one heck of a deal for me to buy one for this engine. I'm tempted to lean toward a Magnum carb, but after I saw the chart of available throat and neck sizes available for Perry carbs (it's staggering), that is probably the way that I'll go. When I finish getting the right carb, I will not need a Perry pump or a regulator unless I put the tank back on the CG of a really big model.

I just ordered five $110 JR servos for a 3D machine. Does that mean I'm hooked on 3D? <G>

RE: My 2300 only likes one prop
 

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What Majortom said.

Also, if you are not running 5% nitro, borrow a tank from a friend and don't forget to readjust the needle valves. Both of them.

The exhaust opening for cooling air needs to be three times larger than the intake opening (hot air expands).

Majortom's idea of blocking off the cowl except where the air hits the engine directly is a good idea, second only to installing baffling inside the engine compartment to guide the air through the cylinder fins. If you can get by with just the baffle in the front, all the better. It's much less work.

RE: My 2300 only likes one prop
 

Thanks guys for the replies. I appreciate them.

Looks like I will start by opening up the cowl. I also don't care much about appearances, so this won't bother me that way. The original cowl was abs, so it was much easier to cut than this glas one. This is a Goldberg Sukhoi, which really flies great, I might add. Still a little nose heavy, and it has pitch coupling in KE, but it's a fun plane to fly.

When I did my nitro testing, I tried 0,5,10 and 15%. I found that the minimum nitro that performed well was 10%. Anything less really wasn't acceptable. The idle and acceleration suffered on less than 10%.

I have flown this engine on a F90, uncowled, with the Magnum carb. I did a lot of prop hanging and it didn't act any different at the end of the flight. That is the primary reason I suspect overheating now. So I will cut it open and try again.

RE: My 2300 only likes one prop
 

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Fuel recommendations are only generalizations at best. If your engine prefers 10%, then that is what I would use too. Every once in a while an engine leaves the production line with tolerances stacked a little further one way than the other. My 5% recommendation will work with the majority of G2300's at sea level. But such things as prop size, type of fuel, glowplug, etc., can make a difference too. Glad you got it running right. I agree with your heat hypothesis. Let us know how it goes.

RE: My 2300 only likes one prop
 

If I may suggest something, may not be the problem but it did happen to me a few years ago on a G90. My fuel lines coming out of the firwall were simply routed to the carb nipple. Skipping past all the overheated deadsticks. Turns out the fuel line was pinched enough to cause a lean run and within a couple minutes after takeoff, It was in the dirt. Didn't look pinched but it was enough. Most pilots here have darn near most of the bottom area of their cowls (stylishly) cut open for a very good airflow.

Run ups on the ground prior were fine. Could be one thing such as ventalation or a combination of minor errors leading up to a healthy overheat. Here at 5000ft on 90degree day an 8000ft DA. Overheating is common.

RE: My 2300 only likes one prop
 

Let me ask you this about that. When an engine overheats, what exactly does it do? Does it sound like it is running lean? What does the exhaust note do?

I ask this because I know too lean a mixture can cause overheating, but can overheating cause too lean a mixture? Maybe this sounds strange, but I have never dealt with overheating before. I have dealt with poor fuel supply, and lean runs.

RE: My 2300 only likes one prop
 

Had another go of it today after cutting open the cowling. None of the previous issues arose. I cut out a hole in the lower cowl, one over the head, and also cleared the area in front of the venturi. Just for kicks, I took a head temp reading right after landing. It was showing 118 degrees. I'd like to know the best way to get a good honest temp reading. Should it be done with the engine running? At what power setting? Before or after flight? What is the highest temp that would be considered normal?

I flew on 10% and 5%. There was no perceptable difference in the way it ran, and the needle settings were very similar. I do feel the 10% makes a tad more power, as I was 300 revs lower on the 5%.

BTW, this Goldberg Sukhoi (kit) was a bear to build, but I'm starting to feel it was worth it. This plane flies very well on this engine at 11 lbs dry weight. I like it much better than the Funtana 90.

RE: My 2300 only likes one prop
 

Often a over heating engine will get a ragged sound to it. It may even miss some in a down run right as you level out.

Sometimes, they just seize up and quit.

RE: My 2300 only likes one prop
 

Not sure if your asking me but I'll tell you what happened to me. I have had a few engines overheat from time to time. Different brands but all did the same thing. I'm flying along and I find myself increasing throttle becuase the plane keeps slowing down. You don't have much time to react. You need to realize whats happening fast and land. By the time I get on the ground, the engine is at an idle and my throttle is full forward. Been the same scenario for me everytime.

RE: My 2300 only likes one prop
 

Pretty Sukhoi. Cutouts look good. Not to quibble, but next time I'd make rounded rather than square corners, to avoid stress concentrations. I usually lay in a patch of 2 oz fiberglass anywhere I think a crack might start.

Goldberg Sukhoi kits have a strong following, but they need a lot more power than the .90 two-stroke that the manual recommends. I still have three of those kits upstairs. It just wouldn't do to run out of Sukhois.

Glad to hear your issues have gone away. After all your work, you deserve a lot of trouble-free flying!

I take my temperature readings at full throttle on a warmed up engine, shooting the glow plug if it's visible, or as close to that as I can get. Anything in the mid-200's and I'm happy. When I have cause for concern, I check after a flight, without shutting down, just get it back in the pits and run it up again. I see one guru calling for crankcase temp of 325-350˚ for best power (to vaporize the fuel mixture for complete combustion), but I've never had an engine read that high. Normally I only check temps when breaking in a new engine, or when trouble arises.

RE: My 2300 only likes one prop
 

Thanks all. Yeah, I know about the round corners, but I did this at home where i don't have all my tools.

I'll take its temp again when at full throttle to see where I'm at. I think it'll be fine. This engine amazed me yesterday. Both starts were one flip by hand. Never had an engine do that before, both cold and warm.

Can anyone tell me how loading a well broken in engine with a large prop will affect the engine? I may like to experiment with larger props again, but I think the engine still would rather spin up around 9k, rather than the 7500-8k that Bax suggests. I have good speed with the 16-8, but would like a little more thrust, if i could get it.