Mastermind Revisits the MS661

[Mastermind]

Smaller saws like a bunch of compression, the bigger ones don't seem to need as much.

 

[sawmikaze]

Smaller saws like a bunch of compression, the bigger ones don't seem to need as much.

How small kemosabe ?

 

[Deets066]

How small kemosabe ?

Pole saws, they like about 275 psi

 

[Mastermind]

How small kemosabe ?

From what I've seen.....which is always under review my me....60cc saws and smaller need more grunt. Compression makes grunt. Now, like any good thing, us saw junkies can overdo it. I'm not saying that they need 300psi to run.

 

[sawmikaze]

From what I've seen.....which is always under review my me....60cc saws and smaller need more grunt. Compression makes grunt. Now, like any good thing, us saw junkies can overdo it. I'm not saying that they need 300psi to run.

Ive gots me a 60cc saw that blows 177..its pretty sporty with a 20" bar but ive never tried it with anything bigger to see how strong it really is.

Ive got a 40cc saw that goes pretty hard too...

 

[junkman]

Ive gots me a 60cc saw that blows 177..its pretty sporty with a 20" bar but ive never tried it with anything bigger to see how strong it really is.

Ive got a 40cc saw that goes pretty hard too...

What are small saws like that for ? climbing ?

 

[Stihl working Hard]

Seriously good information coming in guys I love it keep it coming riveting thread

 

[CR888]

The Solo 681 in stock form has THE highest BMEP of ANY modern saw. It also has an unrivalled power to weight ratio. Many builders would loose performance porting them using traditional methods that had worked on other saws. The 681 should provide good study for the keen builder and I am so glad Randy is starting to unravell the concept behind the engineers design. We need to stop and take a good look when a 81cc stock case/p&c will knock off a ported 90cc pro saw from the major two. I am so pleased Randy is looking at this from every direction and is happy to discuss his findings. The engineers were not following the pack when they designed this saw. It also met the US strict emission rules too without compromise. I bet the strong running 661 has some design similarities! Monkey smart!

 

[Moparmyway]

We need to stop and take a good look when a 81cc stock case/p&c will knock off a ported 90cc pro saw from the major two.

You're getting a little carried away here

 

[mdavlee]

You're getting a little carried away here

Not really. Watch the 681 and 661 videos. Pretty well same cut time at 20-21 seconds each cut in that log. He may have been around back when the 681 build happened on race saws as well. Everyone over ported and most were slower than stock.

 

[CR500]

Last one I did is 98 120 83 180lbs
Very little grinding and it's a great runner. I like the higher exhaust

Was that with the 1st or second cylinder?

Found some bigger wood to try her out on. Dolmar is patiently waiting to get a workout lol

Sent from my non internal combustion device.

 

[jmssaws]

Was that with the 1st or second cylinder?

Found some bigger wood to try her out on. Dolmar is patiently waiting to get a workout lol

Sent from my non internal combustion device.

First one. Gonna try a high exhaust on the second. I'm impressed with how the first one runs.

 

[CR500]

First one. Gonna try a high exhaust on the second. I'm impressed with how the first one runs.

Alright keep testing!!!

Sent from my non internal combustion device.

 

[hseII]

What are small saws like that for ? climbing ?

Yes,
And Palm Tree Felling.

 

[Moparmyway]

Not really. Watch the 681 and 661 videos. Pretty well same cut time at 20-21 seconds each cut in that log. He may have been around back when the 681 build happened on race saws as well. Everyone over ported and most were slower than stock.

While that may have been true back when, it certainly doesn't ring true with the latest 90cc saws, especially the ones coming from Missouri.

No disrespect to the stock 681, but put a 36" on it and it doesn't keep with any ported 90cc that I have.

If he would have compared stock to stock, I wouldn't have posted anything, but comparing a stock 681 to the latest ported 90cc Stihls ??????

 

[mdavlee]

While that may have been true back when, it certainly doesn't ring true with the latest 90cc saws, especially the ones coming from Missouri.

No disrespect to the stock 681, but put a 36" on it and it doesn't keep with any ported 90cc that I have.

If he would have compared stock to stock, I wouldn't have posted anything, but comparing a stock 681 to the latest ported 90cc Stihls ??????

Oops. Missed the stock part.

 

[bryanr2]

stock for stock 681 wins. saws about as close to a factory hot rod as they come.

 

[jacob j.]

Like on the Solo 681, rather than worry that I had far too much intake, I thought that if I have that much intake timing, maybe I need to take all the other numbers higher.

Well......I did that a few years ago, but I made a turd. This time I decided to increase all the durations......except the transfer duration. Instead of increasing transfer duration, I increased blowdown.

That's what they make Devcon for...

 

[jacob j.]

One of the strongest 7900/681'ive run has a high exhaust and low compression. Runs a 9 pin and 28" pretty easily.

I like higher exhaust. Most of my stuff was 2-8 degrees higher than what Randy has been doing.

Case capacity is easy to test with some fluids. Just have to level the case off. Put the crank at bdc. The other thing is the stuffer doohickey.

Keeping transfers smaller by whatever means will help velocity. Might be a pop up or even trimming the piston there. You just have to play with this stuff. Madsens gets 12-15% on a dyno over a stock 661. They cut the piston for their changes.

Most of Madsen's work involes modifying the piston, and they turn out of a lot turds...

Once in a great while it works out but I'm not a fan of their worksaws having bought several brand new.

 

[jake wells]

Most of Madsen's work involes modifying the piston, and they turn out of a lot turds...

Once in a great while it works out but I'm not a fan of their worksaws having bought several brand new.

madsen does better work than mr blue goo.