Sherco Top End Engine Rebuild Kit - 125cc - 2012 > 2013

Part Number
RKTS2011125
Grouped product items
Product Name Price Qty
S3/Vertex Replica Sherco 125 Piston Kit Size A
0 in stock - Available to order
£154.95
S3/Vertex Replica Sherco 125 Piston kit Size B
1 in stock
£154.95
Vertex Replica Sherco 125 Piston kit Size C
1 in stock
£107.95
Vertex Replica Sherco 125 Piston kit Size D
0 in stock - Available to order
£107.95
Sherco Cylinder Gasket 125cc 0.5mm
1 in stock
£6.12
Sherco Cylinder Gasket 125cc 0.4mm
1 in stock
£8.28
Sherco Cylinder Gasket 125cc 0.3mm
1 in stock
£3.84
Sherco Cylinder Gasket 125cc 0.2mm
1 in stock
£2.52
Sherco Outer Cylinder Head O-Ring Large
112 in stock
£4.98
Sherco 125 Inner Head O-ring - 2012 on
14 in stock
£4.08
Sherco Cylinder Head O-Ring For Bolts
308 in stock
£0.69
Cylinder Exhaust Gasket - Sherco 1999 On, Scorpa 2010 On
12 in stock
£4.55
Exhaust O-ring - Sherco 1999>2013, Scorpa 2010>2013
45 in stock
£2.99
Aluminium Flat Seal Crush Washer - M5x9x1
261 in stock
£0.30
Little End Bearing 16x20x20mm
7 in stock
£14.99
Top end rebuild kit including the piston, gaskets and O-rings

For the Sherco ST125 trials bikes from 2011 to 2013.

Please select the piston and base gasket size required to suit your bike, each bike is different.

Piston Sizes

LetterSizePart number
A 55.95mm M212
B 55.96mm M580 or M212B
C 55.97mm M581 or M212C
D 55.98mm M582 or M212D


The factory recommended piston to cylinder tolerance for the 125 is 0.0175 to 0.0225mm (we aim for a more realistic 0.02 to 0.03mm), if you are considering putting the next size up piston in please be aware that your original piston will have worn down and any wear in the cylinder is unlikely to be uniform down the bore so please check the bore size all the way down the cylinder and from left to right as well as front to back, the factory measure the piston and cylinders at 24 degrees C. The piston is measured front to back and 19mm up from the bottom of the skirt, be aware that the pistons are manufacture tapered (larger at the bottom) and oval (larger front to back) to allow for unequal expansion of the piston in use.


16mm Gudgeon Pin by mm long
Centre of the gudgeon pin to the top edge of the piston mm
Overall height mm
Weight including rings, gudgeon pin and C-clips  grams

The base gaskets are available in different thicknesses to allow the correct squish clearance to be achieved. The standard gasket is 0.5mm thick and is commonly used with one of the thinner shim gasket, some bikes even come from the factory with 3 gaskets.

The factory recommend you set your squish (the gap between the top edge of the piston and the cylinder head) to a minimum of 0.50mm.

More Information
Manufacturer Sherco
Year 2011, 2012, 2013
Model 125
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