The Chitty Avatar MS661 Donate To Win
- Thread starter Mastermind
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Adirondackstihl
Flyz, Fuel & Fotos
The PlumFund account has been set up.
Just waiting on bank account confirmation.
Should be 2-3 days
We will be running this until December 20th, 2014
Just waiting on bank account confirmation.
Should be 2-3 days
We will be running this until December 20th, 2014
LegDeLimber
Addicted to ArboristSite
perhaps a subtle, early warning of those $300 hand pieces getting closer to failure?
Tiny little vibs from bearings getting rough or teeth mesh getting looser
would add to how much the nerves light up from running them.
Any chance that you notice more fatigue, tingles, burning sensation
as they get closer to failure?
LegDeLimber
Addicted to ArboristSite
I'm having the same "strato charged my a.." thoughts.Like a oversized MS461.....
But did you guys ever decide what that lil athletic cup looking thing bolted onto the intake side of the cases actually does?
forgive me if i've missed a definitive thread about it, elsewhere.
Four Paws
Addicted to ArboristSite
So, Randy, for the sake of discussion... Based on your post above, I am inferring that you felt your desired blowdown was more important than achieving primary compression of 40 degrees? This is good at illustrating there are always trade-offs and compromises when building any engine, be it a single cylinder 2 stroke, or a big-block V8.
Mastermind
Work Saw Specialist
A certain blowdown number was not my primary goal. Precise exhaust, and transfer opening points are far more important in my opinion than blowdown.
This engine has a very small crankcase. Bore size has been increased to 56mm, so it has a shorter stroke than a 660. All that sort of stuff changes port timing considerations.
On a two port engine (like a MS660) we can get the transfers up as high as 114 degrees ATDC before the engine starts getting peaky. I think that is because the transfers are wide open and slow flowing.......sorta lazy if you can picture that. They need to open sooner so they have time to get the mixture moving.....
On the Dolmar 7900 the transfer opening point has to be much lower. That engine has a very tight crankcase, and very small, high velocity transfer tunnels. Port a 7900 like a MS660.......and you've built a turd.
Blowdown time isn't really something I think much about.
Here's another thing to ponder........
The 562XP has about 10 degrees of blowdown......
This engine has a very small crankcase. Bore size has been increased to 56mm, so it has a shorter stroke than a 660. All that sort of stuff changes port timing considerations.
On a two port engine (like a MS660) we can get the transfers up as high as 114 degrees ATDC before the engine starts getting peaky. I think that is because the transfers are wide open and slow flowing.......sorta lazy if you can picture that. They need to open sooner so they have time to get the mixture moving.....
On the Dolmar 7900 the transfer opening point has to be much lower. That engine has a very tight crankcase, and very small, high velocity transfer tunnels. Port a 7900 like a MS660.......and you've built a turd.
Blowdown time isn't really something I think much about.
Here's another thing to ponder........
The 562XP has about 10 degrees of blowdown......
William Balaska
Addicted to ArboristSite
Nice build for a good cause. Just one question about the 661 after its been built will it pull on a stock 395xp. Love my stihl but I learned a lesson when I bought a 395 it's just plain nastier than the 660. I like your lathe set up I have an atlas with a four jaw chuck seeing your mount gives me some motivation.
UnforsakenGhost
ArboristSite Operative
I have no idea what that means, I guess that's why people send their stuff to you lol
banana boat
ArboristSite Operative
I want to buy tickets...
andydodgegeek
The stool maker
Sweet, nice job Randy.
sarahdodgegeek
The shirt lady
Randy, you are one good dude.
Adirondackstihl
Flyz, Fuel & Fotos
Magnum783
ArboristSite Guru
I do too how do I buy some must have a shot at this
Work Saw Collector
GTG Coffee Maker
Guys we will post a link when we get the account all set up.
It is in the works. I'll update when I know more to tell.
Stephen
David (saltas)
Addicted to ArboristSite
bump
RiverRat2
Serio Tree Freak
Yeah I'm picking up what your laying down,,, Ala the MS461 the 661 has the crankcase stuffers to help with building/boosting more intake charge velocity that gives these new saws better performance right @ stock form,,, even with the shorter stroke and barely smaller displacement. unless I have it inverted???
and then you go creating more bannana stuffing places and flow angle enhancement... wowzer
Beer Gut
A Fine Pilsner
A little late but awesome thread. Cool pics
UnforsakenGhost
ArboristSite Operative
Yeah I'm picking up what your laying down,,, Ala the MS461 the 661 has the crankcase stuffers to help with building/boosting more intake charge velocity that gives these new saws better performance right @ stock form,,, even with the shorter stroke and barely smaller displacement. unless I have it inverted???
and then you go creating more bannana stuffing places and flow angle enhancement... wowzer
His nickname is monkey mind, so banana holder make sense
Work Saw Collector
GTG Coffee Maker
https://www.youcaring.com/help-a-ne...orial-"I have a potty mouth"/258288/donate#wp
Ok here it is, 10.00 donation, add username.
Ok here it is, 10.00 donation, add username.
