Stripping down a Shindaiwa 757 and possibly destroying the cylinder

[Matt Hogden]

My 757 is only 18 months old and i thought i might do some mods to it.
I have already woke it up by doing a muffler mod, but modifying the base of the cylinder is something i have been wanting to do since i first got it. I have searched the internet for mods for this saw, but there is just not enough info out there.
I port motor cycles for a living at a performance shop and this is my first attempt at a saw. So my understanding of saw basics is very limited.
There is a real chance i have destroyed this beautiful cylinder.
But i should have it back together in the next few days and then we will see!

Sent from my SM-G930F using Tapatalk

 

[Matt Hogden]

Oh and i am going to probably run NO base gasket as well. Even though this saw runs a "Hemi" style combustion chamber and piston

Sent from my SM-G930F using Tapatalk

 

[JonCraig]

I don't understand this (but I've never done any porting...). Basically opened up the lower transfers big time?

 

[Matt Hogden]

Yeps, and matched the transfers to the cases. And widened the exhaust, and cleaned up the intake.

Sent from my SM-G930F using Tapatalk

 

[Little Al]

Yeps, and matched the transfers to the cases. And widened the exhaust, and cleaned up the intake.

Sent from my SM-G930F using Tapatalk

In regards to the base gasket have you measured the squish? as you don't mention that you have

 

[Matt Hogden]

Yeps mate sure did. Its at 040 so thats plenty safe.

Sent from my SM-G930F using Tapatalk

 

[Matt Hogden]

UPDATE
I got it back together and it runs!
It revs up and idles well. Although it now seems really rich on the high needle. But i dont have the bar back in it yet. So i will do so tomorrow and then push it into some hardwood and give it a tune.
.
So far everything is progressing well [emoji106]

Sent from my SM-G930F using Tapatalk

 

[blsnelling]

It seems really odd to me how the case is made to feed the transfers, then the cylinder skirt blocks it off. What you've done makes perfect sense to me. I like your bold yet calculated approach.

 

[Matt Hogden]

Thanks mate

Sent from my SM-G930F using Tapatalk

 

[Matt Hogden]

Holy crap!
I just tuned this thing and did my first few cuts into some Australian "Ironbark" hardwood.
This thing is an ANIMAL now!
I CANNOT overstate how much power this thing has now!
My cousin rolled up with his Dolmar 7900 and we did some testing together and we both agree that the power was on par!
Hows that for a power increase!.
So,
Torque = massive increase
Rpm = Definite mild increase
High rpm power = WAY up!

Sent from my SM-G930F using Tapatalk

 

[Matt Hogden]

This weekend I will be cutting about 4 tonne of ironbark. I cant wait!

Sent from my SM-G930F using Tapatalk

 

[Matt Hogden]

Well i just got home from cutting firewood all weekend. Put 4 tanks through her.
She was awesome. It has heaps more grunt and definitely has more top end power as well. It ran awesome. I had a another friend try it out and he was very impressed. He has a 660 magnum. And even though the power was no where near 660 sort of power, he was very impressed with the power it has for only 73ccs.
Great mod for 757 owners!

Sent from my SM-G930F using Tapatalk

 

[CR888]

The 757 on the bench stripped down looks to be such a well made saw. Its funny a farm grade farm boss would often fetch more money. Good job!

 

[Matt Hogden]

Mate these Shindaiwas are built like tanks

Sent from my SM-G930F using Tapatalk

 

[drf255]

Great stuff.

I'm not understanding why the case has the scalloped cutouts to feed bottom fed transfers but has side fed transfers.

Was this same case used on other models?

I woulda thought the increased case volume woulda made the saw a slug. Evidently not.

 

[pastryguyhawaii]

I'd like to see how that runs. I just got a 757 and they are solid saws stock. How's that air filter setup work for you down there?

 

[Matt Hogden]

I love the airfilter system. It think its great.


Sent from my SM-G930F using Tapatalk

 

[Matt Hogden]

I dont think these cases were generic to other models. But my mods sure have woke it up

Sent from my SM-G930F using Tapatalk

 

[LegDeLimber]

Matt, Is the piston windowed or solid?
I've got a couple of Echo, backpack blowers here and the they have *bottom fed*, closed, quad port cylinders.
The pistons are closed side types.

One of these Echos has massive "chamfering" (trenching is a more accurate word) around the exhaust port. An easy 6~8 degrees of duration beyond what the port channel seems to have been intended to be.
I can see that Shindaiwa division gives the deburring crews nothing but a ball cutter also!

 

[Matt Hogden]

Yeps the piston is closed mate. Seems that Shindaiwa arent interested in maximum horsepower

Sent from my SM-G930F using Tapatalk