Author Topic: Who makes good cylinder, piston rings, for 372 and 390xp's?  (Read 2338 times)

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Offline alsled

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Do these aftermarket companies keep the same port timing? or do they change things?

Offline 660magnum

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They are pretty close
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Offline SawTroll

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Do these aftermarket companies keep the same port timing? or do they change things?

Aftermarket cylinders tend to have ports that are narrower, which is a negative factor. I can't comment on the timing, but it likely varies.

Offline mdavlee .

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Timing will vary on the cylinders. Some are as good and occasionally better. I would probably stick with OEM for the 390 since there's not many choices there. You can get an OEM cylinder from spike60 for a better deal than anywhere online. Be worth checking into. I think one of those aftermarket 390 pistons didn't last long for a member in BC. The 372 has a lot of choices and a lot of them seem to be fine. Check with weedeaterman.com for aftermarket parts.

Offline KilliansRedLeo

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Whats the difference between the two pistons?

Both the BB kit piston and the Stihl 064 piston are 52mm. The Stihl 064 piston it taller by approximately 1.3mm and can be used to raise the CR to above 190PSI. I have done several for customers and the saws run well, with no problems so far.

The Stihl piston has the same 12mm pin as the Husky however a few thousandths must be removed from the inner sides of the piston pin boss in order to clear the small end of the rod and you must make sure that you have about 2mm clearance at BDC for the crank throws. A machine shop can remove the metal from the piston, my gunsmith does it for me, quicker and cheaper.
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Offline 660magnum

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I have a 372 set up this way.
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Offline alsled

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190 psi. Can you still run 91 octane pump gas on that?  I do a lot with snowmobiles and they would never live at  190 psi. Lots of detonation, like instantly.

Offline KilliansRedLeo

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Never had a problem. I have customers who run 91 e10 with out a problem also others who run pure gas as well as SEF and no problems yet.
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Offline alsled

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That's good to know. Just wondering, is there a huge difference in 190 and stock compression, as far as torque/ hp, plain old grunt feeling ?

Offline 660magnum

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They sometimes build up more heat.
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