mr.scale

My Feedback: (4)

does anyone knows what is the best break in and 3Dprop fpr a G90. And what is the best nitro content for this engine, i currently have 5%nitro,powermaster...
thanks

FLYINGFOOL*2007

Mr.Scale,
Bolt on a 12x8 and run it "fat" at full throttle for around 16oz. let it cool, fire it back up and lean it to full rpm and give it one or two clicks to the fat side and you are ready to fly. you may need to make small adjustments from here but it will be ready to go to work with out any further break in.
as for what prop to use, listen to the engine, let it reach full rpm what ever prop you use.

Fly it like it ain't yours![>:]

FLYINGFOOL*2007

Mr.Scale,
I missed the fuel. 5 percent should be fine, i tend to use 10 in engines around that size but use the 5 and see how it likes it. try to stick with one after finding what it likes.

mr.scale

My Feedback: (4)

thanks.. I ordered the engine tdy and i just learning ST brand!!!
cool I'll try a 12x8 and a 13x6....

NM2K

My Feedback: (14)

After following the manufacturer's instructions for break-in, use the setting technique below to set your model's needles.

Set your needle valves with only an of fuel in the fuel tank. Hold the model's nose from 45 Degrees from horizontal or straight up and then set your needle valves for a slightly rich high speed and a perfectly tuned low speed that is neither lean, nor rich. Each time you change propeller brands or diameter and pitch numbers, you need to go through the set up process again, or you may burn up your engine. Ditto when it comes to changing fuel brands/nitro percentage, or glow plug brands/models.

The idea is to tune your engine's high speed needles so that the engine is not running lean at the end of the flight. Yes, your mixture will be rich at the beginning of the flight, but being rich will not harm your engine, so just hang in there and within a minute or so, the rich mixture will subside and the mixture will be satisfactory. You will be surprised how much longer your engines will last using this technique. Also your models, since your engine will not lean out, overheat and stall before it is time to land.


Ed Cregger

flyingagin

I concure with what NM2K has stated. Bought my 1rst Super Tiger back in the late sixties, presently have 3, a 34, a 90, and a 3000. I love ringed engines for their longevity. They get a bit tired i can replave bearings and ring after properly honning the sleeve. Then another PROPER breaking and many more years of enjoying my Super Tigers.

mr.scale

My Feedback: (4)

So what is the prop that mos people use on the G90, it seems that the 12-8 is kinda small..i'm leaning towards the 13-6 and then a 14-5 or something, any way i'll get a assortment of props,hehe!!
thanks

flyingagin

I run 13x6 to 14x6 on my 90. Depends a great deal on the airplane.

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How is the sleeve properly honed?

Thanks,

Capt. Buford

flyingagin

I have used fine sand paper with oil 400 on foam like you usr to mount your reciever in. You have to glue them to the foam and that on a dowel. Take a few spends in the cylender bore maybe 6. You will have to search this thread, [link]http://www.rcuniverse.com/forum/m_8479610/anchors_8479610/mpage_1/key_/anchor/tm.htm#8479610[/link] a good discription is in it somewere, but I didn't locate the exact post.
But a better way is described in this thread around post 82 [link]http://www.rcuniverse.com/forum/m_6948801/mpage_4/key_/tm.htm[/link]
These folks have said it better than I can

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Thanks for your reply. Lots of info in those threads.
Capt. Buford

NM2K

My Feedback: (14)

The 11x8 is my favorite break-in prop for the G90, but a 12 or 13 x 7 or 8 is just fine too. The latter group are fine for flying too. You want to stay away from a 14x6 unless your scale model is capable of very slow flight, like a Cub or something similar.

Keep in mind that any .90 that was derived from a .60 crankcase, is not going to generate as much horsepower as the original OS .90FSR and Webra .90 two-stroke engines of years ago. I wouldn't expect the latest generations of OS and Super Tigre 15cc engines to swing the big lumber as the two older, fully sized crankcase editions of these engines. That's what happens when you increase the bore, but not the crankcase/induction runs of the engine. If you really need to swing lumber that large, you should consider a 1.08 or a 1.20 sized engine.


Ed Cregger

rc34074

My Feedback: (5)

If you want to fly 60 size warbirds at speed I would recommend the APC 14-6 prop. I have used the g90 on my 60 size warbirds for a lot of years and the g90 turns this prop VERY WELL. After breakin I get 10,500 to 10,800 on the ground and it unloads noticeably in the air - probably close to 1000 rpm. I get great strafing runs and large circular loops with this setup on my mustangs.

