46mm Pop Up Piston Kit Husqvarna 555 560 562XP MK1 505215502

Pop-up piston kit, 46mm, for Husqvarna 555, 560 and 562XP chainsaws. Replaces Husqvarna part number 505215502. Contents: piston with a raised crown, one piston ring, wrist pin and circlips. A pop-up piston has a domed crown that sits closer to the cylinder head at top dead centre. That tightens the squish band and raises compression, and that is where the extra power comes from. It is an aftermarket performance part - Husqvarna does not list a pop-up piston, and 505215502 is the standard factory number this piston replaces. Fits 555, 556, 560, 560XP, 560XPG, 562XP and 562XPG, and the Jonsered CS2258 and CS2260. All are 59.8cc on a 46mm bore, and the piston is common to all of them. This kit is scoped to the original Mark 1 saws. The 562XP Mark II is a separate model with its own parts catalogue and we have not confirmed that this piston carries over to it, so check your diagram before ordering for a Mark II. Because a pop-up changes squish clearance, measure it on assembly. Run a solder test through the spark plug hole and pick base gasket thickness from what you measure. If the squish is too tight the dome will contact the head. Piston kit only. Cylinder, needle bearing, gaskets and crank seals are not included.

• POP UP PISTON KIT, 46MM - Piston with a raised crown, one piston ring, wrist pin and circlips. The raised dome tightens squish clearance and lifts compression, which is where the extra power comes from. This is an aftermarket performance piston. Husqvarna does not catalogue a pop-up.
• REPLACES HUSQVARNA 505215502 - The factory number is nine digits, written 505 21 55-02. Fits 555, 556, 560, 560XP, 560XPG, 562XP and 562XPG, plus the Jonsered CS2258 and CS2260. All of those are 59.8cc on a 46mm bore.
• SCOPED TO THE MARK 1 SAWS - This kit is for the original 555, 560 and 562XP series. We have not verified fitment on the 562XP Mark II, so check your parts diagram before ordering for a Mark II rather than assuming it carries over.
• MEASURE YOUR SQUISH ON ASSEMBLY - A pop-up changes squish clearance, so check it with a solder test through the plug hole and choose base gasket thickness to suit. Too tight and the dome will touch the head. This is standard practice on any pop-up build and it is not optional.
• RICHEN IT AND RUN IT IN GENTLY - Raising compression raises combustion temperature, so a pop-up build wants a slightly richer high-speed setting and an easy first tank rather than full throttle out of the box. Check the plug color after that first tank. Cylinder, needle bearing, gaskets and crank seals are not included.