Cylinder Boring Services

PROFESSIONAL CYLINDER BORING AND HONING

Cylinder boring is the process of machining a worn, damaged or undersized cylinder bore to the correct diameter for a replacement or oversized piston. The finished cylinder must be round, straight and accurately sized to provide the proper piston-to-cylinder wall clearance.

Incorrect piston clearance, cylinder taper or out-of-round conditions can cause excessive piston noise, excess heat, poor ring sealing, reduced performance, accelerated wear and potentially serious engine damage.

Ken OConnor Racing has provided professional motorcycle, dirt bike and ATV cylinder boring services for decades. Every cylinder is carefully measured before machining. The finished bore diameter is established using the actual piston measurements, the piston manufacturer’s recommended clearance and the specific requirements of the engine.

After precision boring, the cylinder is plateau honed to achieve the required final diameter and an appropriate surface finish for proper piston ring seating and oil retention. Cylinder temperatures are monitored and controlled during the honing process. On two-stroke cylinders, the port edges are carefully chamfered to help protect the piston rings during operation.

Our goal is to provide accurate cylinder geometry, proper piston fitment and dependable performance for both stock and high-performance engines.

WHY PROPER PISTON-TO-WALL CLEARANCE MATTERS

Correct piston-to-cylinder wall clearance is critical to engine reliability and performance. Excessive clearance can result in piston slap, poor ring sealing, loss of compression and accelerated wear. Insufficient clearance can cause excessive friction, piston scuffing, ring damage and seizure as the engine reaches operating temperature.

At Ken OConnor Racing, piston clearance is established using the actual piston being installed, rather than relying solely on the nominal piston size stamped on the piston crown or printed on its packaging.

Different piston manufacturers, materials and designs may require different clearances. Forged and cast pistons can have different expansion characteristics, and the correct measurement location on the piston varies by manufacturer.

We measure each piston at the manufacturer’s specified gauge point and machine the cylinder to achieve the appropriate finished bore diameter.

Precision cylinder boring services require more than simply cutting a hole to a specified size. Proper measurement, accurate machining and correct final honing are essential to producing a dependable engine.

CYLINDER BORING VS. CYLINDER SLEEVING AND PLATING

Not every worn or damaged motorcycle cylinder can be repaired by boring it to the next oversize.

Cast-iron cylinder bores can often be machined for an oversized piston, provided sufficient material remains and the cylinder is structurally sound. However, cylinders with excessive damage, deep scoring or insufficient remaining wall thickness may require a replacement sleeve.

Many modern motorcycles and dirt bikes use aluminum cylinders with plated bores. These cylinders generally require specialized replating rather than conventional oversize boring and honing.

Ken OConnor Racing offers cylinder boring, cylinder sleeve installation and cylinder plating services for a wide range of motorcycle, ATV and performance engine applications.

Choosing the correct repair method helps preserve cylinder integrity, maintain proper piston fitment and extend engine life.

Cylinder Boring Price