RoysterDW

Hitech sounds good. Will I need the extra long servo arms for the Hitech servos?

Got the prop sizes on my wishlist at Tower

RoysterDW

What are the steps in starting a brand new gas engine?

...and should be put on a test stand first?

[8D]

pianori

My Feedback: (2)

I personally bolted it on a test stand first so that I can control the conditions of the braking in process. Some people suggest braking in the engine in flight. That is fine I guess the problem is that if you do not set the engine right as far as the mixture you are running the risk of having the engine run lean or rich while in flight. The way I see it especially for someone that is new to gasoline engines (since there is a learning curve) is to run the engine on the bench first for about a gallon. I Personally would run the engine ten minutes on the test stand from low to medium idle and then for ten seconds at full throttle. Then shut the engine off and let it cool to environment temperature. Repeat the process three times. After that I set the engine at a rich setting and let it run at about 2500 to 3000 rpm for an hour (usually about 50 oz of fuel); repeat the process for 1/2 a gallon then start to lean the high end needle valve. Once you will burn close to the full gallon you should notice about 100 to 200 rpm increase from the top end. This happens as the rings of the piston sit in and make a better seal with the sleeve.

After the engine is about broken in and I am completely happy about the performance as well as I understand exactly how to set the engine I then install it on the model. After the first gallon the engine is typically broken in about 85 to 90 %. The complete break in will happen around the fifth gallon through the engine but you do not have to wait for that to happen on the bench. Fly the next 2 gallons slightly rich and then you can start to lean it more. I have used fully synthetic oil for the complete braking in process (except for the first gallon on the bench which I used regular lawnmore oil from my local Home Depot store) . After that I used Klotz oil which I still use today. It is an excellent oil that leaves no residue and it burns clean. For the first two gallons I used 30:1 oil mix and now I use 45:1. Some people believe that you do not need to use synthetic since these engines are heavy duty industrial engines converted for RC use. My opinion is that a good synthetic provides a low friction environment for the engine which means a lower temperature which translates to a slightly thicker oil state (higher viscosity). This translates to more power due to better seal on the rings and less wear on the engine components. I personally run two gallons on the bench, but that was because I was testing the engine with different components while trying to make it better. You will find that your carburetor settings will slightly change from switching from a non synthetic mix of 30:1 to a synthetic mix of 45:1. With that in mind it is better to understand the difference and how to set it right. Again this is my personal preference and opinion. Some people put it on the plane and go fly it. That does not work for me as I want to understand the engine before I let it loose up in the air. You are going to decide what works for you best. If you have any other questions let me know.


I hope this helps

pianori

My Feedback: (2)

As far as the steps look at this manual

[link]http://www.himodel.com/en/info/manual/SPE-40CC_manual.pdf[/link]

grossy2

Hi Guys,

I have this Engine also and have a problem you may be able to help me out with?
I tune it to run sweet on the ground, but as soon as you take off it goes rich.
I land lean it out a little at a time so its running sweet in the air, but then Its to lean on the ground and can not get full power.
Would a velocity stack fix this, for with airspeed over the carb intake, would it cause it to lean out.
Also it pops and farts at mid throttle range, would this also be cause by the mixture changing in flight.

Cheers
Grossy

pianori

My Feedback: (2)

Your engine is running rich and lean because you have an issue with the diaphragm of the carburetor. I bet if you fly the plane without the cowling your problem will go away. When you will re-install the cowl back on the plane your problem will re-appear. This happens because in your particular case the cowling is not allowing the air to flow freely inside the engine compartment. As the engine operates while the airplane is in motion, there forms a pressure drop inside of the engine cowling area. The pressure drop forces the diaphragm of the carburetor to work inconsistent. This is a common issue with some setups. The remedy to your problem is to provide a consistent ambient pressure to the carburetor pump. The best way to fix this is to solder a small brass tube in the back of the carburetor plate where the diaphragm pump hole is (on the back plate) and connect a tube line to a different location where the surrounding air and pressure is consistent. You can find consistent undisturbed air behind the fire wall of your engine. So drill a small hole (the diameter of the tube) on your fire wall and insert the tube line that is connected to the back plate of the carburetor (the one that you will solder). This will solve your lean- rich run issues. As far as the mid range popping and gargle sounds those are somewhat normal if you are using the SPE Melody ignition. It is not that great of an ignition. You can set it to the point that it will almost run right but you will always get some popping sounds in the mid range. If you want to get rid of the popping sounds as well as have an impeccable mid range transition and increase some of your top end power get another ignition such as a CH, or an RCexl. You will notice a big difference. The velocity stack will not help much in smoothing the engine but it will capture the spilled out fuel out of the carburetor due to harmonic vibrations caused after certain rpm. I have a velocity stack at my engine and now it runs without fuel spraying out of the carburetor. I hope this helps.
Take care.
Eric
[img][/img]

grossy2

Sorry to mention that I was flying with out a cowl for tunning, but I will give the static port tube a go. I was also getting residual fuel on the wing, so I hope the velocity stack will fix this, I just ordered 1 from Tower.

