Lencho

A friend of mine has a new 3W 100 B2 engine on a 1/3 scale Sukhoi from H9. We flew the plane last Saturday and sufferded three dead stick landings, the maden flight lasted less than one lap because the engine died when the thtottle was mooved from 1/2 to 1/3 for the aproach. We proceeded to richen the high needle valve one complete turn and took off, this time the engine performed better so we proceeded to fly for 8 min, after a complete check up of the plane, of course. This time the engine quited again on aproach at 1/3 throttle. We decided to remove the cowl and changed the prop from a wooden 28-10 3W to a Mejzlik 26-10 composite suspecting overheating. Took of again and the engine began to stutter almost as soon as it took of, so we decided to land again and this time the engine did not quit, closed the high needle again 1/4 turn and took off again, the engine improoved a little but stuttered again so we repeated the same procedure and took of again, this time it was good to go and flew for about 6 more minutes, then it quited again at 1/2 throttle. After al this we decided to call it quits to avoid any damage to the plane or further mishaps.

The engine was borken in on a Giant Sudokhoi from Morris and we must have used around 2 galons of fuel with a mixture of arround 32:1 Gas:Zenoah oil on it. The engine never quited and worked OK always when on the Morris.

For the H9 Sukhoi we changed the fuel mixture to 40:1 and that was all the changes we did to it.

None of us at our field has any experience with gassers much less such as a 3W engine or such a big plane so I think we are making some kind of mistake regarding the set up of either the fuel tank or the ventilation of the cowl.

It is important to add also that the engine tried to quit when inverted and on Knife Edge flight

The owner speared no expense for this beauty an it has top of the line Futaba servos, two PCM receivers, three 2000 Mah NiM bateries, including one for ignition and a 280 oz. torque Multy plex Giant Servo for Rudder.

Please Give your advise because we want to keep and enjoy our US$4,500.00 investment.

Thank you very much in advance.

Lencho.

rcflyguy_26

My Feedback: (8)

You should be at 50:1 on your mixture. What oil are you using? 32:1 is way too much oil for a 3w.

You said a full turn adjustment? If it was still at factory setting you should only move it 1/8 to 1/16th of a turn at a time, they are very sensitive.

The best way that I have found to tune a twin is by temp. I run mine at 180-195 deg at the head of the cylinder. Too much higher your lean, lower too rich. Now cutting out from 1/2 to 1/3 sounds like too lean of a low end mixture. Without hearing it that is.

Do you have any baffling?

Can the small hole on the carb plate receive direct air in flight? This hole is on the pump side of the carb.

Check this stuff out and get back with me. You can e-mail me and I'll give you my phone # It may be simpler that way. rcflyguy@ yahoo.com

Later, Scott

Tim Redelman

My Feedback: (36)

Take a close look at your fuel system as this seems to be the only variable in the system other than the oil%. I wouldn't think it would make that much difference. Could be pin holes , a line unhooked in the tank got me once. I took off flew around for a little while and then problems started. These things seem obvious but even the best of us screw up sometimes.

Also check the carb for dirt sometimes picked up from a new fuel system, or from the switch from the old system. Hope this helps.

Tim Redelman

3dbatixkid

wrong oil dude. Gotta run amsoil or the cactus oil. I found out the REALLY hard way.

Torque'n

You need to run a 50:1 oil or higher. You might have a fouled plug so check them out. Also if the engine was running great on the plane it was in before that pretty much counts out the engine as being the problem. First thing I would do it make sure you have a plate that covers the hole on the carb. That hole goes to a diaphram that hooks to a fulcrum arm. If air hits that direct then it will hold it shut allowing no fuel to be pumped into the carb. Second if that is already done I would go threw the tank and make sure the plumbing is ok. If you cranked out the needle one full turn and it still ran fine then it sounds like you have a tank that is suffering to deliver fuel. It only takes 1/16 to 1/8 of a turn to make a big difference. The way you said the engine tries to die while inverted or knife edge, what did it sound like? Did it go extremely rich? If it went rich then I can bet there is not a cover over the carb hole. If it went lean then I think the clunk is not getting into the fuel in the tank. Try some of this stuff out. The oil you should be using is 50:1 bellray, 50:1 amsoil, 50:1 redline, 50:1 Cactus Aviation oil, Honda hp2. There are other oils out there but those are the most common. So to sum it up. Check your plugs for carbon, make sure there is a plate over the carb hole (or get a 90 deg intake from Cactus Aviation), and make sure the plumbing is correct. I have a feeling it is the carb hole not being covered. Hope this helps out a little.
Garrett Morrison.
P.S. if you have anymore questions you can reach me at [email protected] and I see what else I can help you with.

mglavin

My Feedback: (31)

You can use any two-stoke oil in your engine, period.... There are differences in the quality and composition of various oil brands and types.

