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Author Topic: FP40 Question  (Read 1378 times)

Offline RDJeff

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FP40 Question
« on: November 09, 2011, 09:30:44 PM »
I just picked up my sixth FP40 on the auction site, and this one is different from the others in that there is a hole in the piston skirt.  What have I got here?  The hole is about 1/4" in diameter, and appears to be machined that way.  I can see the rod ond pin through the hole.  I'm used to older two-stroke motorcycles having holes in the piston skirts, but they are in the intake face, while this is visible throught the exhaust port.  Interesting...
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Offline Curtis Shipp

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Re: FP40 Question
« Reply #1 on: November 10, 2011, 06:25:35 AM »
Piston in backwards.
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Offline RDJeff

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Re: FP40 Question
« Reply #2 on: November 10, 2011, 12:15:24 PM »
So, why didn't I think of that? ???
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Offline Geoff Goodworth

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Re: FP40 Question
« Reply #3 on: November 12, 2011, 04:50:41 PM »
I have several FP 40s—both steel liner and ABN—and the only holes in the piston are for the wrist pin. None have a hole in the side of the piston.

I'm going to guess that it's been modified and the piston is in back to front.
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Offline Dennis Moritz

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Re: FP40 Question
« Reply #4 on: November 13, 2011, 07:06:21 AM »
Not stock. FP pistons don't have that hole.
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Offline RandySmith

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Re: FP40 Question
« Reply #5 on: November 13, 2011, 03:40:04 PM »
Quote from: Dennis Moritz on November 13, 2011, 07:06:21 AM
Not stock. FP pistons don't have that hole.

Yes FP pistons  did have that hole from OS in early motors

Randy
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Offline RDJeff

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Re: FP40 Question
« Reply #6 on: November 14, 2011, 09:53:41 AM »
It looks like I need to take apart some of my FPs in order to see what's what! 

Randy, if the hole is standard on older engines, do you think my piston is in backwards?

Thanks everyone for the responses!
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Offline RandySmith

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Re: FP40 Question
« Reply #7 on: November 14, 2011, 10:21:57 AM »
yes  the piston is more than likley in backwards, check the rod also if it has one side of the bottom "chamfered" put it toward the crankshaft

Randy
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Offline RDJeff

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Re: FP40 Question
« Reply #8 on: November 16, 2011, 09:41:35 AM »
Thanks Randy, I'll give it a look!
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