46mm Pop Up Piston Kit 1127-030-2003 Fits Stihl 029 MS290

Raised-crown 46mm pop-up piston kit, with rings, wrist pin and circlips, that fits the Stihl 029 Super and MS290 chainsaws, the 56.5cc saws on the 46mm bore. Replaces piston 1127-030-2003. Some early plain 029 saws are 45mm, and the MS310 (47mm) and the 039 and MS390 (49mm) take different pistons, so measure your old piston before ordering. The crown projects further into the combustion chamber than the flat-topped factory piston, raising compression for more low-down torque and easier starting. Measure squish clearance with solder before running it, do not delete the base gasket as well, and find the cause of the old failure first.

• 46MM POP-UP PISTON KIT - Piston, rings, wrist pin and circlips. Replaces piston 1127-030-2003.
• FITS STIHL 029 SUPER AND MS290 - The 56.5cc saws on the 46mm bore. Some early plain 029 saws are 45mm, so measure your old piston before ordering. The MS310 (47mm) and the 039 and MS390 (49mm) take different pistons.
• WHAT A POP-UP DOES - The crown projects further into the combustion chamber at top dead center, which raises compression. The factory piston is flat topped. Expect more low-down torque and easier starting, not a guaranteed power gain.
• MEASURE SQUISH BEFORE YOU RUN IT - A raised crown uses up squish clearance. Check it with solder through the plug hole, turning the engine through top dead center by hand, and do not delete the base gasket as well: the two changes stack and the crown can reach the head.
• FIND OUT WHY THE OLD ONE FAILED - A scored piston had a cause. A hardened crankshaft seal, a split intake boot or impulse line leans the mixture and will take the new piston the same way. Pressure and vacuum test the crankcase, set the high speed slightly rich and run the first tank gently.