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Thanks 👍

Thanks Doc!

Real tough to compare what is in a video to what is in your hands but with all the mods you can get a pretty good gain out of the stockers

Thanks! Hope it helps clarify things a little!

👍🆙AP

Exactly! Calculating speed of a pressure drop is way more complex than the degrees between exhaust and transfers!

Thanks Jon Bob!

👊

Thanks!!

Thanks! I stumbled through it but i think it should help some people!

@Super-Dave-Outdoors Nah. Those who don't know won't watch and those who already know...well they already know. It's pointless. Just have fun and enjoy making videos. No one seems to listen to anything of substance. Seems like everyone must learn in their own way. And blowdown is a very simple concept that rolls off the tongue and is absolutely nice and easy... so it works for a lot of people to focus on. The idea of a pressure differential is a bit more complex, folks don't seem to get it. So they go right back to talking about blowdown. I've built saws that ran great, but then went back in and just widened the exhaust... boom! It went from great to exceptional. Why? The exhaust pressure dropped faster and allowed the transfers more time to flow the fresh mix. But blowdown wasn't changed in the slightest.

It is a legitimate concept but it has been perpetuated incorrectly by so many that any beginner gets sucked into the myth. I'd rather help direct a fresh mind than attempt to change a rotten one.

​@@Super-Dave-Outdoorssomewhat of a fresh mind being directed here 👍🆙SD👊

Eagerness and logical thinking go a long way!

Yup! Anything that bottlenecks before or after the port can affect it. I think 99% of us are picking numbers arbitrarily and fine tuning with trial and error. Effective, not efficient! If you think about it in reverse blowdown pressure also affects the intake with the standard atmosphere and changing pressures in the crankcase.

Morning😊

Got a long way to go before we get there. But the basic answer is with bore gain you gain possible port width and with stroke you gain mechanical advantage via leverage from stroke. Far more variables involved to say which will make most power but short answer is whichever exerts the most pressure per stroke at a given rpm is going to make more power.

Thanks!

💯% helping me!

@@Doc-Cole_Trickle-of-Chainsaws yessir👍🏻

No problem, don't make mower belts harder than they need to be!

Sled racers, Moto GP, 2 stroke drag bikes/quads, jet skis/PWC/outboard boats all know what is going on. 99.9% of the chainsaw guys are only scratching the surface, myself included.

@@Super-Dave-Outdoorsis probably the only chainsaw guy to have even read an overmars book.

Only book i have is the graham bell one but i am going to look for the overmars book now. Soon as i have the extra money i am purchasing the mota 2 stroke simulation software Edit: Oh frits overmars!, i have been trying to find a book by him or Jan Thiel, any recommendations?

Yup, not trying to create problems but if any arise i aint afraid of solving them lol

Regular Vanilla Ice

@@crazyfeller5704 😁

Trying to! More complex stuff to come later on hopefully!

😁 Proudly consider myself part of the SawDorkian tribe!

I'm honestly trying to help with this one. No shade thrown at anyone but with the mass amounts of uninformed, misinformed, illogical videos out there on the subject i was doing my best to clarify what i could.

@@Super-Dave-Outdoors well put IMO, if I understood... then I think whoever is going 2 start traveling down this road will 2 or someone who's already on this road will come away w/ a better understanding of the whole picture. When's Pt2? Teach on!!

Dont know about pt 2 yet but I may break down a few things to increase my understanding too.

@@Super-Dave-Outdoors 👊

yup. 4910 had a semi chisel RM and 620 was running full chisel EXL. I bet Brisco's hot 4910s are faster than his 620s now. Just cant build enough compression on a 620 to push the durations like a 4910.