squeaky penguin

Hi,

I've got an SPE 43 thats only pulling 7,000rpm and I assume that it is good for more then that. To start off, this is my first gasser, and I've had no problem starting it or keeping it running. I running a Zinger 18x10 and currently 45:1. It was 30:1 for the first couple gallons. I'm really not sure how to get more rpm out of it so let me give you the details and ask some quesitons:

It's only had about three gallons through it - does it need more before it really opens up?
I fly at 7,000' - is this having a large effect on it? I don't notice it all that much with glow enignes.
I've guessed and checked timing it - the most rpm I could pull was with the timing almost completly retarded - is this normal for this engine?
I am about to try a new spark plug, it was on its second, and is moderatly fouled up - would that make that much differnce?

I can't think of anyting else right now. Any tips, questions, suggestions, I would very much appreciate any help.

soarrich

My Feedback: (98)

This is what the guy that imports them said they turn:

JXF Wood props => RPM

18 x 6 => 8,100

18 x 10 => 7,350

19 x 8 => 7,450

19 x 12 => 6,500

20 x 10 => 6,300

21 x 8 => 6,430

These are fairly conservative numbers we got from testing.

karolh

Three gallons is a fair amount of running on an engine which should loosen it up quite a bit but you are not doing it any favours if it's all bench run and not in a model flying. Considering your altitude your engine is running in the rpm ball park but I suggest that you try a lighter loaded prop like a 18x6 or 18x8 to get the rpm up. If the plug shows signs of being fouled that a fairly good indicator that you are running the engine too rich. You should use a degree wheel to properly check the timing, and if you don't have one you can download one off the CH Ignitions site which also gives a step by step method of how to check ignition timing which should be set at between 28 and 30 deg.

Karol

soarrich

My Feedback: (98)

Get Pennzoil run it at 32:1 all the time.

Three gallons it's run in enough, in the plane is better.

7000' might cost you that much in rpm over what was listed, that's normal with gas, nitro engines are supplying their own oxidizer, nitro was invented as a monopellent rocket fuel.

Do check the timing, here's my way:
The easy no math timing.

Cut a strip of paper 1/4" x 5".

Rap the paper around the prop drive, back by the crankcase where the magnet is. Overlap the paper then cut with a #11 blade cut though both layers of the paper.

Now you have a piece of paper the exact circumference of the prop drive.

Cut it in half, take one of the halves and cut that in half again, take that and cut it in half also. Now cut it so it's in 1/3 and 2/3 pieces.

The 2/3 piece is how much before TDC the engine should fire, (30*).

Now find TDC by removing the spark plug, then sticking something in the hole, a pencil works fine. Move the crankshaft until the piston. is at the top of the cylinder, you'll find that about 5* either side of the TDC it doesn't feel like the piston is moving. Wiggle the crank back and forth until you can find the center of this piston not moving zone, that's TDC.

Now with a marker make a line across the edge of the prop drive onto the crankcase, it doesn't matter where, just that it's easy to see.

Now turn the prop drive clockwise a distance equal to the 2/3 piece of paper.

Plug the ignition into a 4.8v battery, and turn it on.

Now with the two screws loosened move the sensor off the magnet until you hear the ignition pop.

Tighten the screws for the sensor down, then confirm that the timing is still set that 2/3 piece of paper before the TDC mark.

You may have to lengthen one of the grooves in the sensor mount to get the timing correct.

pe reivers

Good post Rich.

@ Penguin,

The fact that you had to change fouled plugs, points into the direction of a severely rich carb setting. There is where your lost 350 rpm probably are hiding.

squeaky penguin

Here's a pic of the plug. Trying to get more rpm, I leaned out the settings, which has helped, but it didn't run very long at those settings on this plug. I've got a new plug in, and will give that a try. I will also to time it in the correct manner, and we'll see where it will be after that.

pe reivers

The setting now looks a bit lean, and the plug gap seems too small. Set the gap to at least 0.5mm (0.020"" )
Try a NGK BPM6Y plug

squeaky penguin

soarrich,

I used your method of timing and either I found my problem, or I'm somehow srewing it up. On the picture the top line is TDC, and the one below it is the 2/3 piece or 30 degrees. The lowest line, where it's set at in the picture, is where is firing. This is with the timing set as late as it can be. Can anyone explain this?

soarrich

My Feedback: (98)

It looks like it's very advanced. I don't know why, but the Chinese seem incapable of timing an engine correctly. I have ALL the MT line, that's out, and the timing was wrong on all of them, I just bought two Turngiy 26cc and the one with a working sensor was timed incorrectly, all the GR Pro engines where timed incorrectly. As to explaining it, I can only say it's Chinese.

