Author Topic: Sachs Dolmar 166 big bore  (Read 467 times)

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Offline Uncle Lee

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Sachs Dolmar 166 big bore
« on: November 06, 2014, 08:11:18 am »
Not sure if this is in the correct forum. Kev you move it if you wish.

This is a project i had been thinking about for awhile. I previously sent a 166
cylinder to US Chrome to have it replated but they couldn't do it do to a groove
that went right to the top. They said they could bore it over size. So i sat on it
for over a year and then i purchased another 166 basket case. Thought now
whould be a good time to think hard about using this damaged cylinder. I did
some basic research with optional pistons and found the Stihl 084-088 piston
would be the easiest to make work and would be giving me a 4mm overbore.
Bought an aftermarket piston from Randy. Now the work. The 184 has a taller
crown hight and 13mm pin. 166 has a 14mm pin. I found a local small machine
shop that offset bored the pin hole the 14mm and .017 offset. That lowered
the piston and put me where i wanted with plenty of squish. Next move was
to add to the exhaust side piston skirt as when the piston was at tdc it uncovered
the port. So i welded aprox 3mm to the piston skirt. Next i assembled the saw
and ran it with a stock unmodded 166 muffler. She ran great and is 8 seconds faster
than a identical 166 with same B+C. Both saws cut in the same log on the same end.
Both saws matched as close as i could get and the big bore is 8 seconds faster.
But i still had a feeling there was more to get out of it. I then realized i didn't do
anything to the intake skirt. It is closing the intake much later than the stock 166 so
i took it appart and welded the intake side to match the 166. I probably didn't have
to go that far and will take some off later. I also had a not so nice muffler so i did the
double barrel muffler mod. Ran it in the same log again and gained almost 4 seconds.
Thats almost 12 seconds over stock. Saw seems to pull like a freight train. The next
step will be to advance timing a couple degrees and take maybe 1mm off the intake
skirt to give me a bit more duration.
Keep in mind guys i'm no porter at all and a complete rookie at modding saws but this
one i'm very pleased with so far.



Uncle Lee











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Offline Uncle Lee

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Re: Sachs Dolmar 166 big bore
« Reply #1 on: November 06, 2014, 08:14:22 am »
First video with stock muffler and untouched intake side skirt.



Uncle Lee


Offline Uncle Lee

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Re: Sachs Dolmar 166 big bore
« Reply #2 on: November 06, 2014, 08:16:07 am »
Second video with welded intake skirt and modded muffler.


Uncle Lee




Offline aclarke

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Re: Sachs Dolmar 166 big bore
« Reply #3 on: November 06, 2014, 08:52:04 am »
Very nice work!

Offline mdavlee .

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Re: Sachs Dolmar 166 big bore
« Reply #4 on: November 06, 2014, 10:45:50 am »
Nice job as always Lee. I believe this fits in this area.

Offline 660magnum

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Re: Sachs Dolmar 166 big bore
« Reply #5 on: November 06, 2014, 10:58:36 am »
Good job
We should share what we know... someone may learn...
That knowledge can live after us... and that "Pays It Forward".
Be all that you can be . . .

Offline Uncle Lee

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Re: Sachs Dolmar 166 big bore
« Reply #6 on: November 06, 2014, 11:46:40 am »
Thanks Guys
Also forgot to mention that this was stock at 118cc's and now
with the 60mm bore it's at 136cc's. Quite a jump. Compression
is at 185 and not even broke in yet.



Lee

Offline 660magnum

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Re: Sachs Dolmar 166 big bore
« Reply #7 on: November 06, 2014, 12:18:15 pm »
The 166 has been awakened?
We should share what we know... someone may learn...
That knowledge can live after us... and that "Pays It Forward".
Be all that you can be . . .

Offline Cut4fun .

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Re: Sachs Dolmar 166 big bore
« Reply #8 on: November 06, 2014, 12:18:28 pm »
I have liked your thinking on alot of these projects in the past Lee.  8)

That 394 piston idea used for a stocker was cool info too.   ;)
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Offline Cut4fun .

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Re: Sachs Dolmar 166 big bore
« Reply #9 on: November 06, 2014, 12:20:19 pm »
Here or the  Dolmar board is perfect. 
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