Who knows the answer to this question?

MBMANIAC

New Member
Jun 14, 2017
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Hello! I'm new to this forum & motorbiking in general & I could use some info & advice. I have a 66cc 2015 Grube Gt5a Skyhawk & I plan on ordering a cylinder & piston so I can see if I'm capable of porting & polishing them correctly. First I need info on what size to order? All I know is the intake manifold is 40mm. Can anyone provide the specs on the motor? I could also use the size of the cylinder & piston? Thx
 

chmn22s

New Member
Jun 8, 2017
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A type piston I think? with the high piston pin and longer con rod. pretty sure it's 47mm
 

MBMANIAC

New Member
Jun 14, 2017
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A type piston I think? with the high piston pin and longer con rod. pretty sure it's 47mm
I did see that the one jug with the 40mm intake also had a 47mm measurement along with it. Like I said I'm a newbie so I really don't know.
 

MBMANIAC

New Member
Jun 14, 2017
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lots of different things out there now, best to take it apart and measure well
I hoped that a reader would of known already because it'd be great to keep everything together, it's my transportation to and from work. Ordering the parts and porting everything while my bike is still running is the plan, need to do more research.
 

crassius

Well-Known Member
Sep 30, 2012
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47mm is most likely what you have - if you lift the barrel just a bit, you can measure distance from bottom of wristpin hole to bottom of piston - port mapping measurements may not be needed if you're going to modify the ports anyway
 

MBMANIAC

New Member
Jun 14, 2017
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O
47mm is most likely what you have - if you lift the barrel just a bit, you can measure distance from bottom of wristpin hole to bottom of piston - port mapping measurements may not be needed if you're going to modify the ports anyway
ok that makes sense. I decided to order the cylinder & piston package from Grubee, figured I couldn't go wrong.
 

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