The good thing is there are many fixes for it, but the easiest is to take the screws out of the sensor mount. Get some GOOP or RTV and put s smear of it on the crankcase where the mount would be if you have it timed correctly, put the mount in the GOOP, then take a zip tie and go around the crankcase and over the sensor mount. I did this on my first Ryobi conversion and two other engines since then, it works fine.

On my MT42 the 2/3 slip of paper worked out to be about .310".
The math is 3.1416 x the diameter of the part with the magnet / 12

soarrich

My Feedback: (98)

It also looks like you sensor is rubbing, not good. If it's rubbing all the way around you want to shim it out with some card stock, if it's just on one part something is out of round or out of balance.

squeaky penguin

Well, I used the RTV and a zip tie to get the timing set to 30 degrees. I wasn't able to tach it because it's raining and I ran it in my garage, but it was clearly running way better. It started eaisiery, ran smoother, and sounded better. I assuming it pulled more RPM as well.

Thanks to all who helped, I'll report when I can get it tached on how much RPM I gained.

squeaky penguin

soarrich,

I did look into the sensor rubbing, and it was rubbing all the way around. I made sure when I remounted it that it isn't touching.

john911

My Feedback: (1)

i have a spe43 i get 7300rpm with 20/8 prop i think that all your going to get from this motor.

squeaky penguin

Well, I got the engine running again, and while its running much better, it's not pulling anymore RPM. Should I still try a hotter plug and a lighter loaded prop? I'm just hoping I don't feel the need to get a bigger engine.

soarrich

My Feedback: (98)

With your altitude that may be all the rpms you'll get. What size and weight airplane is it in?

squeaky penguin

I haven't weighed it yet, but its in a GP 27% Edge 540. I bought the engine from Peakmodel when I got their 71" Yak, which weighed a lot less, but it crashed due to me being stupid and having the reciever pack die on me. I wouldn't have bought the Edge, but a guy was selling it brand new for cheap very close to me. I've flown it a couple times and its seemed fairly underpowered, I might have to be looking in to a DL.

soarrich

My Feedback: (98)

My friend flies a GP Sukhoi that's about 27% using a G-38. The 38 seems to haul the plane around well so you 43 should do OK. The DL50 will definitely overpower a 27%er, but you might like that, it's a good engine.

octanehuffer

The problem is the altitude.

Pablo Azcobar

<div style="border-bottom: medium none; text-align: left; border-left: medium none; background-color: transparent; color: #000000; overflow: hidden; border-top: medium none; border-right: medium none; text-decoration: none">Cut it in half, take one of the halves and cut that in half again, take that and cut it in half also. Now cut it so it's in 1/3 and 2/3 pieces.

The 2/3 piece is how much before TDC the engine should fire, (30*).

Thanks for the tip!

I have had my SPE 43 for months and don't fly it often as Icouldn't get it to run right in midrange, Ialways had a misfire.

Ireplaced the Melody Ignition with an RCEXL ignition for a DLE55, and had to swap the plug boots, and re-installed the resistor that came with the RCEXL. Ialso soldered all connections.

After this, I still had that bad misfire.. Sparkplug is Champion gapped at 0.020"

I followed your tip, but what I did was Cut it in half (180degrees), take one of the halves and cut that in half again (90degrees), and cut that into 2/3(60) and 1/3 (30degrees). I used the 1/3 this time.

Ihave yet to tach this as I finished at night, but she runs like a dream now.

I run this in a 28% Cermark Edge 540 with a Hawk 20x8 wooden prop.

Great post!!!



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