Aloft Forums
Welcome to Aloft Forums. Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!
The Glow Engine (Model AIrcraft Engine)
- Thread starter Konrad
- Start date
Konrad
Very Strong User
Gumming up the valve train? Gen Saito early on recommended not using castor oil in his four cycle engine. Later we learned this was because he didn't want his tech's cleaning parts for warranty claims. Later with all the bearing failure castor oil was approved.
Satio has been very good about their warranty program. In fact it is part of their acceptance criteria. What I mean is that the big bore Saitos have the valve seat cut directly into the aluminum head (there are no bronze valve seat inserts). Now Saito air pours their aluminum castings, as a result there is a lot of porosity in the casting. Unfortunately these voids often find their way across the valve seat. Saito has been very good about warranting these manufacturing defects. About a 1/3 of my large bore Saitos have had these issues with the valve seat. Saito has covered these with no issues. It would be hard to deny that the valve is not sealing when one can see the casting voids across the valve seat. I've been using Saito engine going way back the the big head 1.20
I can't think of the last time I had a real issue with gummed valve trains. Rusted solid bearings and parts yes, but gummed up valves that I couldn't loosen up with some heat and alcohol in 5 minutes no.
I've had no issues with 100% castor fuels and really stuck gear trains. Heck going down to 50% castor oil has shown no issues with the bearings. Some of the 3% castor mixes haven't been worth it.
Try 3% nitro and maybe even zero. I think most folks would be surprised at how little power is lost. The added methanol might actually make the engine more tractable.
There is an OS Surpass 52 in there that I might want to resurrect.
All the best,
Konrad
Satio has been very good about their warranty program. In fact it is part of their acceptance criteria. What I mean is that the big bore Saitos have the valve seat cut directly into the aluminum head (there are no bronze valve seat inserts). Now Saito air pours their aluminum castings, as a result there is a lot of porosity in the casting. Unfortunately these voids often find their way across the valve seat. Saito has been very good about warranting these manufacturing defects. About a 1/3 of my large bore Saitos have had these issues with the valve seat. Saito has covered these with no issues. It would be hard to deny that the valve is not sealing when one can see the casting voids across the valve seat. I've been using Saito engine going way back the the big head 1.20
I can't think of the last time I had a real issue with gummed valve trains. Rusted solid bearings and parts yes, but gummed up valves that I couldn't loosen up with some heat and alcohol in 5 minutes no.
I've had no issues with 100% castor fuels and really stuck gear trains. Heck going down to 50% castor oil has shown no issues with the bearings. Some of the 3% castor mixes haven't been worth it.
Try 3% nitro and maybe even zero. I think most folks would be surprised at how little power is lost. The added methanol might actually make the engine more tractable.
There is an OS Surpass 52 in there that I might want to resurrect.
All the best,
Konrad
Last edited:
Konrad
Very Strong User
If you like 15% in the Hawk you should try 25% just to see what happens. The Hawk's head has no squish band. As a result there is much less turbulence to help with the atomization of the fuel. With this style head, nitro if often a major benefit. Are you still using the butterfly carb or has the engine been upgraded to the MK-X carb? You might notice that the cylinder is one piece with the cooling fins. This helps get rid of the heat you might notice with the higher nitro.
As to the other engines I've never notice that they were sensitive to the 5% change in that area of mixture (5% to 15%). Yes, I've seen a marked change from zero to 5% nitro. Are these engine equipped with auto-mixture carbs or are they using the simple airbleed carbs?
I find nitro both a power booster and tuning crutch. To the last part I try to find what is the underlying issue and address it (often with a change to the combustion chamber or carb.
All the best,
Konrad
As to the other engines I've never notice that they were sensitive to the 5% change in that area of mixture (5% to 15%). Yes, I've seen a marked change from zero to 5% nitro. Are these engine equipped with auto-mixture carbs or are they using the simple airbleed carbs?
I find nitro both a power booster and tuning crutch. To the last part I try to find what is the underlying issue and address it (often with a change to the combustion chamber or carb.
All the best,
Konrad
Last edited:
Konrad
Very Strong User
A bit more follow up on castor in the use of four cycle engines.
Per the 2009 manual Saito wants fuel with 20% lube & 10-15% nitro. Fuels composed entirely of castor oil is NOT recommended. A mix of synthetic-castor oil is acceptable. Please note that 100% castor is NOT disallowed.
