Sworks322 Posted July 29, 2022 Report Share Posted July 29, 2022 Provocative title right?! You're probably thinking the same thing I was when the idea was first presented to me... 'That's just stupid! That's not how reed valves work! You can't have multiple cylinders without multiple reed valves!' etc... etc... So before you start explaining all the physics, in technical or even laymen's terms... I know... and believe me I feel just as silly asking the question as you probably do wasting brain power to entertain the idea. However... I promise this isn't an April Fools joke. I'm currently working on a project with a fuel injected twin cylinder two stroke that uses a single VForce4 reed valve for both cylinders, with a combined displacement of almost 300cc. And here's the best part... the crankcase is a single chamber. When you remove the reed valve assembly and look into the intake, you can see all the internals, including both connecting rods and pistons, sharing a single crankcase chamber. This didn't compute at first, for a guy who "grew up" (questionable) working on Banshees and two stroke outboards. Some of you may have deduced by now that I'm talking about an opposing cylinder engine with both pistons firing simultaneously, which addresses balance issues as well as supplying fuel/air mixture to both cylinders from a single crankcase. Unfortunately, I don't have complete confidence that our engineers did all their homework when designing and/or selecting certain components of the system. Engineers tend to get into the mindset that they're the first person to try to solve a particular issue and think they have to make it up from scratch instead of comparing notes with the guys who've been tweaking and improving some previous engineer's half-baked design for the last 40+ years. Anyway, I digress... I know I've learned a heck of a lot from this forum over the years so I figured what the heck, maybe some of you tuning gurus would be able to educate me! So here's some of my questions... - What, if any performance impacts would you expect to see using a single V4 144 reed valve to supply nearly 300cc combined displacement? This seems undersized to me. - What impact would drilling a small hole (1/8") through the reed block have? (Their goal was to allow excess oil to seep out at a specific location, rather than pooling "downstream" of the reed valve. My concern is that I know firsthand how much of a performance impact reeds that aren't seating properly can cause just due to the small gap that opens at the tips of worn reeds. So wouldn't it stand to reason that drilling what is essentially a bypass hole around the reeds would have a similar effect? - How long do VForce carbon reeds usually last? Most of this engine's hours will be between 5000-7000 rpm for several hours at a time... any speculation if this will increase or decrease the reeds' life span? If anyone is familiar with something like I'm describing, I'd love to hear some real world experience and insight, but I'm open to just about any discussion or questions that may open my eyes to something I hadn't considered yet. I'll even entertain some joking, ribbing, or just plain brow-beating if that's the price I have to pay for wisdom, haha!😜 Thanks in advance! RoHo Quote Link to comment Share on other sites More sharing options...
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