Sherco Top End Engine Rebuild Kit - 250cc - 2011>2022
Top end rebuild kit including the piston, gaskets and O-rings.
For the Sherco ST250 trials bikes from 2011 to 2022.
Also fits the Scorpa Twenty 250 models from 2014 to 2022.
Please select the piston and base gasket size required to suit your bike, each bike is different.
Both the small head bolt O-rings and Copper sealing are in this kit most bikes only need one or the other, I think all the bike with the single peice cast head use the O-rings and the bikes with the insert style heads (usually anodised in Blue or Orange) need the copper washers. This insert style head also has an additional O-ring to prevent leaks around the spark plug, agin this is included so please remove if you don't require it.
Piston Sizes
| Letter | Size | Part number |
|---|---|---|
| A | 72.75mm | M009 |
| B | 72.76mm | M586 |
| C | 72.77mm | M587 |
| D | 72.78mm | M588 |
The factory recommended piston to cylinder tolerance for the 250 is 0.024 to 0.035mm, 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.
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 1.10mm.
| Manufacturer | Sherco |
|---|
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Sherco Bottom End Engine Rebuild Kit - 250, 290 & 300cc - 2011>2022Starting at £1.99