066 with 385xp piston

Chainsaw Jim · Mar 17, 2018

Here's the beginning numbers with stock ports, but with the squish cut to within .050 of the plug to compensate for the taller piston crown. There is a 3mm spacer gasket also in play.
Ex- 100
Tr- 130
In- 75

I'm not trying to force this concept on the saw. I ended up with a 660 jug that someone hacked up in an attempt of building a race saw. It is no longer useable with either a stock or 288 piston and figured if I were to save it then this might be the only way. I found a way of making the lowers work together with the piston, so that might not be much concern.

Torque monster? Gutless waste of time?
I know I could just build it and find out, but I wanted to share the idea from the beginning and not just say "look what I did".
Please share your opinions, theories, or knowledge.

Stihlbro · Mar 17, 2018

Can you post some pictures of the piston in the bore at bdc and tdc for reference? I am assuming the ports are too wide to use oem or 288? I am intrigued by the thinking out side of the box or the challenge of making something work again.

Joey

Adirondackstihl · Mar 17, 2018

Chainsaw Jim · Mar 17, 2018

Stihlbro said:
Can you post some pictures of the piston in the bore at bdc and tdc for reference? I am assuming the ports are too wide to use oem or 288? I am intrigued by the thinking out side of the box or the challenge of making something work again.

Joey

The exhaust was taken too wide and freeports all the way up and down by a good .030" on one side.

Chainsaw Jim · Mar 18, 2018

This is going to be interesting.

It's looking like it has quite a tunnel without the windowed piston.

mgr1 · Mar 18, 2018

There is a lot removed from the piston. Is it safe or is it for trying?

Chainsaw Jim · Mar 18, 2018

mgr1 said:
There is a lot removed from the piston. Is it safe or is it for trying?

There's more than enough meat still left on it. When you see enough different pistons from saws in that size range and how they're made you'll notice these husky ones are exceptionally heavy. Skirts may rub a little but they aren't a load bearing portion of the piston.
I don't believe it will fail.

mgr1 · Mar 18, 2018

Looking forward to see it run.

drf256 · Mar 18, 2018

Love the ingenuity Jimbo. You were given a sow’s ear.

I see case volume increasing from tunnels and decreasing from piston. My guestimometer puts you at slight increase.

How do you plan on managing the compression increase from the tiny chamber you have now? Can always add a second angle.

Chainsaw Jim · Mar 18, 2018

drf256 said:
Love the ingenuity Jimbo. You were given a sow’s ear.

I see case volume increasing from tunnels and decreasing from piston. My guestimometer puts you at slight increase.

How do you plan on managing the compression increase from the tiny chamber you have now? Can always add a second angle.

It's a decomp jug if by managing you mean starting.

Chainsaw Jim · Mar 18, 2018

Here's the exhaust as I received it.

Here's a bit of a new look.
I'll be running one ring.

Intake roughed in..

I think I've fallen asleep three times trying to get this last post finished before I hit the sack. Lol
I'll be back at it later this afternoon to finish it up.

Redfin · Mar 18, 2018

Did you take off the lower trans or did you get it that way?

Deets066 · Mar 18, 2018

Redfin said:
Did you take off the lower trans or did you get it that way?

Looks like in the last few pics only one of em was ground in.

Redfin · Mar 18, 2018

All the pics show it that way.

Chainsaw Jim · Mar 18, 2018

Redfin said:
Did you take off the lower trans or did you get it that way?

Thats my doing. I'll be matching the other side today when I get rid of this damn headache that started two nights ago.

Adirondackstihl · Mar 18, 2018

Chainsaw Jim said:
Thats my doing. I'll be matching the other side today when I get rid of this damn headache that started two nights ago.

Hate that!
Advil and Mountain Dew always seem to help mine. Not a Dew fan, but the sugar helps

RI Chevy · Mar 18, 2018

I understand that if you drink Mt. Dew and monkey around working on saws, they run faster and stronger. Lol

Wagnerwerks · Mar 18, 2018

Are you trying to turn this into the next oil thread? Cause I like Dr pepper....

RI Chevy · Mar 18, 2018

Maybe we need a soda pop thread? Lol

Adirondackstihl · Mar 18, 2018

Wagnerwerks said:
Are you trying to turn this into the next oil thread? Cause I like Dr pepper....

Gross!! That’s equivalent to orange bottle Stihl oil

066 with 385xp piston

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