got a few questions to ask. 1. Whats special about the shape of 2 stroke exhausts? theres nothing inside them? 2. If all 2stroke exhausts are hollow, how do they differ in performance? 3. How do the crank bearings get lubed if you run premix? i thought nothing can get past the piston rings? 4. How is porting and flowing measured? If anyone can answer these questions id be most greatful as the curiosity is doing my head in haha
1 & 2, the expansion chamber of a 2 stroke exhaust and its shape determines the nature of the powerband, with the powerband itself coming into play at certain RPM and supercharging the engine with a sonic pulse pushing mixture into the engine through the header pipe, as this gif shows http://southernskies.net/page_pics/miss/two-stroke_c.gif Because powerbands only come in at a certain RPM and for a short amount of time, to make it longer and more powerful, the pipe needs many coned sections, all with different angles. It's pretty damn hard to make an expansion chamber the best it can be because of how difficult the physics are of making the pipe itself. I have a German 3 piece expansion pipe on my MZ and the powerband only lasts a couple of seconds through 2nd and 3rd. Although the pipe was only 30 quid new 3: Premix or not premix, the same mixture still gets into the engine, as you can see in the gif, the mixture gets sucked down into the crankcase then pushed through the transfer ports as the piston comes down, compressing it out of the crankcase and into the combustion chamber, while the mixture is in the crankcase, it's lubricating the bearings, hence why oil is added to the petrol in the first place, along with lubricating other parts. Wow I feel smart, why am I even doing Health and Social Care at college...
Exactly what I was going to say but couldn't be arsed to type that much, you need to get a book on 2t tuning and read up or look on the WWW.
Thanks for the info mate i had a general idea and my ped runs premix so i know it works haha just wanted to find out why exactly it works, iand just didnt understand how the amount of cones in an exhaust pipe mattered. Do gases like swirl around inside the expansion chamber?
ahh ahh right, also got another question. I know it sounds silly, but ive got a 70cc runner and my exhaust snapped other day, ive got a 125cc runner exhaust lying around, will this work on my 70cc? im guessing any exhaust is better than no exhaust
It can't run without an exhaust, however a 125 exhaust will NOT work. The shape is all wrong and I don't even know if it fits Sent from my Nexus 4 using Tapatalk 4 Beta
I said it can't as in it won't last very long, surprised it hasn't seized already Sent from my Nexus 4 using Tapatalk 4 Beta