I had it in a 25% Edge, but due to a Aileron servo failure its no more. I have just ordered a 25% Extra 260 (ARF Brand) that I will be putting it in. More pwer than required, but you need power to have fun and you can allways throttle back.

The CDI I will live with. For I dont know about the rest of you guys, but I hate having to spend extra money to get something to work wright. It should come out the box ready to go and not have to Mod to get it to perform ok.

This is why I switched to Gas, reliability and not having to play with mixtures all the time.

Keep you posted as to how I went.

Where can you get the new inproved 42cc?

Cheers
Grossy

pianori

My Feedback: (2)

Well I guess I was presumptuss as far as the cowling. It is not a bad idea to give it a try for the static port tube. See also if your carburetor is siting properly or that is not loose. Also remove the Back plate where the pump is and check for any dirt deposits in the little mesh filter inside the carb. One of those things most likely should take care of the problem.
As far as the engine you are right unfortunately it is not maximized for power as it is offered from China, you have to make some changes to make it work well. I believe the new version of the SPE will address some of those issues. I believe they have already changed to a new ignition so it should run better. Any way, BCMAengines.com and coperheadaviation.com are selling an excellent ignitions for $70. It will transform your engine. It is more money, but whenever you are ready it is a good investment trust me I have done it myself and I cannot be happier. See the link of my engine turning a 20X8 at 7500 rpm
[link]http://www.youtube.com/profile?user=pianori[/link]
Take care

XJet

Look at the bottom of your carby -- you'll see a plate held on with four screws that has a circular shape pressed into it and a small hole on the edge of that circle.

Chances are that on your engine, the hole is facing into (or almost into) the slipstream from the prop.

Carefully take the plate off and rotate it so the hole is facing to the rear of the plane (firewall).

What happens with the SPE engines is that propwash blows into this hole and upsets the diaphram which controls the engine mixture.

Because it sees increased pressure (from the static head created by the airflow), the carb things "oh, more air pressure, I'd better richen the mixture" and promptly does so -- which makes your engine run really crappy.

Turn the plate around so the hole faces to the rear and this won't happen.

Some folks go to all the trouble of soldering or brazing a little tube onto this plate then running a plastic tube back into the fusealge but 99% of the time you don't need go to these lengths (and sometimes that 'll actually make matters worse). It'll take about 1 minute to swing that plate around -- give it a go and report back.

pianori

My Feedback: (2)

grossy2 give it a try like Xjet2 says it might take care of your problem. Test it with the cowling on and off and see what happens. You can always braze the tube on the plate if it does not work. I have not heard of any case where someone had an issue or problems with brazing a tube in the back of the plate, unless they did not do a good job baizing the tube, or use smaller diameter tube than the diameter of the hole on the plate. Any way, it does not matter, if what Xjet suggests works obviously do that. If not do some soldering (or brazing).

pianori

My Feedback: (2)

I am getting both a 42cc and a 50cc from China next week in. I will test both engines in an attempt to see if I can make them better, or to see how reliable they are. I will be checking for vibrations, crank shaft balancing, check low rpm & high, midrange transition, the ignition system, the carburetor, muffler quality, casting quality, parts and support available etc. I will be doing a full evaluation. Once I figure all the bugs out and ways to improve it there is a chance that I might import them and rep them. I am working on this now as we speak.

grossy2

Thanks for all the help guys. Ill let yoy know how I went when I get the Extra built.

Cheers
Grossy

RoysterDW

Look forward to hearing more from you!

I am about to order some bits from BCMA for my SPE40 such as pitts style muffler, anti-vibration mount, rings and a prop.

RoysterDW

Hey Grossy

Mate let me know how you go with the build on the Extra!

I have just started mine, epoxy coating internal and CA hinges in wings and stab. Going with the 2 x servos in the tail for the elevator and of course the pull-pull on the rudder. Not sure which servos yet but have a mate who researching it for me. Probably be carbonite type Hitech servos. I kinda like to do my builds when I have everything so I can pre check stuff.
Also have another switch and batteries to buy. Most likley be a small LiPo for internal batts to save weight.

XJet

If we're talking 40cc gasser here then forget they karbonite servos -- they'll strip on you, probably with disastrous results.

Karbonite is a great low-wear alternative to nylon but you shouldn't use them anywhere that nylon would not also be practical -- and nobody with any sense uses nylon in a 40cc gasser setup.

The problem with Karbonite is that it's very very brittle. Sure, it's strong if you apply a fairly constant load (just like it's hard to break glass by applying a steady force) but if you subject it to vibration or shock-loads then (just like glass) it can be shattered with surprisingly little force. Having big 3D surfaces will also make matters worse -- if there's the merest hint of flutter those gears will be gone in the blink of an eye.

I would strongly recommend using metal-geared servos in any gasser -- they're really the only option if you're using standard-sized units.

RoysterDW

Point taken Thanks for your post.

Metal gears it is!

Can you suggest a Futaba or Hitech servos for the job?

N.B. Mainly those brands as I have vouchers for Tower Hobbies [8D]

grossy2

Hi Royster,
Thats good advise from Xjet, use metal.

