Author Topic: Sachs Dolmar 166 big bore  (Read 472 times)

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Offline Uncle Lee

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Re: Sachs Dolmar 166 big bore
« Reply #10 on: November 06, 2014, 01:00:49 pm »
Kevin,
I still have that 166 with the 394 piston in it. Been meaning
to put one of the Wiseco piston kits in her but it ran good
with the 394 piston. Boy that was a long time ago.



Lee

Offline Cut4fun .

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Re: Sachs Dolmar 166 big bore
« Reply #11 on: November 06, 2014, 01:08:10 pm »
Kevin,
I still have that 166 with the 394 piston in it. Been meaning
to put one of the Wiseco piston kits in her but it ran good
with the 394 piston. Boy that was a long time ago.



Lee

My memory works like that. Some things are stuck in there and some things just wash away anymore.  :'(

I just always thought that was a cool idea you had when the 166 pistons were scarce.  Boring the pin bosses etc.    :o 8)
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Offline mdavlee .

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Re: Sachs Dolmar 166 big bore
« Reply #12 on: November 06, 2014, 07:29:59 pm »
That was a good solution to a piston that wasn't available.

Offline aclarke

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Re: Sachs Dolmar 166 big bore
« Reply #13 on: November 06, 2014, 09:05:28 pm »
How was your experience with US Chrome?  Heard through the grapevine they've  modernized and are producing a fine finished product.    Have had mixed results with other platers...

Adam

Offline Uncle Lee

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Re: Sachs Dolmar 166 big bore
« Reply #14 on: November 07, 2014, 03:33:09 pm »
The only issue i have had with US Chrome was they did two 166 cylinders
at the same time and both the piston wouldn't go to the top. Must have
had a bad taper or i'm proper bore. They made it good and fixed them.
They have have done about two dozen for me and i'm in good with them.



Lee

Offline aclarke

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Re: Sachs Dolmar 166 big bore
« Reply #15 on: November 07, 2014, 04:27:56 pm »
Lee, thanks. 

Offline 660magnum

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Re: Sachs Dolmar 166 big bore
« Reply #16 on: November 07, 2014, 05:37:15 pm »
I have a model airplane friend in Idaho that makes pistons for small gas two strokes when a suitable example is not available commercially. His work so far has included 30 - 60cc singles and multiple cylinder engines of the same bores.

He has also made up several engines utilizing some commercial parts and some parts he fabricates on his own. His work looks like it is CNC work but it's not.

He has also straightened twisted cranks for me.

Here is a reed valve twin he made up with a custom crankcase and commercially available cylinders/pistons and crank assemblies.



The crankshaft utilized two single cylinder crankshafts adapted together. The finished product looks no different than similar sized commercially available examples.



He's recently made several custom fitted pistons for a line of problem engines. He used 4032 aluminum from McMaster-Carr. I have several in process pictures but they are fuzzy cell phone pictures.

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Offline aclarke

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Re: Sachs Dolmar 166 big bore
« Reply #17 on: November 07, 2014, 06:16:30 pm »
I'd be curious to know what alloy he uses.  I made a number of  pistons out of 7075 T6 but had too many seizure issues. The pistons "moved" a lot from stresses induced during machining and the cyl wall clearances had to sloppy to not seize.    May try it again with a more appropriate alloy like 4032 or 2618 although the latter is nearly impossible to find.

Offline 660magnum

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Re: Sachs Dolmar 166 big bore
« Reply #18 on: November 07, 2014, 06:30:23 pm »
I added the 4032 in my previous post
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That knowledge can live after us... and that "Pays It Forward".
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Offline 604f_1

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Re: Sachs Dolmar 166 big bore
« Reply #19 on: November 07, 2014, 06:36:25 pm »
4032 is the way to go . I have build about 10 of them and still waiting for one to fail . No problem with seizure without any fancy coating on the skirt . Same clearance as stock except i make the portion above the ring .001 smaller than stock . Machines VERY well too .

For those who are not familiar with 4032 , its high silicon aluminum (12%). Silicon reduces expansion , wear and the tendency to stick of low silicon aluminum .

 

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