In my 1983 big head 1.20 Saito recommended against castor oil. We learned latter this was a manpower issue with warranty claims. By 1986 Saito was recommending that the 20% lube be made up of 30% castor and 70% synthetic. This was as a result of the horrible premature cold corrosion (bearing failures). Gen Saito still wanted to see synthetic in the oil mixture as most synthetic oils have a strong detergent action. (This is counter productive against the coating action of Castor). This is why castor oil give better protection against corrosion than most synthetics. It actually coats the surface. Most synthetic oils have a higher film strength (this is a good thing) but as the engine goes lean and overheats they often vaporize leaving no protection (lubrication). Castor oil offers much much longer protection against metal to metal wear in a lean hot run.
Nitromethane in a four cycle engine is of dubious value. Many manufactures of high performance ( proper scavenging engines) like Laser disallow its use! Yes, it can add power but its cost both monetary and in engine longevity is too high.
From a historical perspective OS recommended very low oil content for their early four cycle engines. I recall model engine 4 cycle fuel having oil content levels as low as 8%. This was done as the power (heat) was low and they were trying to keep the glow plug from being drowned (cooled).
Today please don’t use the 17% oil mixture so popular in today’s 2 stroke fuel! Just for the record I like and use 20%+ oil in all my toy engines. And yes, most of these blends are with 100% castor oil. YS engines are the one exception as the gummed castor oil can tear the silicone diagram.
Castor oil does not result in a major issue with sticking valve gear. Should there be an issue it is easy to correct with heat and some solvent (methanol). No need to disassemble the engine.
Per the 2009 manual Saito wants fuel with 20% lube & 10-15% nitro. Fuels composed entirely of castor oil is NOT recommended. A mix of synthetic-castor oil is acceptable. Please note that 100% castor is NOT disallowed.
In my 1983 big head 1.20 Saito recommended against castor oil. We learned latter this was a manpower issue with warranty claims. By 1986 Saito was recommending that the 20% lube be made up of 30% castor and 70% synthetic. This was as a result of the horrible premature cold corrosion (bearing failures). Gen Saito still wanted to see synthetic in the oil mixture as most synthetic oils have a strong detergent action. (This is counter productive against the coating action of Castor). This is why castor oil give better protection against corrosion than most synthetics. It actually coats the surface. Most synthetic oils have a higher film strength (this is a good thing) but as the engine goes lean and overheats they often vaporize leaving no protection (lubrication). Castor oil offers much much longer protection against metal to metal wear in a lean hot run.
Nitromethane in a four cycle engine is of dubious value. Many manufactures of high performance ( proper scavenging engines) like Laser disallow its use! Yes, it can add power but its cost both monetary and in engine longevity is too high.
From a historical perspective OS recommended very low oil content for their early four cycle engines. I recall model engine 4 cycle fuel having oil content levels as low as 8%. This was done as the power (heat) was low and they were trying to keep the glow plug from being drowned (cooled).
Today please don’t use the 17% oil mixture so popular in today’s 2 stroke fuel! Just for the record I like and use 20%+ oil in all my toy engines. And yes, most of these blends are with 100% castor oil. YS engines are the one exception as the gummed castor oil can tear the silicone diagram.
Castor oil does not result in a major issue with sticking valve gear. Should there be an issue it is easy to correct with heat and some solvent (methanol). No need to disassemble the engine.
Last edited:
I have a boat load of 20% nitro and 20% synthetic fuel for my 4 strokes that I will be using for a long time. I will test one of my Saitos with 5% to see how it works so that when the day comes and I run out of the 20/20 fuel, I can switch to 5/20.
For my Fox Hawk, I swapped carbs on it with the newest version because I am running it with a Jett tuned muffler and the old butterfly carb couldn't handle it for some reason.
For my Fox Hawk, I swapped carbs on it with the newest version because I am running it with a Jett tuned muffler and the old butterfly carb couldn't handle it for some reason.
That might be a good idea to dilute down from 20/20 to 10/10/10. The NovaRossi's recommend 10/10/10 (nitro/synthetic/castor).
Meanwhile, here's my previous build project with a Fox Hawk 60. It has the latest Fox carb and a JettStream muffler with a 2-piece adapter. Notice that the muffler adapter is more elaborate than a normal one because the stock muffler mounts with 4 bolts to the engine. I have not flown it yet and I hope the adapter holds up. It worked well on the bench. The plane is an UltraSport 60.
Meanwhile, here's my previous build project with a Fox Hawk 60. It has the latest Fox carb and a JettStream muffler with a 2-piece adapter. Notice that the muffler adapter is more elaborate than a normal one because the stock muffler mounts with 4 bolts to the engine. I have not flown it yet and I hope the adapter holds up. It worked well on the bench. The plane is an UltraSport 60.
I did have concerns about the small tabs. For strength I would have to JB Weld a tube as you mentioned from the tabs to the exhaust face. But that will look ugly, but better than damaged engine.
This would not be a concern with the small stock muffler. Plus the stock muffler wraps over the exhaust face the old fashioned way.
