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Old 02-20-2015, 10:03 PM
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mapbike mapbike is offline
Motorized Bicycle Elite Member
Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: Curious about the engine, :question:

that piston is a high bin piston, which is what is found in the GT5 geometry type engines that has a 114mm length rod.

That piston needs to be used along with a lower that has either the FM80 rod or the ZAF rod the engines with a ZL rod or a ZAE50 rod are the 110mm rod engines and that piston wont work with them because the piston skirt will hit the crank when it rotates down toward BDC.

if the lower you have has a FM80 rod then that is the correct piston for it and you will need to either get a cylinder for a GT5 engine or have a good bit shaved off the deck of a PK80 cylinder that was designed for the 40mm stroke engine.

there are a few sellers on ebay that sell the correct jug for your piston and lower set up, Ill post a link to a complete GT5 top end kit for $30 shipped here in a bit when I have the time.
I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!

Last edited by mapbike; 02-20-2015 at 10:08 PM.
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