Saw builds

[Brewz]

Looking at the specs, it 61cc, 44mm bore and 40mm stroke.
Most other 50 to 70cc saws have 34 to 36mm stroke.
Saws dont tend to get up into the 40mm stroke range until you get into 90cc territory.

So its got a really long stroke for its bore size.
How might this affect port timings?
I am now thinking that using timings that work on most saws may not be so great on this saw. Its operating proportions are much different and that has to have some effect.

 

[Iron.and.bark]

Its a nice little saw.
Basically a small 076 with points.

What makes it different to other saws when it comes to intake timing mate?

Probably not the best way to describe it, but it can cause the fuel to spit back out of the carb badly.

If you want a mildly chipped on intake and lower transfers cylinder to experiment with, can have for cost of shipping.

 

[drf256]

Looking at the specs, it 61cc, 44mm bore and 40mm stroke.
Most other 50 to 70cc saws have 34 to 36mm stroke.
Saws dont tend to get up into the 40mm stroke range until you get into 90cc territory.

So its got a really long stroke for its bore size.
How might this affect port timings?
I am now thinking that using timings that work on most saws may not be so great on this saw. Its operating proportions are much different and that has to have some effect.

I'm betting you'll want a numerically higher/physically lower exhaust roof. It should open sooner than a shorter stroke motor of the same rough size. So a port in the same physical location should open at less degrees of crank rotation with a longer stroke motor. The piston moves a further distance for each degree of crank movement.

 

[Brewz]

Perhaps it has a larger capacity case and the high intake is needed to get good case pressure up before the transfers open?
There has to be a reason its so high.

She is in good nick
here is the ignition as it was under the flywheel.



And the badge of honor!

 

[Brewz]

Probably not the best way to describe it, but it can cause the fuel to spit back out of the carb badly.

If you want a mildly chipped on intake and lower transfers cylinder to experiment with, can have for cost of shipping.

Na should be right.
I am thinking with the longer stroke/bore ratio, your bang on the money. I had alarm bells ring when I saw how much needed to be taken off for the intake to be where it should be on a shorter stroke motor.

 

[Iron.and.bark]

Make sure you clean those points (under the black cover). Rotate base plate against crank rotation direction to advance the timing.

 

[Brewz]

I'm betting you'll want a numerically higher/physically lower exhaust roof. It should open sooner than a shorter stroke motor of the same rough size. So a port in the same physical location should open at less degrees of crank rotation with a longer stroke motor. The piston moves a further distance for each degree of crank movement.

It has me thinking. I am still trying to wrap my head around why the port timings are so much different on longer stroke saws.
My 2100 with 44mm stroke was similar.

The port timings are not distance but degrees of rotation so the only difference I can see is that the piston will be moving further which will give a high piston velocity at any given RPM compared to say, an 026 with a 44mm bore and 32mm stroke.

Perhaps the added piston speed is causing the spit back and lowering the intake makes it worse because the added distance and velocity builds higher case pressure?

 

[jmssaws]

I'm grinding on a pretty 064 for @trooney
Should have it finished around dinner.

What bar will it run freind?

 

[trooney]

24". I like to hear that! Did you change out the oiler worm gear?

 

[jmssaws]

24". I like to hear that! Did you change out the oiler worm gear?

24" is what I like to hear.
That's a big 10 4 on the worm gear.

Any problems for you starting a saw that's going to kick?

 

[trooney]

Got to grease my joints!

 

[Brewz]

Go hard or go home!

 

[Brewz]

What are you doing with it Jay?
My 064 came out at 170 psi cold with new rings after 10 from the squish and 20 from the base and is easy to start with a .015 advance.
You do have to be confident with it though, hence the go hard or go home

My 111cc 076 at 180psi fresh will rip your fingers off if your not super confident.
It bit me the other day with oily fingers and it hurt. I pulled it like it was an 026 and it hurt me.
Had another go with stinging fingers and it bit me again.
I grabbed the handle again after cussing a bit and found myself scared of pulling the cord for the first time ever.

I went and washed my hands, wiped down the handle and had to push past some real serious mental resistance to pull it again.

I said to myself....... "ALL IN *b-word" and off it went.

Disrespect a strong saw and it will bite you

 

[jmssaws]

030 from both and depending on where timing is after that I'll do around 102 123 76-78

 

[Brewz]

Nice!
That's where mine is bit with slightly lower compression.
I kicked it up today in the garage and damn it sounds good. It sounds like it wants to go, like its champing at the bit compared to stock.
*s-worde weather here at the moment so not been able to run it an anger but will be doing some fencing next week. might bolt the auger to it and see how fast I can drill a post

 

[jmssaws]

They got the good out of this one

 

[smokey7]

Holy crap that jug is wasted

 

[jmssaws]

Holy crap that jug is wasted

I knew it would be but not that bad,it still ran just not well.

 

[smokey7]

Makes you wonder how many hours caused that or how much crap invested could wear plating like that. Had to take several pistons I'd bet.

 

[Brewz]

They got the good out of this one
View attachment 29669 View attachment 29670

Blue oil, green oil or red?

Ahh I see the problem, probably had all the screws come loose