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Discussion Starter #1
Time to change the piston and I am a bit confused about the group 1 and group 2 kit.

Some people say the number 1 or 2 is marked on the engine to tell you which you need - mine is not stamped with either ( I have removed powervalve cover).

Others say that group 1 is for low hour bikes and group 2 is for bikes which are 100+ hours!

Please can someone explain to me what I will need? My bikes done about 50 hours!

Thanks!
 

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On my '06 250exc piston size was stamped on machined face under LH PV cover.

Personally I would take off the head to see what size piston I had in just now and remove barrel and size it to see what size of piston was needed.

 

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Mines wrote on the barrel on the left hand side but mine's an exc 400 so im sure yours will be wrote somewhere else (see PeePod's post), one thing i do definitely no is that when you get the piston that's in there now out it will also be stamped on the top of that,I was told the different sizes are to do with the very fine tolerances in the manufacturing process?? Kev will tell you 100% when he comes along ;0)
 

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On the sx 250 there is an '1' or '2' stamped on the top of the piston at the back side. i only know because i bought the wrong one to start with, thinking that it hadn't had a piston before so it must be the "smaller" 1 piston.(nar it dosen't work like that seemingly!)

oh and if it is a group 1.... i have one for sale !
 

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Discussion Starter #8
On the sx 250 there is an '1' or '2' stamped on the top of the piston at the back side. i only know because i bought the wrong one to start with, thinking that it hadn't had a piston before so it must be the "smaller" 1 piston.(nar it dosen't work like that seemingly!)

oh and if it is a group 1.... i have one for sale !
Thanks matey!

Just spoken to the shop and they have confirmed that this is correct!
 
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