Complete Engine Rebuild Kit - KTM SX50 '06-'08

A single-box engine rebuild package for the KTM 50 SX (2006-2008) and KTM 50 SX Pro Senior (2004-2005), bundling the bottom-end and top-end components needed for a full professional refresh under one part number (WR00003).

It is aimed at parents, club racers and workshops rebuilding a well-used junior motocrosser, where chasing individual crank, piston, gasket and bearing part numbers across multiple suppliers costs both time and money. Kits are built from Vertex, Hot Rods and Hot Cams components manufactured in the USA, with the exact parts in each kit matched to the engine it is designed for.

Wrench Rabbit rebuild kits have been rebranded to Vertex. The components are unchanged, so the box you receive may differ in appearance from the one pictured.

• Complete top-to-bottom engine rebuild supplied under one part number (WR00003)
• Application-specific fitment for KTM 50 SX 2006-2008 and KTM 50 SX Pro Senior 2004-2005
• Built from Vertex, Hot Rods and Hot Cams components
• Vertex piston and gasket components
• Hot Rods crankshaft and bearing components
• Components manufactured in the USA
• Costs less than buying each component individually
• Removes the need to cross-reference and source separate part numbers
• Exact contents vary by application — this kit is specified for the listed models
• Now supplied in Vertex packaging; components unchanged from the Wrench Rabbit kit

• Crankshaft
• Piston kit
• Complete engine gasket kit
• Oil seal kit
• Main bearing and seal kit

Check the kit against your bike's model year and engine number before starting work — this kit is specified for KTM 50 SX 2006-2008 and 50 SX Pro Senior 2004-2005 only.
Lay out and check off every component against the parts list before you strip the engine, so you are not stopped mid-rebuild.
Follow the KTM workshop manual for the correct disassembly sequence, torque figures and assembly clearances; do not rely on generic values.
Degrease and thoroughly clean the cases, cylinder and all reused hardware before assembly — any grit or old gasket residue left behind will shorten the life of new bearings and seals.
Pre-oil the crank bearings, big-end and piston skirt with fresh two-stroke oil during assembly, and fit the piston with the ring locating pin and arrow oriented per the manual.
Treat gaskets, seals and circlips as single-use items; never refit ones that have been removed.
Pressure-test or at least visually confirm the crank seals before firing up, as an air leak past a new seal will lean the engine out.
Run a proper break-in: several short heat cycles with full cool-downs between them, light load, and no sustained full throttle until the rings have bedded.
Use the fuel/oil premix ratio and coolant specified by KTM, and change the gearbox oil shortly after break-in to flush out assembly debris.
Store the kit sealed in its packaging in a dry place until the rebuild; keep bearings in their wrappers so they stay free of moisture and dust.