This would not be a concern with the small stock muffler. Plus the stock muffler wraps over the exhaust face the old fashioned way.
Konrad
Very Strong User
Yep!
Now, I've never liked or had much luck with JB weld (Metalized epoxy). A tube held captive between the ear and muffler adapter should add some support should the muffler get hit on landings. I find that I can shape epoxy fillets rather well with a wet finger. Not that JB Weld will hold up well to the heat on that exhaust stack.
Now, I've never liked or had much luck with JB weld (Metalized epoxy). A tube held captive between the ear and muffler adapter should add some support should the muffler get hit on landings. I find that I can shape epoxy fillets rather well with a wet finger. Not that JB Weld will hold up well to the heat on that exhaust stack.
Johnnashville
Active User
Konrad, I have not had an opportunity to run any of the great engines of the past. Back in late 70's 80's just getting a look at one in a glass case or reading about one in a publication was it . We did manage to scrape enough quarters together to trick out our cox td .051's, kustom kraftmanship needle valves, pressure back plates, and globbee heads. We flew our Ace GLH's and quicky 200's to death, but back then, we had to walk or ride our bikes to the field. Later on, I did get some K and B, Fox, and OS engines, but nothing I would call performance.
For the last 15 years or so my nitro flying has been about low to mid range throttle response for 3D. I have run Saito, YS, and OS. Currently, for me, the OS 120 set up on what we call a beer can pipe is the e-ticket ride. I can't take credit or even pretend to know the physics of this setup, but I love it. The saitos are great too, but the YS engines have stole my lunch money, kicked my ass, and laughed at me on the way out. But others have had outstanding performance with the YS engines in the 3D realm.
Konrad
Very Strong User
LOL, I'm not much older than you.
GLH: I flew Undertakers
I never understood why Cox didn't fix that needle valve in the first place, KK made the TeeDee actually usable. I think all I have left are a few 0.010 Tee Dees.
That mousse can muffler, Are there internal features like an internal stub pipe? Or is just what we see a long extractor going into an expansion chamber?
GLH: I flew Undertakers
I never understood why Cox didn't fix that needle valve in the first place, KK made the TeeDee actually usable. I think all I have left are a few 0.010 Tee Dees.
That mousse can muffler, Are there internal features like an internal stub pipe? Or is just what we see a long extractor going into an expansion chamber?
Last edited:
Johnnashville
Active User
No internals,
Oh man, just came across this thread. A trip down memory lane. Coincidentally, this past winter I was de-junking the shop and came across my old O.S. .61 FSR's. Both with the substituted ST Mag V carbs. Lots of degunking later, they cleaned up perfectly. I was suspicious of the bearings, but Boca Bearing had them in stock. This thread has me motivated to do the final assembly - I have no doubt they will run perfectly again. Hmmm..now to find a couple of suitable airframes.....
Konrad
Very Strong User
There have been times that I wished that all toy engine manufacture would use the ST Mag V for all their sport engines. The ST Mag-V is that good a carb! It even has a hidden midrange adjustment in that clocking the discharge port (cat’s eye) will effect the fuel draw.
As much as I like the rod in tube design of the ST Mag V, OS did get the tube over slot (comma) design to work rather well.
I have to ask why change the bearings? If I was running castor oil I rarely have to change out bearings. Ok, if I have a prop strike or worse but not as a result of day to day use. Now fuels with with no castor oil often resulted in corroded bearings if proper storage procedures weren’t adhered to.
I love getting engines that are locked up solid with old castor oil as this is an indication that there is little corrosion on the ferrous part. With engines that have been stored with castor oil one needs to free the rolling elements before running the engine. allowing the rolling elements to skid can damage (flat spot) them.
I had a detailed thread on a now defunct web site where I went into great detail about the model airplane carb. I’ll have to see what I have of that discussion.
As much as I like the rod in tube design of the ST Mag V, OS did get the tube over slot (comma) design to work rather well.
I have to ask why change the bearings? If I was running castor oil I rarely have to change out bearings. Ok, if I have a prop strike or worse but not as a result of day to day use. Now fuels with with no castor oil often resulted in corroded bearings if proper storage procedures weren’t adhered to.
I love getting engines that are locked up solid with old castor oil as this is an indication that there is little corrosion on the ferrous part. With engines that have been stored with castor oil one needs to free the rolling elements before running the engine. allowing the rolling elements to skid can damage (flat spot) them.
I had a detailed thread on a now defunct web site where I went into great detail about the model airplane carb. I’ll have to see what I have of that discussion.
