Sherco Top End Engine Rebuild Kit - 290cc - 2000 to 2005

Part Number
RKTS99290
Grouped product items
Product Name Price Qty
Sherco 290 Piston Kit Size A
0 in stock - Available to order
£154.99
Sherco 290 Piston Kit Size B
0 in stock - Available to order
£154.99
Sherco 290 Piston Kit Size C
1 in stock
£154.99
Sherco 290 Piston Kit Size D
0 in stock - Available to order
£154.99
Sherco Cylinder Base Gasket - Narrow - 0.5mm
42 in stock
£7.32
Sherco Cylinder Base Gasket - Narrow - Shim 0.2mm
1 in stock
£3.24
Sherco Cylinder Base Gasket - Narrow - Shim 0.3mm
5 in stock
£3.24
Sherco Cylinder Base Gasket - Narrow - Shim 0.4mm
2 in stock
£3.48
Sherco Inner Cylinder Head O-Ring Large
96 in stock
£4.77
Sherco Outer Cylinder Head O-Ring Large
112 in stock
£4.98
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
Athena 18x22x22 Little End Bearing
9 in stock
£7.20
Aluminium Flat Seal Crush Washer - M5x9x1
261 in stock
£0.30
Top end rebuild kit including the piston, gaskets and O-rings

For the Sherco ST290 trials bikes from mid 2000 to mid 2005 (these earlier bikes came with the narrow Base gasket).

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

Piston Sizes

LetterSizePart number
A 75.95mm M245
B 75.96mm M589
C 75.97mm M590
D 75.98mm M591


The factory recommended piston to cylinder tolerance for the 290 is 0.027 to 0.037mm, 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.

These pistons usually come without the half moon shaped cutout on the bottom of the skirt on the inlet side, some Sherco's have the cut out some do not even straight from the factory, we find it makes no difference which piston you use.

18mm Gudgeon Pin by 52mm long
Centre of the gudgeon pin to the top edge of the piston 29.1mm
Overall height 68mm
Height from top to the edge of the piston 4.5mm
Weight including rings, gudgeon pin and C-clips 328 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.

We recommend you set your squish (the gap between the top edge of the piston and the cylinder head) to around 1.20mm.

More Information
Manufacturer Sherco
Year 1999, 2000, 2001, 2002, 2003, 2004, 2005
Model 290
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