Author Topic: Who makes good cylinder, piston rings, for 372 and 390xp's?  (Read 767 times)

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Offline KilliansRedLeo

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Normally, when I do one of these BB/Stihl saws I also do a dual port muffler which seems to control the 'run hotter' situation. I have even been known to substitute the carb off a 372XT (Walbro RWJ-4) or the carb off a 390XP, both are bigger than stock but you would only note a difference on a stopwatch. In order to change to either of these 'Tillotson' mount carbs the intake setup has to be changed, not hat big a deal but a PITA to find all the correct parts.
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Offline alsled

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Well i bought a 52 mm hyway BB kit for a 365.  Plus a sthill 064 meteor piston

I posted these two pics show the difference in height, the meteor is about .015 taller in this case, not 1.2mm  Quality controll issues Tim, as you found yours to be 1.2 mm different?? about .047




Offline KilliansRedLeo

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It appears that you are comparing the BB piston to the Stihl piston. When I quoted 1.2mm I was comparing the stock 372 Mahle piston to the Meteor Stihl 064.

"When the people fear the government...you have tyranny....When the government fears the people....you have liberty"

Thomas Jefferson
1743-1826

Offline KilliansRedLeo

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Here are the specs for the Meteor replacement for the standard 372 Husqvarna piston:
 
Fits the following chainsaws:
Husqvarna 371, 372*
Jonsered 2071, 2171

Note This is a single ring piston, 372 EPA saws come with a pair of (50x1.2mm) rings. This piston will fit the the two ring models
Replaces Part Number 503 69 12 71

Bore 49.96mm
Height 42.5mm
Head Type Flat
Piston Pin 12mm x 36mm x 8mm
Ring 50mm x 1.5mm (Caber F-Cast GH.F)
Compression/Pin Top to top of Piston 16.5mm
Compression/Pin Center to top of Piston 22.5mm

Here are the specs for the Meteor replacement for the Stihl 064 piston

Fits the following chainsaws:
Stihl 064, MS 640

Replaces Part Number 1122 030 2001

Bore 51.96mm
Height 43mm
Head Type Flat
Piston Pin 12mm x 33mm x 8mm
Rings 52mm x 1.5mm (Caber F-Cast GH.F)
Compression/Pin Top to top of Piston 17mm
Compression/Pin Center to top of Piston 23mm

Depending on your numbers your may be able to get optimal squish and not have to use a base gasket.
"When the people fear the government...you have tyranny....When the government fears the people....you have liberty"

Thomas Jefferson
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Offline alsled

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Tim, 

Well I put the big bore kit on, no base gasket and the 064 meteor piston, squish came out at .022, I tried doing a compression check but almost knocked myself out, I'm at 180 with the decompression valve open.  I'll be dis- assembling and installing a .015 base gasket on Sun.

I know you said 195 is where they really run good, but how the hell do you start it?

This BB kit is on the 365 special I brought from you.

Offline KilliansRedLeo

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Well, your a bigger guy than I am, I have the same saw and I can start it without problem. 200psi is a lot, but it only takes a couple of short pulls to get mine going! Check your timing.
"When the people fear the government...you have tyranny....When the government fears the people....you have liberty"

Thomas Jefferson
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Offline 660magnum

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I have a 372 set up this way with the Meteor 064 piston and for an old man I don't have any trouble starting it. The saw runs strong.
We should share what we know... someone may learn...
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Offline KilliansRedLeo

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Grit your teeth and get the saw running, get it to idle, then let it run until it runs out of gas. After that it should be easier to start.

Nobody ever said that a high performance saw was going to be a 'home owner' cake walk saw to start.
"When the people fear the government...you have tyranny....When the government fears the people....you have liberty"

Thomas Jefferson
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Offline KilliansRedLeo

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660, +1, I am also an 'old fart' and have no problems either. These are really good running saws! I think Al will be fine as soon as he gets used to the saw and its starting quirks.
"When the people fear the government...you have tyranny....When the government fears the people....you have liberty"

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Offline alsled

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Tim and 660,  question for you both.  Are either of you using a base gasket or copper shim?   And what is the squish on your saws? 

Also, I did not try to start it yesterday, wanted the gasket in a tube to set up before fuel gets at it.

 

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