066/MS 660 port #'s. Please share your stock #'s

[big t double]

To the guys that have experience porting these saws: how does the amount of blowdown affect how they run? That seemed to be the biggest difference in the red light 066 and stock 660 cylinder. Deets ported o66 jug, which has a decomp, has closer blowdown numbers to the red light.

Edit: for what it's worth the red light cylinder was a kohlbenschmidt

 

[blsnelling]

The correct blowdown is super important is making a saw run like you want. 32° of blowdown is just ridiculous, IMHO. This isn't a pipe saw, lol.

 

[blsnelling]

I had a flat top non redlight non decomp mahle 066. It was at 97-119-80 stock.

I bet that one ran well.

 

[Deets066]

Blowdown on my 066 and teds red light was 25 the 660 was 30

 

[blsnelling]

Blowdown on my 066 and teds red light was 25 the 660 was 30

Even 25° is too much for my taste.

 

[Mastermind]

I get the MS660 jugs down to 98 usually.

 

[big t double]

Even 25° is too much for my taste.

So how would too much blowdown affect how the saw runs?

 

[blsnelling]

It won't turn the RPMs I want. Of course, you can go too high too.

 

[Deets066]

So to you porters, if you had numbers like mine 97-122-81 what route would you go for porting?

 

[komatsuvarna]

I bet that one ran well.

It run OK. I ported it and got 8th at the 066 buildoff IIRC. My 372xpw I had at the time was a second faster in the same cant with the same 32" bar and chain lol. Of course cutting a cookie with a 32"bar on a 70cc is different than working with it.

A guy in Louisiana bought that saw. Talked to him not long ago and it was still going strong. Other than a set of clutch springs he hadn't touched it.

 

[Mastermind]

So to you porters, if you had numbers like mine 97-122-81 what route would you go for porting?

I'd cut the squish to get the exhaust down to 100, then set the transfers at 118, and leave the intake port untouched.

 

[Deets066]

Squish and base have been cut but only .030, thanks for the input

 

[blsnelling]

I'd cut the squish to get the exhaust down to 100, then set the transfers at 118, and leave the intake port untouched.

I like those numbers. I still need to go back in my 064/066. All I probably need to do is cut the squish band and replace the popup piston. That would probably put me right where I need to be.

 

[Mastermind]

Squish and base have been cut but only .030, thanks for the input

You can take up to .070 out of the squish band on a 660 without the piston free porting in the exhaust.

 

[blsnelling]

I like those numbers.

Squish and base have been cut but only .030, thanks for the input

That one must have had a real high exhaust. Like Randy talks about, that's just counterintuitive for a big work saw intended for long bars.

 

[Mastermind]

I like those numbers. I still need to go back in my 064/066. All I probably need to do is cut the squish band and replace the popup piston. That would probably put me right where I need to be.

On the 064, I'd set the exhaust at 100, the fingers at 116, and the mains at 118.

 

[blsnelling]

On the 064, I'd set the exhaust at 100, the fingers at 116, and the mains at 118.

You trying to stretch my wings? I've still not ventured into fingers. I thought you were just connecting the lowers to the uppers. No?

 

[big t double]

Do you finger port all 064's. Man that just adds another variable to us slouches that are trying to get a grasp on port timing numbers hahaha. Do you remember if you added fingers to my 064...or bridge ports...I remember you saying you add bridge ports to all 1122 saws...or more specifically..non quad transfer jugs

 

[Mastermind]

I don't finger port many saws. Only a few really.

I do like them in some models very well though. The 064 jug is plenty thick, and that makes it a great one to grind them in.....

I just used bridge ports in your 064 Ted.

 

[Deets066]

I'll get her back on the wheel and see how much I need to take out to get it down closer to 100