One was put away dirty from a crash, probably 25+ years ago...it looked very good after it was all cleaned up. But I couldn't seem to get a bit of "roughness" felt in the bearings to go away. Might be tiny bits of castor goo, might be a few grains of sand mixed in, might be rust. If it was a less respected engine, I would have assembled and just seen what happened after running it. But new bearings were cheap....
Even found the header and tuned pipe (slightly dented from the crash) used on one of them.....
Even found the header and tuned pipe (slightly dented from the crash) used on one of them.....
Konrad
Very Strong User
Well respected, hum. Well marketed, yes.
Most will agree that the OS FSR might be the pinnacle of the OS sport engine. She sported Schnuerle porting and a rather good auto-mixture carb. In the sport arena she was competing with the baffle K&B 61* with Perry carb. Or the Fox Hawk and Eagle engines with their non-standard butterfly carbs. The 15% premium in price over these engine was well worth it for a sport engine.
Crashes or sudden stops of the crankshaft would give me cause to look at the bearing in more detail. I put little value in how the bearing “feels” in an unloaded state. I look for irregularities with the bearing while lightly loaded axially and radially. I’ve seen far too many engines damaged while trying to replace bearings. I usually make up a set of bearing tools (mandrels) to allow pushing the bearing without needing to go through the rolling elements.
I see with the term "Tuned Pipe” that you and I were looking for more than a sport engine with our FSRs. And this is where the OS FSR fell flat on its face, compared to the European engines like Rossi, Super Tiger, Webra and a host of other brands. While the schnuerle porting did add a lot of power over the baffle sport engine. In and of itself this was not enough to make the FSR pull the pattern plane with the authority we expected from a piped 10cc engine. The 15% discount against the ST and Rossi sure was seductive. But when it came to the objective measure of the power to turn the prop, it was clear the OS FSR was a second tier engine to the Italian Stallions with their inflight mixture control and true ABC P&Ls.
This brings up a sore spot with OS Engines the corporation, OS Engines was practicing deceitful marketing with their term "ABC type” to identify their ringless nickel plated P&L technology. After about the 3rd gallon of fuel we sure learned the ABN (AKA, ABC type) was no match for the true hard chrome ABC P&L found in reputable engines.
Yes, I still have a few OS FSR where I tried to make a silk purse out of a sow’s ear with the use of Shadel/Nelson true ABC P&Ls as marketed through Performance Specialty.
*The Lee Custom K&B 61 could run with the OS FSR and many other sport schnuerle ported engines. But the use of a pump and pump carb put the Less Custom outside the area of sport engines.
BTW; I think the CMB 60 is the epitome of the short stroke 10cc Pattern engine.
All the best,
Konrad
Most will agree that the OS FSR might be the pinnacle of the OS sport engine. She sported Schnuerle porting and a rather good auto-mixture carb. In the sport arena she was competing with the baffle K&B 61* with Perry carb. Or the Fox Hawk and Eagle engines with their non-standard butterfly carbs. The 15% premium in price over these engine was well worth it for a sport engine.
Crashes or sudden stops of the crankshaft would give me cause to look at the bearing in more detail. I put little value in how the bearing “feels” in an unloaded state. I look for irregularities with the bearing while lightly loaded axially and radially. I’ve seen far too many engines damaged while trying to replace bearings. I usually make up a set of bearing tools (mandrels) to allow pushing the bearing without needing to go through the rolling elements.
I see with the term "Tuned Pipe” that you and I were looking for more than a sport engine with our FSRs. And this is where the OS FSR fell flat on its face, compared to the European engines like Rossi, Super Tiger, Webra and a host of other brands. While the schnuerle porting did add a lot of power over the baffle sport engine. In and of itself this was not enough to make the FSR pull the pattern plane with the authority we expected from a piped 10cc engine. The 15% discount against the ST and Rossi sure was seductive. But when it came to the objective measure of the power to turn the prop, it was clear the OS FSR was a second tier engine to the Italian Stallions with their inflight mixture control and true ABC P&Ls.
This brings up a sore spot with OS Engines the corporation, OS Engines was practicing deceitful marketing with their term "ABC type” to identify their ringless nickel plated P&L technology. After about the 3rd gallon of fuel we sure learned the ABN (AKA, ABC type) was no match for the true hard chrome ABC P&L found in reputable engines.
Yes, I still have a few OS FSR where I tried to make a silk purse out of a sow’s ear with the use of Shadel/Nelson true ABC P&Ls as marketed through Performance Specialty.
*The Lee Custom K&B 61 could run with the OS FSR and many other sport schnuerle ported engines. But the use of a pump and pump carb put the Less Custom outside the area of sport engines.
BTW; I think the CMB 60 is the epitome of the short stroke 10cc Pattern engine.
All the best,
Konrad
Last edited:
