Pterodactyl PTE50i
Displacement: 50.8cc
Bore x Stroke: 43mm
Carburetor: Walbro pump
Bearings: NSK Japan
CDI: PTE auto advance. 4.8v-7.2v
Max. Output: 5.3 h.p 7500rmp
RPM Range: 1300-8000rpm
Weight incl muffler, CDI & standoffs:  1740g
Fuel mixture: 25-40 : 1 mineral oil for running in.
Propeller: 22X8, 22X10, 23X8, 24X6 (2-blade prop.)
Spark plug: CM-6 equivalent. Iridium electrode for hotter spark.
12 months Australian guarantee on engine and CDI
Carbon fiber reed valves

FREE Prop drilling jig included
The PTE50i is a very reliable high power engine designed to be used in all modern 50cc models. Crankcase is 6061 aircraft grade aluminium. Crankshaft bearings are by NSK Japan. Carb is a Walbro Japan not a Chinese copy. Prop bolt pattern is the same as the DLE50, DA50R.
Muffler mount is the same as the DLE50, DA50R, GP50R.
Engine comes with Australian instructions and a firewall drilling template.
CDI is by the industry standard latest Rcexel with tacho lead.
All engines test run for 30 minutes for quality assurance and to set tuning.
12 Months Australian warranty, carried out in Australia, not China.
Special introduction price with free registered post
Custom machined standoff lengths to your specs $38 FREE REG post
Dealer enquiries welcome.
Prop driling jig
We are so confident in these engines that we are giving a money back guarantee on the engine. If it does not live up to expectations simply return it to us for a full refund on the engine. It must be in as new condition, not damaged in any way.
All parts carried in stock
We tested these engines rigorously for two months before releasing them on the Australian market. They performed excellently. Very reliable, high power and easy starting. PERFECT. Revs when run-in are 7200 on a Hawk 22x8 C-1 prop & 7000 on a Hawk C-1 23x8.
The PTE50i in my personal plane, Sbach 342, is now fully run-in and is doing 7400rpm, so i'll be moving up to a 23x8 Hawk prop.
Distance from the face of the prop hub to the back of the standoffs is 170mm
ENGINE REVIEW.    By  BRIAN WINCH as appeared in the Airborne magazine

CONFIGURATION                 Two stroke - petrol - rear induction
DISPLACEMENT                 50.8cc
BORE                                43mm        
STROKE                        35mm        
WEIGHT                          1740g        
STATED POWER                5.3HP at 7,500RPM
R.P.M. RANGE                 1,300 - 8,000
PROP' RANGE                22 x 8 - 24 x 6
FUEL                                25 - 40:1                
SHAFT THREAD                Common 4 bolt pattern
SUPPLIED WITH                CDI - iridium plug - muffler - standoffs - tube spanner -
                                manual - bolt drilling pattern.