I have flown the previous version of the H9 60 size and now have the World models 60 size mustangs and this prop engine combo is great for those planes. It also flew my Top Flite 60 size mustang and P47 very well, although the best 2 stroke engine for the Top Flite 60 size p47 was/is the Super Tigre 2300 - it flies this plane like a fighter - loved that combo .

The rpms I list above are what I get after breakin. I use 10% Omega fuel.

My mustangs certainly don't fly like cubs - unless the cub has a ys120 in it! If they did I would put a different engine in it. Any g90 that flies that poorly is either worn out or VERY poorly tuned.

Ed

mr.scale

My Feedback: (4)

ok, the prop is going in to a nitroplanes extra 63"..
it calls for a 70 to 90 4c..and i got a 52xls and a ringed with a apc11x7 on it but it feels heavy!!!!

FLYINGFOOL*2007

All, If you want to hone the cylinder out on your engine and refresh it with a new ring, I have a tool that makes this very easy,
go to your local parts house (Napa, Auto zone, Ect.) and purchase a brake cylinder hone, they will not have a pressure point during the prosses and that is very important to keep the cylinder perfectly round and get even crosshatch pattern and they will not "dig out" the cylinder wall at the intake/exaust ports, stones are available to 600.


Flt it like it aint yours![>:]

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Very good info.

I have a question. Could the hone be used to clean up an the inside of the ABC cylinder liner? The engine has no piston ring.
The engine is an O.S. .32 ABC that bogs down once it is in the air. I have replaced the 2 bearings. The rear bearing was bad.
The flying field engine Guru says I need to clean up the inside of the ABC cylinder liner and also the outside of the piston. He thinks that crap has built up on both the piston and liner and that is why the engine bogs down once in the air. Also if this is true what could be used to clean up the outside of the piston?
The engine has great compression and the new bearing feel fine.
Capt. Buford

JNorton

My Feedback: (2)

Do not hone an ABC engine. You'll remove the top squish band. The cylinders are not parallel but narrow at the top.
John

FLYINGFOOL*2007

JNorton is correct, DO NOT hone a ringless liner, To clean it I would use crocus cloth or polishing cloth and marvel mystery oil and some eblow grease, Same for the piston. this particular type of engine has a tapered liner and you would change this with the hone.



Fly it like it ain't yours![>:]

[email protected]

Thanks once again to you 2 gentlemen.
Capt. Buford

FLYINGFOOL*2007

Happy to help.

rc34074

My Feedback: (5)

How much does the extra weigh ready to fly? to 3d you generally will need an engine at the top end of the recommended range, but if the plane is built too heavy you still may not be able to 3d even then.

I haven't flown the 52xls but its smaller than the lowest size engine they recommend, which is probably why you are considering the g90. Do you have a g90? Or are you thinking of buying an engine to replace the 52xls?

Ed

coachdavis10

Okay, I have talked to several people (including one on here) who have been extremely helpful. Let me have some opinions. Supertigre 4500 on FAI fuel???? should I add castor? Run it as is? I have a 22X8 on it right now. Stock carb. Thanks guys>>>

fujiman

My Feedback: (133)

some fuel companies have super tigre big eng. fuels with lower amounts of oil. if i remember it is like 12% (someone correct me if i'm wrong) i like to have SOME caster in the mix. w/12% i would like to have 50/50 cast. syn. the rest alky. i have installed an extra head shim so i can run 5% or 10% nitro. this seems to make my big tigers happy, no flame outs and the needle has broader adjustment range. hope this helps. just remember the more castor the more carbon/gum or varish buildup on piston and in the combustion chamber and exhaust ports. could cut the castor back to 10/90% and you still will be safe. also if you choose the run 100% syn. just make sure to run the eng a little richer to be safer against lean runs at the end of the tank. i'm currantly modifying my 4500 so i can run a walbro wt-499 alky carb (have trim some cyl. fins on the back of eng. to clear carb). anyone out there running a walbro alky carb on their 4500's?????? some input would be great!!!!!!!

qldviking

I have 4 ST-4500's I run them all on home brewed feul, 15% mix of castor and synthetics, rest methanol. I have found after testing that the little gained by adding nitro isnt worth the extra cost. I have tried the walbro carb, but found it didnt perform any better than the standard set up by much at all, if I remember rightly I gained maybe 50rpm. These big tigres take some setting up and running in, but done correctly they are very reliable and solid motors

fujiman

My Feedback: (133)

i went with the walbro mainly for the pump. this carb is used on zenoah alky engs. using the walbro allows you to put the rather large tank needed on or very close to the cg of plane. plus does away with the change in mixture from full to empty tank and or position off plane, climbing/diving, etc. that's just somethings i have found.[8D]