How Much Does Reboring an Engine Cost?

Written by: Staff

Reboring an engine will be commonly done when the piston, piston rings and the cylinder becomes damaged, either due to wear and tear or excessive usage.  When the cylinder’s wall becomes damaged, it can be rebored to a larger size and larger pistons will be used in its place, and after the reboring is done, the next step will be a process known as sleeving, which involves placing a sleeve inside the cylinder.  According to members on Quora, the only time a reboring job will be done is when the cylinder is barrel shaped.  This process can also be done if you’re looking to increase the power of the engine since reboring can increase the cylinder capacity.

DSC_3532_pp by WalterPro4755, on Flickr
DSC_3532_pp” (CC BY 2.0) by WalterPro4755

How much does reboring an engine cost?

On average, reboring a small boat or ATV engine can cost anywhere from $40 to $65 per cylinder, while a car can cost anywhere from $75 to $175 per cylinder depending on the make and model.

For example, a bare block job can be in the $250 to $500 range, while an assembled engine can range anywhere from $800 to as much as $1,500.

According to, reboring boat engines can cost $45 to $50 per cylinder.

On The Mini Forum, one member shared his itemized bill from his mechanic when he had this procedure done.  The total, even though it was in pounds, was close to $550.   This included reboring to the next size up, a new set of pistons and decking the block top surface to suit the new parts.  It also included a new set of bearings, re-grind, a timing chain, gaskets and fitting.

On, a member said he charged $125 to bore or $125 to plate hone.

Reboring an engine overview

To see if boring is necessary, a mechanic will perform a visual inspection and will measure the bore with his or her fingernails.  Usually, reboring will be necessary if honing can’t resolve the issue.  For instance, if the fingernail is able to grip a scratch, then it’s too deep and reboring will be required.  Also, if the cylinder is un-round or oval, or flat spots are noticed on the cylinder wall, then these are all things the mechanic will take into consideration when recommending a reboring procedure.

What are the extra costs?

Reboring isn’t always the answer.  Some mechanics may recommend replacing the pistons and cylinder kit with a new one.

How can I save money?

Consider talking with at least three to five different mechanics to see what they charge.  Each shop is going to have its own recommendation on what’s best for your engine.

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