AVAILABLE FROM: Direct : -                

They just keep getting better! Readers who have been with me for a few years might have heard (whispers in the pits) that I didn't like petrol engines. I don't know how somebody can make a decision for you (whilst you are still sound of mind) but I can tell you this - it never was true. I certainly do like petrol engines, so much so, I have been writing a series on converting glow engines to spark ignition to run on petrol (now the stories will spread that I don't like glow engines). Fact was and is, I am not really keen on many of the convert engines - engines developed for (example) hand tool use such as chainsaws, leaf blowers and the like. I like any engine designed for model aircraft (boat and car) use be it diesel, glow or petrol. I know I am not alone here as we (modellers) are being offered some excellent purpose designed engines suitable for swinging propellers. The fact that some parts of the engine might be sourced from a mass supplier or manufacturer of petrol engines (any purpose) is no concern provided the crankshaft is suitable for our purposes and the engine is balanced to suit the RPM at which we will operate them. Actually, sourcing of parts is a good thing as it helps in keeping costs way down and…no problems with replacement parts.
As I said at first, they keep getting better and this engine on test is going to rank with the better engines I have tested in recent times. It comes ready to use and even has around 30 minutes on the clock to prove it is a good runner. All you do is fit it to your model using the supplied standoffs - fit a prop and give it some fuel. A couple of flicks and you are in business with a very impressive performer and very low vibration. I took particular note of the vibration as I noticed how smooth the engine was when it first started. Really impressive - so much so I had a real problem detecting any harmonic period. It was so subdued that it hardly affected the engine at all. Right throughout the testing I had no problems hand starting the engine hot or cold and it was really cold at the time (see below). I had waited for a while for better weather but magazine deadlines don't wait so I had to jump into the job even though the prop blast was turning my hands and face blue as I stood behind to take tacho readings. I must say, after a while I was so absorbed running it  - especially on the larger props - I was enjoying the moment watching the prop circle for quite some time that, when I reached forward to cut the ignition, my fingers would not work until I held them behind the exhaust system (my test equipment for re-directing the exhaust) and warmed them up. If you are in the market for an engine of this size you are in for two pleasant surprises being the use and performance of the engine and the very low price. Not only that - the guarantee is a definite winner.
Okay slipping back to the test bench, I will consult my notes (now with warmer fingers) and report my findings.
The testing was carried out on the 29.6.10 with the temperature ranging 9 to 12 degrees (over the test period) and 73% humidity - cold and moist, not the best conditions for running engines. Right from the beginning the engine was very easy to start by hand (no bites or frights), the transition was very fast and smooth, at any RPM reading the engine remained very steady, vibration was noticeably low with an almost undetectable harmonic period around 3,500 RPM. During the running the crankcase remained quite cold and only developed some warmth after the engine had been stopped for a while (transference of heat). This indicates a very smooth lower section with no binding or misalignment. At the completion of the testing - several hours  - the engine was absolutely clean - not even a seep around the joints. The iridium spark gave a good fat spark, Japanese Walbro performed flawlessly and the supplied muffler was no better or worse than this reasonably common style but - it did hold together well and did not leak at the manifold due to the steel/fabric gasket. I found the engine to run even better with a reasonable load - flywheel effect and I consider quite large propellers could be used if you have the need. Finally, no vices, a pleasure to run - an enjoyable engine.
Let us now examine the parts of it.

Cast aluminium alloy, very well finned, deep threads for exhaust manifold, well formed and generous internal fuel passages, squish band and hemispherical combustion chamber. Nice to see the plug at an angle to reduce overall height and vulnerability with inverted engines. Good job.
A note here on the surface finish of the cylinder which is course cast finish - roughish surface. Again the debate on surface finish is alive and well. Slick, shine, flat black or rough cast surface are the contenders and, currently, the rough cast surface is the top choice to win the debate. Apparently, tests carried out indicated that the greater surface area (of the rough surface) provided a better heat dissipation (cooling) so…that is the better way to go. Really, I do suppose there is merit in this as it has a certain amount of logic when you consider that long tapered fins have been proven over many years so thousands of tapered (mini) mountains would, apparently, have a similar effect. Well, heat is not a problem with this engine as it stayed well within the lower heat range - actually a little on the low side but, again, look at the temperature at time of testing.

Two parts CNC machined and highly polished. The front housing has two NSK (high grade) shielded bearings with an oil seal just ahead of the rear bearing. This seal is of the heavy duty design capable of withstanding considerable pressure. Being a two stroke engine, the crankcase design and sealing all add up to the very necessary 'Volumetric Efficiency' so necessary for good engine performance. Briefly, as the piston travels down, it 'pumps' the crankcase (positive pressure) to force the fuel gas in the crankcase up the fuel passages of the cylinder to the combustion area. The more efficient the pumping and crankcase design, the better the performance due to the increased efficiency. The seal on the shaft provides the - obviously - seal to prevent a pressure leak out the front housing through the large bearings. Similarly, in our common style glow engines there is a seal by the close fit of the crankshaft in the port area.
Continuing with the crankcases, the finish is very fine, fits are excellent and the rear case fits into the front with a machined in recess seal assisted by a soft rubber gasket compound. Excellent alignment, no movement possible and no gap leaks. The rear case has integral brackets for the standoff mounts and these are quite substantial at 8mm thick. The reed block/carburettor manifold is part of the case and it appeals to me that the entire carby, reed/assembly is retained by 54mm long 5mm caphead bolts that thread directly into the rear case rather than into the reed block as is often seen. The lot holds together well and the threads are well up to the job with little chance of stripping out. Below the manifold is a brass nipple for a plastic tube that connects the crankcase to the diaphragm of the carby for pulse pumping purposes.
All nicely done, neat and sturdy.