I'd use a petroleum based, ash-less is preferred for at least 6-10 gallons of fuel with this engine. After the break-in period use a quality synthetic oil.

Oil manufacturer's design their specific oil to be used within given parameters. That said, mix the oil according to the recommendations on the label of the oil you are using... Arbitrary mixtures based on other types and brands of oil SPELL premature failure...

Your needle valves settings should be within given standards. If your all over the place your [one turn in either direction is a lot and would be considerable abnormal] typical settings for your engine would be 1-1/2 on high-needle and 1-1/2 on the low-needle, to start with.

Some 3W engines have had problems with the carb block adapter/manifold. The phenolic material utilized is prone to warp with heat. Best fix is to remove the block and verify that its perfectly flat and or true. Resurface if need be, with progressively finer sandpaper. Reinstall the block and try again.

There is a screen/filter within the carb, easy to check.

Check for loose bolts regularly.

Do you have large exit hole for air outlet. Typical suggestion is 3:1 ratio for outlet verses inlet. On the Sukhoi this is tough, I'd suggest baffling the engine for best results.

Venting the carb/fuel pump diaphragm is considered routine. A fuel line with a hose barb attached to the back of the diaphragm plate is easy to do and can be vented inside the fuse or 3W offers a snorkel type carb inlet venturi adapter with provisions for equalizing the air seen by the diaphragm.

The smaller prop is better for the break-in period

Verify the tank pickup and plumbing are sound and properly installed.

You mentioned NiMh battery packs, these are fine but you should cycle them at least three times prior to use as they will not reach capacity until they've been exercised. Verify they are providing at least rated capacity before use.

If all else fails remove the engine and send it for a check-up, better safe than sorry. Also contact the Cactus or Aircraft International for help with your engine, either will be glad to provide assistance.

Have Fun

bob_nj

My Feedback: (62)

Always a good job from you man! You must have way too much time on your hands Happy Holidays_bob

Diablo-RCU

My Feedback: (1)

One comment on the oil. I have been using Honda HP2 at 32:1 in a 3W-100. It did not require any change of the needle settings and the engine runs just fine. I know 3W recommends a leaner oil ratio with synthetic, but the Honda oil was designed for a 32:1 ratio without carboning up the motor. More oil = better protection and more power.

Lencho

Thank you guys very much for your quick response, it seems like We will be able to fly this plane as soon as this Saturday or Sunday, in fact all of your tips are right on because we did miss out on the complete set up of the fuel system and carb.

Happy Holidays to all of you and your families and I´ll keep you posted next week end.

Saludos,

Lencho.

DMcQuinn

My Feedback: (13)

You said the engine quits when inverted. If it quits immediately when inverted it is probably air hitting directly the carburetor regulator inlet. If you fly inverted for a few seconds, then it may be in the fuel tank (clunk stuck in front of tank).
Even when the clunk is stuck in the front of the tank, it takes a few seconds or more for the engine to draw all of the fuel out of the tubing. My 3W engine gurgles and sputters at 1/3 throttle when I roll inverted, but it is not the tank -- it happens too quickly. I believe it is the changes in air pressure in the cowl.

fancman

My Feedback: (16)

Hi
The entire problem with your engine as I see it is that nobody in your area knows much about the care and feeding of a gas engine. I hope you will take the opportunity to read some fo the many engine articles on gas engines and learn all there is to learn about them before you accidently ruin a great engine. Judgine from your comments there is no way you should do anything to the carburator of your engine at this point. I would suggest you find a local lawn mower/weed eater repair shop in your area and inquire about gas engines there for a start. In this hobbby you will find there are hundreds of ways to skin a cat but the best way is for you to learn everything you can about the subject and make your own decisions based on all the knowledge you gain from your reasearch.

Your engine is not nearly broken in at this point but shoudn't stall if the carb is set properly no matter what the oil mix. More oil will eventually foul your plug but you won't burn up your engine at easily while you learn. A lean run however will burn your engine up no matter what the oil mix. That's an expensive engine. Take a few hours and read all you can find about gas engines and enjoy your engine for a long, long time. Trust me on one thing.....you don't want to have to send that engine back for new pistons and cylinders.

Good luck

Mervin Jones

pyb33

Did you change the position of the carburator by any chance ??
Did you inverted it ???