Author Topic: Black Piston  (Read 615 times)

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Offline mdavlee .

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Re: Black Piston
« Reply #30 on: September 30, 2017, 03:14:09 am »
Way way too rich
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Offline dpjones

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Re: Black Piston
« Reply #31 on: September 30, 2017, 11:11:42 am »
OK Thanks, I'll put it on 13,000.

Offline Cut4fun .

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Re: Black Piston
« Reply #32 on: September 30, 2017, 07:35:33 pm »
Way way too rich
OK Thanks, I'll put it on 13,000.

Mike isnt 13K max for stock  660 or is it 13.5K?

http://www.madsens1.com/saw_carb_tune.htm

Found this tidbit pm 650 660. * max RPM for carburetors without limiter caps is 13,000.  max RPM for carburetors WITH limiter caps is 13,500, according to workshop manual from 2007. 

stock stihl 066 shows 13K max

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Offline mdavlee .

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Re: Black Piston
« Reply #33 on: October 01, 2017, 01:23:31 am »
13.5k is safe. I've had them a touch over 14k stock with open muffler. 12.8-13k for milling or blocking big trees
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Offline dpjones

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Re: Black Piston
« Reply #34 on: October 01, 2017, 12:04:54 pm »
With this tach of my friends this saw will only turn up to around 12,000 and that's without 4-stroking.

Could this be the a/m big bore kit or the tach? My 026 shows over 11,000 before it 4 strokes.

If it's port timing I'll leave it be for now. When I put it on all I did was a little beveling to the ports.

If it matters, I put on a new wj-76 and the muffler is hollowed out, no cage.

Offline jmester

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Re: Black Piston
« Reply #35 on: October 01, 2017, 03:48:34 pm »
I would have to say that it is your tach. Where is your high speed screw at. Is it close to 1 turn out from a lightly seated position. Also do you have an aftermarket ignition module. Port timing has more to do with where the saw makes peak power under load then max rpm out of the wood.
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Offline dpjones

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Re: Black Piston
« Reply #36 on: October 01, 2017, 06:57:13 pm »
The high side screw is 7/8 or real close, low is 1, the ignition module is farmertech, only thing that is name brand is carburetor. It was a kit saw, I just don't want it to end up like the one in the picture at the first of the post

I'm sorry if I lead anyone to think it was a true stihl. it's just a copy

Didn't know that about the timing, just figured cheap parts, get what you pay for.

I'm going to get a good tach, just not sure which one.

I really appreciate everyones help.

Offline jmester

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Re: Black Piston
« Reply #37 on: October 01, 2017, 08:37:39 pm »
If you get a new tach and it still will not come up to at least 13,000 with the high speed screw around one turn out. I would look into another Ignition Module. I had some problems with the aftermarket ignition module on a husky saw it would not let it make full rpm.
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Offline dpjones

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Re: Black Piston
« Reply #38 on: October 01, 2017, 10:10:12 pm »
I've got a 026 and a 029 Stihl brand module, not sure if they are the same. When it gets around 11,000 it don't miss it seems like my 78 chevy truck with the time pulled back too far

Offline trappermike

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Re: Black Piston
« Reply #39 on: December 29, 2018, 05:39:35 pm »
Synthetic 2-stroke oils started in the 70's when I was fixing motorcycles,some were very expensive and highly regarded but I noticed many times on looking at a piston run on it for a long while the piston would be totally black,even the underside. I would suggest going to a good quality mineral oil.
Another more common cause for a black piston,often in very short running time is caused by a far too restrictive muffler,causing the burned oil smoke to be held back and it re-condenses as burnt oil on the piston.
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