Bob27

I have done a lot of that type of research in the past. This isn't the first 2 stroke I have ported, I think it is my 4th or 5th and so far I have had nothing but good results. So I am no beginner, but I do have a lot to learn. I actually just barely got the engine back together and I have been running it without the prop. It is interesting the results I am seeing already. It sounds different which is typically when you open up the exhaust port. It is also way more responsive to throttle input and I think it would rev to the moon if I didn't stop it. I do have a buddy that can thrust test the engine so it will be interesting to see how much it changes.

So, I am currently in the process of modifying a paramotor engine(radne racket 120). I'm trying all the fancy stuff like ceramic coatings, porting and polishing, shaving all the unnecessary weight, and more. Has anyone had any experience with this? I probably should have started this thread before I started modifying my engine...

From what you are saying, the low jet still sounds way too lean. You will likely need a lot more than 1/16 of a turn. Anyway, if I were you. I would check engine temperatures. If the engine is still running in a reasonable range, I would figure out what you did and patent it. Lol

I wonder. My only thought is that of it is not made of the proper metal it could crack after a while or on a 2 stroke, the shockwave could baffled going through there like on a suppressor.

I ran across a potential paramotor new exhaust joint design(see the linked image). It is capable of bending in any direction, it can be slightly compressed and stretched, it eliminates the need for any springs or bushings that can go bad and overall it could simplify the exhaust design. My only concern is that this design may weaken the shockwave from the engine even more than our current design, but I lack a degree in aerodynamics to fully assess it. Believe that the primary goal would be to get rid of the bushings that many exhausts need replaced 100 or so hours along with the springs which can break or be lost. Also the ability for the joint to compress and stretch could help protect the tuned pipe even better from vibration and allow for a lighter exhaust.

Radne Racket racket 120 engine for sale. The engine itself has great compression and appears to have fairly low hours. Asking only $1500 OBO Also comes with motor mounts, aero tuned pipe and muffler, throttle, fuel line w/ filter and hand pump, 51" genuine helix prop w/ hardware, and a professionally machined prop spacer. In total the extras are worth over $1k Here are some specs: Horsepower- 15 (~10kw) Thrust- 130lbs Weight (engine only)- 15lbs (6.8kg) Weight (w/ mounts, exhaust, fuel filter, fuel pump & throttle)- 21lb Displacement- 118.8cc Reduction drive ratio- 3.3:1 Other cool features about this engine: The low power to displacement ratio makes it one of the most dead reliable and bullet proof paramotor engines all while being one of the most efficient. This engine weighs less than the atom 80, produces more thrust, and needs WAY less maintenance. All while maintaining the same low noise and fuel consumption. This is the manufactures website: https://www.radne.com/product/raket-120-aero-es-rd-ratio-13-6 If you want to know more about the engine I am selling, or their 46 year history of them making engines you can find out more on their website.

Exhausts can create massive differences in your power output. Heck, I could build an exhaust for your vittorazi that could give the engine 45hp. The difference is that my exhaust would give you 45hp only within about 5 rpm of what I set it to. Even 15 rpm off from the tune length and you would be lucky to get 15hp. Anyway. Exhausts are built around a compromise between peak power and the power band.(Wider power band= less peak power) They can also be built to deliver peak power almost anywhere in the power band based on the length from the engine to the back of the expansion chamber.(longer=lower rpm power). Anyway my point is that the expansion chamber that you choose can and will make a massive difference in how your engine performs and many of the engines characteristics.

But does your atom 80 have 27hp? Lol One big problem is that at lower loads the engines loose more efficiency(2 strokes are way worse in this aspect then 4 strokes). So a vittorazi engine while cruising is running at about 1/5 power and gets a calculated ~6% thermal efficiency. On the other hand your atom 80 is running at closer to 1/3 power cruising and thanks to this extra load gets roughly 8-9% thermal efficiency at said power. But at 90% throttle both engines are close to 10% efficient. The big idea is that 4 strokes don't loose efficiency at low loads as bad as 2 strokes so that you can have the power of a big engine with the cruising efficiency of a small engine.

I tune my 2 stroke engines almost entirely off of sound so it's sort of hard to explain. Basically if your engine sounds smooth without very many exhaust poping sounds, then you are lean and the needle needs to turn counter clockwise. If there is a ton of poping sounds, then you are likely rich and you need to turn the needle clockwise. This way can be difficult for people learning to tune. For your specific engine it sounds like the idle is slightly lean so I would try going like 1/8 turn CCW at a time until you get the best throttle response. If it gets worse reset the needle to where it was and try going the other way

From my experience with 2 and 4 stroke motorcycles and other engines these are the rough and speculative advantages and disadvantages of the eos 4 stroke. Advantages: Quieter, more more fuel efficient, less vibration, no spark plug fouling, no oil mixing, wide power band, no explanation chamber. Disadvantages: Complex valve train that is maintenance intensive, very frequent oil and oil filter changes, top end rebuild intervals likely every 75 to 125 hours, lots more parts that can fail, will likely cost a lot more than a 2 stroke.