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Vetterdog
Vetterdog
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Hi,

anyone have experience with mc forged pistons?
Àre they reconned as good or bad quality pistons ?

thanks


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Forged pistons expand more when they heat up than cast so the initial clearance needs to be more. A buddy has a forged big bore piston in his SR500 Yamaha and it rattles like crazy until the bike is run hard. The only time that engine doesn't sound like the parts are going to fly out is right after a hard freeway blast. This may not be representative of all forged pistons.

Tom Graham

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Hi Rocker,

Do a search on triumph bullentin board on mc forged pistons. John Healy, listed the specs on clearance. As I remember those will expand.

Some forged do not expand as much. Britech has forged that are treated also, and gapless rings. I think it maybe the best solution available.


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I used them in my previous A65 race motor. They held up quite nicely. I used .004" of clearance at the skirt and Hepolite rings.


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MC Forged, made in the USA, is as good a piston as any and better than most (IMO). I have a set for the A10 for which the fol clearance data are given:
"Piston pin - .0005 to .0006 inch. "This is important on all forged pistons". [This is a "free fit"]
Piston [skirt] clearance - .003 for breakin .006 for racing."

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The MC forged pistons made/sold during the '60s-'70s era were good for their time. However due to the low silicon content alloy used 'back then' they expanded a lot when heated up. Because of this they needed to be fit very loose.

Also due to their design they would expand excessively on the sides across the pin boss area. Too late for many of us we found out in later years the piston skirt on the sides should be filed down a couple thou. aarrgh.

'Modern' made forged pistons from JE and Venolia with short skirts and short pins for lighter weight work nicely and are designed properly to deal with the piston distortion due to heat.
BTW, we now fit 85 and 90 mm bore Goldie pistons to 3.5 - 4 thou clearance without a problem. I like that.

I and many other GSrs get our custom designed/made Venolia pistons from Gold Star Ron. He's recently mentioned he has a new batch to put on the shelf. I like that.
FWIW, I also like Total Seal rings....


Dave - NV

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