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DIY engine from scratch, billet cases


arthurmoto1
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Hi all! I'm from Ukraine the  land of Klichko brothers. So sorry for my English. My buddy is fond of paragliding and I'm a mechanic of local MX team. So you guess the only way we have is to build the engine from scratch ourselves. Actually he is experienced paraglider and his first engine was bought from the factory but this was the only one he bought. All others were built. The next one is in process and I'm here with intention to show you this building step-by-step. 

 

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Actually I was not impressed by the quality of common in paramotorgliding engines such as Moster, Polini and so on. I personally have a huge experience in engine rebuilding and I think many engine parts or the way they are manufactured are under the level used in MX engines building. Don't get me wrong some parts are reliable for example Vertex pistons. But in most cases the problems are connected with the wish to make engine as light as possible. So you can see chinese crap quality very small electric starters, cracks in the halfs, broken bolts because of small size, etc. Another problem that OEM paramotors parts are very expensive despite of sometimes poor quality. So according to this the first time we started the building of DIY engine we had the aim to achieve high reliability of the engine especially under full load and to use  common and nonexpensive parts with shortterm availability. According to this the corner stone of the engine was cylinder selection. We were in need of 150-200 ccm small size nicasil plated cylinder without powervalve and the only option was the part from italian Piaggio scooter bigbock  180 ccm engine. The original parts quality  of nicasil is top notch, pistons and rings are highly available. And after all this choice proved itself as very reliable. There are many aftermarket bigblock cylinders but the most powerfull is Parmakit you can see on photo. Sorry time to go. Next time I'll tell more. 

Cheers!

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But this is not the only engine we are working on. We need really powerfull engine with high torque. We are looking to have at least 50 Hp at full gas. Application will depend on the weight that is unknown for now maybe paratrike. But I hope it will be able to fly without wheels. Look at photo this is the cylinder with reed valve, power valve and two Walbro carburetors. 

Cheers!

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Whatis about #1 billet cases. Just imagine that the largest in the world airplane AN-225 factory is only 120 km far from us. And it was time when this enormous size factory has its own MX team. And my buddy was a member of this team so from the very beginning many years ago it was possible to see a lot of amazing things. Now this time is gone but not completely. There is another small factory much closer to us that makes jet engines rebuilds. And these crankcases are made from the solid  aircraft grade aluminium alloy at this plant. The thickness of the walls is 5 mm that is needless in many areas and after test period it will be decreased a lot to save weight but not to weaken the construction. Despite of shaving off the material to compete with the weight of common engines our goal is to make the strongest ever and most beautiful crankcases.

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Honda CR250R. This will be a pilot project to see what kind of power is possible to have from MX engine. So we used just old broken parts like this jug, crankshaft and cases from old MXer. I suppose the use of KTM 360 ccm engine parts could be more suitable or even CR500R or Kawasaki KX500 to have more power. The conclusion will be done after testing. Now I can show you crankcases with waterpump, mainplate, starter, belt pulleys. Enjoy! 

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#1 something like Moster 185 has but with more HP and 200 ccm. But look we can produce cast crankcases the same weight as any other engine on the market has. But with billet cases it is possible to have the same weight with more strenghth because of stronger material. Or to make them lighter but the same reliability. But I don't like the idea of manual starter at all, only electric starter. And I don't like the power and build quality of those tiny chinese starters used in other engines. We use Piaggio OEM starters (actually japanese Mitsuba) with great success. But it has more weight and starter clutch has more weight too. However they provide such power that you can eliminate decompression chanel by exhaust port to have more HP or to enlarge displacement of the engine. What's about displacement a bunch of 180 ccm engines has 66 bore*54 stroke. This is possibly the only way to have light and really powerful engine. But such the short stroke makes these engines pipey and their HPs are in narrow range of revolutions. To widen this range and to have more torque these engines need more stroke and I hope I can make crankshaft with 59mm stroke to exceed 200 ccm. And with the intention for this we have made thick walls of crankcases to have possibility of enlarged crankshaft installation. In conclusion I consider the weight of engine #1 may be like 500 grams more then competitors have but  with more reliability and power.

 #2 no idea for now.

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Hi all! So what? I can manufacture any part your engine has or replicate it the whole but I don't think the weight itself is the most important feature.   The aim is to make more reliable engine with the same weight  other common engines on the market have but with the use of highly available parts you can buy on Ebay. For example connecting rod is from 125 MXer that can easily handle 40 HP and the price on Ebay is $60. What's about  weight everybody talks how much the engine weights (+/- 2 kg) but nobody wants to talk how much the pilot weights itself (+/- 20kg). So sorry weight is not our priority.

Cheers!