I will be using Hitec 625 mg on Elev (1 for each side) and 645 mg on Ail. I will be using a 13kg Tower pro mg on the Rudder (Pull Pull system), for throttle just a 311 nylon.
The Elev servos I will put in a spacer so they fit in the wright position, for with the servos at different hights the elev movement will be different due to different angles of the control rods.
I can not afford Digitals. Use a 6V pack on the radio side and a 4.8 on the engine all Nickel Metal.
I will also be adding CA hinges with some extra Great planes ones. especally at the tips of the ail. With a Gas engine you get a lot more vibration so things crack and vibrate loose. I forgot to mention use lock tight on everything.

With the Engine I will be adding a Velocity Stack to try and fix the engine going rich in flight. I plan to swing a Hawk 20X8 prop. Fuel is 40:1 synthic. Also you may have to lock wire the spark plug cap on, for mine keep falling off.

Just make sure you use Nylon clevis and push rods with the engine and keep the engine electrics and the avonics electrics as far away from each other as possable.
This will minimise the chance of RF interferance.

Hope this gives some ideas.

Cheers
Grossy

RoysterDW

Thanks Grossy

Where are you geting your Hitech servos from? Tried a search at Tower and they dont have them.

Also where did you get your velocity stack from? I am trying to get one through BCMA engines along with a isolation mount and pitts style muffler.

Cheers mate

XJet

I hate to rain on your party again but if that's a Tower Pro MG995 you're planning to use on your rudder then *don't* -- these servos are for buggies, *not* for valuable gas-powered model airplanes!

Not only do they suffer friom awful overshoot, the pots wear out real quick and some also have a tendency to just stop working without warning.

I had a failure rate of around 30% of the first batch I bought.

They're fine if you want a good strong servo on something that (at worst) will just go round and round in circles if/when it fails -- but for planes -- use something better!

grossy2

Thanks for the heads up Xjet.

Check out these stock # at Tower; GP Velocity Stack LXJ775, HS-625MG LXUZ87, HS-645MG LXUZ89 and you mite want to look at these switch's, EMS Heavy duty DSC switch LXONU3.

Dont forget the Tygon fuel tubing, Gas stopper for tank and neoprene tubing for in the tank (Remains flexable).

Grossy

RoysterDW

Hows the engine testing going?

bjor

Hi Royster. You will love the SPE 40. I ordered one off ebay a few weeks ago to put in a CMP Yak 54. The engine is great with the walbro carb set up. Mine started straight from the box with a 30:1 mix and have since changed to a 40:1 mix with great results. I ran about 2 litres through the engine on the ground before first flight. The initial maiden had the engine "popping" but it gets better and better every flight - just run it rich to start and lean out a bit each flight. I have a 4.8V 2500mah sub C pack on the ignition - works fine with plenty of flying time. Also - make sure the plug cap is fixed firmly on the plug. Mine kept falling off until some tight fisted bloke shoved it all the way on properly - hasn't fallen off since. The only problem - my standard side sounded muffler fell of in flight so now I'm waiting to order a new one. USE LOCK TIGHT as already suggested by grossy. I'm also changing to a Hitec 645MG servo for the elevator - don't want to rick the nylon gear ones. Best of all - $1.20 a litre to run. Now I can fly all day without having to folk out a fortune for nitro.

RoysterDW

Great! Many thanks bjor!

Which club do you fly at? I fly at TMAC and have just joined Sun Coast Flyers up at Coolum where they just had the DA Challenge.

What 2stroke oil are you using? I will have to get to explain how to mix it in as the 40:1 ratio I dont understand

What kind of prop are you using too?

Sorry lots of questions

Pm me if you want my moby

bjor

Royster. I fly at PRAMs on the northside. Started about a year ago with my 13 year old son, got the bug and it keeps getting bigger. I went from a 40size, to a 60, to a 120FS and now 40cc Gas. I plan to get a 28 - 30% extra next - maybe next year. Coolum is the best club - I'm so jealous. I was there on the weekend watching the D.A challenge. If I could fly 1/10th as good as those blokes I'id be happy. I'm using a 2 stroke mix I purchased from Stihl - Its a really good high quality blend. The break-in should be at 30:1, i.e for each 5 litres add 166 ml of 2 stroke oil, for 40:1 add 125 ml and 50:1 add 100ml etc.
I'm using an ASP 18 x 8 prop at the moment but I will go to a 20 x 8 after breakin. Don't worry about the questions - I'm learning as well.

RoysterDW

Yeah we started in Jan this year and have the same disease as you. My son is 9yrs and is loving it. Dont see us getting a Comp ARF for a while yet as thats mega bucks with a close to a grand just for servos. Hate to bin one of those birds. We still have a passion for electric as well and fly with friends in parks. Latest edition is the FuntanaX.

As far oil I was going to use what BCMA recommended (Penzoil for air cooled engines) or maybe even some Motorex or Motul that I used to use in performance 2 stroke motocross dirt bikes.

We went to prams for the S&B day. Zac won the limbo comp and Best Young Ace, very nice field but yeah Coolum is really nice. Hope to do our gold wings up there.

Thanks for the tip on oil ratios.