Mastermind Meets The MS660

[Mastermind]

I've heard that the MS660 just doesn't respond that well to mods, and until the last few weeks I would have agreed. I've built several, and noted that the exhaust timing was too high......at least for a worksaw.

The last two I've done I cut the squish band in order to lower the jug and change the exhaust timing to a more realistic number.

Here's a few pictures.

I'm of the opinion that the transfers are key to a strong running saw. They don't necessarily need to be wide.....just at the right height. These are at 120° ATDC. As you can see not much has been done to the lowers, just clipped the lip from the bottom.

The exhaust port hasn't been altered at all. No widening or raising.......totally stock. The timing on this port is at 100° ATDC

The exhaust flange was widened and the roof was raised. It was then tapered into the port at the cylinder wall.

The intake floor is at the stock height as well, though it is now at 85° ATDC. It was widened .050 or so on both sides and the roof of the port was raised about .050 The shape of the port has been squared up a bit as well to increase time/area. .050 was taken from the cylinder base.

The muffler was gutted and the flange was matched to the exhaust flange.

The trick on the 660 IMHO is in cutting the squish to both raise compression and alter the port timing numbers. This saw now has just over 200psi and is a beast.

[video=youtube;sBcB4wmzYMI]http://www.youtube.com/watch?v=sBcB4wmzYMI&list=UUg2yelCeKwB12xIohZfmf1g&feature=plcp[/video]

 

[young]

this mastermind is sure a chainsaw whore. just saying.



btw nothing wrong with whores in my book. just saying.

 

[Mastermind]

this mastermind is sure a chainsaw whore. just saying.



btw nothing wrong with whores in my book. just saying.

Nope................He's a chainsaw slut. :msp_rolleyes:

 

[young]

stihl jug? or mahle?

 

[o8f150]

Nope................He's a chainsaw slut. :msp_rolleyes:

chainsaw slut??? i heard just a slut:hmm3grin2orange::hmm3grin2orange::hmm3grin2orange:


oh yes,,nice work as usual

 

[Mastermind]

stihl jug? or mahle?

Stihl........

 

[young]

i think i need to buy another saw so this mastermind joker can.........do stuff to it.:msp_ohmy::msp_ohmy:

 

[Mastermind]

i think i need to buy another saw so this mastermind joker can.........do stuff to it.:msp_ohmy::msp_ohmy:

Yeah....like you need another saw.

 

[young]

Yeah....like you need another saw.

is this not arborist site chainsaw forum?!?!?!?!? cause i swear someone just asked me if another saw was needed. aaaaaaaaaaaaaaa YEA.:msp_razz:

 

[booger1286]

I really dont understand how anyone can gain anything by raising exhaust? Seems like that would just take away torque?I also dont understand how a long blowdown would ever be good unless you have very little crankcase pressure? Makes sense what you did with this saw i like it.

 

[HorseFaller]

Very good stuff.

 

[Mastermind]

I really dont understand how anyone can gain anything by raising exhaust? Seems like that would just take away torque?I also dont understand how a long blowdown would ever be good unless you have very little crankcase pressure? Makes sense what you did with this saw i like it.

Hold up there. Raising the exhaust is very necessary on MOST saws I build.

The new 660 just has too much exhaust timing from the factory to be able to raise it........it benefits from less exhaust.

 

[fastLeo151]

Randy your work sure is purdy!

Andrew

 

[mopar1rules]

Mastermind, I agree that the ms660 comes with too wild of an exhaust duration. I personally like 155* for exh durations and never over 160*, if the saw is to be used for work. Your saw appears to run like mine. We did things different, but in the end both made it better than stock. In stock form I HATED my 660. I would have rather cut with my 044. Tonight here, I just finished a 046 project....machined a old mahle 066 piston, to work in a big bore and to help lower durations on port timing, as the numbers were higher than I like to see.

 

[NORMZILLA44]

Randy I don't want to sound like a broken record, but I am a big fan, great saw choice, great work! P.S You think the cylinders are still as high quality as the Mahle?

 

[booger1286]

Hold up there. Raising the exhaust is very necessary on MOST saws I build.

The new 660 just has too much exhaust timing from the factory to be able to raise it........it benefits from less exhaust.

Just asking for help and opinion here. If you take a cylinder and just raise exhaust without changing transfers, wouldnt you just be losing torque no matter what the exhaust timing is. My understanding during blowdown your just building up pressure that is acting against rotation of the crank until transfers open?

 

[tree monkey]

gee randy where did you get the idea for this?
iv'e been doing this style of mod for 10 years and you take the credit.
what a guy

 

[mopar1rules]

Randy I don't want to sound like a broken record, but I am a big fan, great saw choice, great work! P.S You think the cylinders are still as high quality as the Mahle?

I know I'm not Randy, but felt like stating my opinion........I think the Stihl labeled cylinders, fall behind a Mahle labeled cylinder. Casting finish inside the ports and proper port chamfering are found on Mahle labeled cylinderz. My Stihl labeled 660 cylinder had little to no port chamfering. IMO, the kolbenschmidt cylinderz are worse for quality. Them remind me of cheap aftermarket crap.

 

[Jacob J.]

gee randy where did you get the idea for this?
iv'e been doing this style of mod for 10 years and you take the credit.
what a guy

My grandfather was doing all this back in the 50's & 60's. How about them apples?

 

[blsnelling]

The only thing I saw Randy take credit for was making these saws run like they do. And, he did a good job of that.