The crankshaft is forged steel (very tough) with a parallel front section 15mm diameter dropping down to 14mm where the propeller drive hub fits and is located by a large Woodruff key (half circle shape) Fortunately the drive hub is a neat slide on fit so it is not a great fight - as it is with many engines - to remove it should you want to replace the bearings, for instance. At the end of the shaft it drops down to an 8mm threaded section onto which the retaining collar/nut/prop support shaft is fitted to hold the lot together. Again a bit of good design as a standard long series socket does the job rather than having to make/modify a socket for the job. The 27mm long by 41.3mm diameter hub is tapped for 4 by 5mm bolts in the common four bolt pattern and a 5mm thick front washer is used.
On the rear of the shaft, in the counterweight, is the pressed in drawing pin shape crankpin for the roller bearing big end of the forged steel connecting rod. In the little end of the rod is a replaceable roller bearing for the gudgeon pin that is retained in the piston by wire circlips both sides.
The piston is one of those really tough numbers in a high silicone aluminium alloy - tough as a railway line - that is reduced in weight by having flat sides each end of the gudgeon  - no piston rock this direction - the narrow skirt sections have large apertures for porting and weight reduction and one cast iron ring is fitted. The piston is everything it needs to be including tough and very light in weight which would be a major factor in the smooth running of the engine - less reciprocating weight.

The carburettor is a Japanese made Walbro - WT 937 series - well matched and very reliable but here I see just one little shortcoming - the standard arm fitted to the throttle butterfly. Too short, hole to big for servo connection. You will need to solder a bit on to the arm or make up another fitting for ease of servo operation. When carrying out any modification in this area - be careful you don't lose the retaining screw in the throttle shaft. The thread on it is 4-40 UNF (generally) and this is a commonly available screw thread.
After the carburettor (in the assembly) is the manifold block - composite material - that insulates the carby from engine heat to prevent vapour locks - fuel heated up in the carburettor that stops the engine from running - and it forms the cavity for the reed assembly. Here we have the 'reed frame' to which the reeds are attached and from where they flex and seal for fuel induction. Sometimes these frames can be a bit flimsy and fragile - very easily damaged - and the screws holding the reeds and restrictor  plate, if not carefully installed during assembly, will cause small cracks in the plastic frame - a recipe for later problems. Not so with this frame as it is a very sturdy - extremely sturdy in fact - cast aluminium alloy job. No restrictor is incorporated (to prevent over-flexing of the reads) as the reeds, being made from Kevlar - carbon fibre - provide their own restriction due to their high strength and their fit in the manifold block. Nice work here.
The muffler is of the common style - maybe even a generic muffler as I have seen the same on other engines. Very nicely made, high shine finish, good thick manifold and bolts that bear only on the inside face of the manifold rather than squeezing the tubular body. The outlet is 22.5mm inner diameter and 93mm long so it will hang out most cowls but…it is not what you would call a quiet muffler. On the test bench I have a long muffler that I connect with flexible tubing to the standard muffler and this subdues the sound very nicely without choking the engine. You might consider similar if you fly at a noise sensitive field.

The standoffs are very well made, 68mm long and anodised blue which gives a tough outer surface. Bolts are supplied for both ends of the standoffs. At 24mm diameter they give very good support with no flexing.
Ignition is by the ever reliable and popular Rcexl CDI that has an extra lead for an onboard tachometer - they work very well - and you can expect long a good service from this unit provided you connect all cables correctly and keep the battery voltage no higher than 6Volts - NOT a 5 cell pack unless you use a regulator. For the entire test period I used a 4.8V 500mAh pack and it still had plenty of life when I finished the job.
Summing up, a well made engine, very good performance, good value for money and enjoyable to use.

(All wooden propellers used)
22 x 8                        7,100                1,550 IDLE
22 x 10                6,453
23 x 8                        6,763                1,200 IDLE
23 x 10                6,087
24 x 8                        6,265****
Considering the very cold conditions, these figures would improve slightly in better weather.

1        Well designed standoffs give good support without flexing.
2        All aluminium muffler with a super fine finish.
3        Iridium spark plug - very high quality. Note the small centre electrode.
4        Four reeds on the reed block and all are made of carbon fibre.
5        Solid prop drive hub with the ignition magnet. The threaded holes for the prop
        bolts are deep and of a good quality thread.
6        In front of the rear main bearing is this very substantial oil seal to maintain the
        crankcase seal for volumetric efficiency.
7        Manifold aperture in the rear case with the 'through all' bolts. The blue tube is
        for the pulse pressure to the carburettor.
8        Note the imprint 'JAPAN' in the top right corner of the Walbro carby.
9        Very low profile with the plug set at an angle in the head.
10        Super lightweight piston made of super tough alloy.
11        Rcexl CDI for ignition. Reliable, popular. Maximum power requirement is 6V.
12        Low tip noise and very effective Hawk propeller supplied for testing.
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