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There is not way to make really powerfull engine with paper-thin parts. Look any MX 280 ccm 2T engine makes 60+ peak HP. This must be much more than 100 kg thrust. For instance Moster 185 has 25 HP and 75 kg thrust. What max thrust does your engine have in kg?

Just let's compare KTM SX250 and Honda CR250R. KTM is lighter but it has broken parts all the way, crankcases, mounts, swingarm, rimlocks, spokes and so on. Then you have to change as much as possible parts just to have possibility to finish the race. 

What's about reliability for example such motorcycle manufacturer as Triumph from UK tests their engines during development cycle at full gas 300 hours without problems.

I just can look at your engine inside at transfer ports, conrod, bearings, cases and say approximately the level of HP it has. And what carb does it have? Walbro? I think your engine has under 100 kg of thrust.That is the only way for thin and small unreliable parts to work without problems - just to weaken the power. It's definitely not for us - about #2 engine we need 250ccm 50+ HP 130+kg engine. 

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Thing is, for most paramotoring here in the UK we don’t need really powerful engines but we do need reliability, and low fuel consumption is a given. Trikes aren’t big here, though there are a few, and there’s no way I’d want to foot launch a big lump like that. Reliability however; always welcome. 

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We are not manufacturers of engines and are not going to sell them. I'm MX wrench and my friend is car painter. Moreover I'm afraid of flying and did not fly at all. I have motocross+ countrycross+ enduro+ rally racing I participate to have no time for something else. So the only reason I'm here is just to share our experience. We have such competition here that you have 3 hours to fly from the point as much distance as you can with the landing the same point. So 2020 we took the second place. You see the wing has to be under 20 sq. m to fly fast and ours is 17 sq.m. And the engine must be powerfull and reliable to work under full load so long time. 

When you talk about reliability it's worthless to say your engine is reliable. The load on the engine will vary much with usage of different size wings. Our old 180 ccm engine that has 80 kg thrust works almost on idle when using 23 sq.m. wing but has much more to work with 17 sq.m wing. So the difference in reliability and fuel consumption will be huge, agree?

And what is your wing in sq. m. and how many hours of flying you have per year?

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On 25/12/2020 at 10:40, arthurmoto1 said:

but nobody wants to talk how much the pilot weights itself (+/- 20kg)

I does tickle me watching someone talking about the (part x) which is 3g lighter than the next lightest part and so on (all while munching on a pasty and chips (or similar) lol

Welcome to the Paramotor Club and thanks for sharing your projects here :-)

SW :D

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4 hours ago, admin (Simon W) said:

I does tickle me watching someone talking about the (part x) which is 3g lighter than the next lightest part and so on (all while munching on a pasty and chips (or similar) lol

Welcome to the Paramotor Club and thanks for sharing your projects here :-)

SW :D

Ah but 1kg around the middle is much easier to carry than 1kg on the back 😉😁

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I'm quite interested with this build and I can't wait for more updates. 

 

I have been thinking of doing something like this except building the engine nearly completely from scratch. What I want to build is an opposed piston ~150cc paramotor engine with comparable power to a vittorazi moster. The hard parts would be making the dry sump oil system, super charger, and gearbox to connect the two crank shafts together. Theoretically it would have the advantages of a 4 stroke such as no fuel mixing, quieter(no expansion chamber), cooler operating temperature, broader power band, longer lasting spark plugs, and high fuel efficiency. It would also have many advantages of a 2 stroke such as being more simple without a complex valve train, comparable or better power to displacement ratio (more efficient scavenging, running a 2 stroke cycle, supercharged), and it should be cheaper to produce than a 4 stroke. 

Anyway, I have been researching into different ways I could make it and was curious if you would have any suggestions.

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I think that idea to divide 150 ccm in two cylinders is not suitable for paramotor application because of huge loss of torque. There was such italian scooter Italjet Dragster (if I'm correct) the only one on the planet with such engine but it was not successful. But the same scooter with Piaggio bigblock engine became a legend. The key is torque. If you need more power you have to use multicylinder engine, the more - the better. But you can receive peak power in small RPMs range somewhere very high. But in case of paramotor you need linear power and torque you can have it only using single cylinder with long stroke and preferably long connecting rod. And I don't believe in 4 stroke because it is weak, more complicated and weights more. Charging is a problem itself because it is not only makes the engine more complicated. It makes the problem of heat dissipation from the piston to sleeve. But you know the overheating of paramotors is a common problem itself. That is why there is no one supercharged motorcycle engine despite of many  attempts of manufacturers.

When you decide to build your own engine you have not to forget about balancing. You know that paramotor is not connected to the ground of has a 200 kg frame so it will vibe. It should be balanced but the balancing factor differs according to the position of cylinder, for instance on the same engine up-down position will need absolutely another balancing factor if compared to left-right position. 

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