Cylinder Boring

With our dedicated fixtures and precision tooling, there is no better place to have your Triumph cylinder reconditioned.

 Doing our own machining allows us to control the outcome, and we have prepared many cylinders for street, show, and race winning engines using the same high quality methods.
Kwik Way FWS boring bar

 Cylinder boring... how it's done

All cylinders are bored from the base of the cylinder to insure it is square and parallel to the crankshaft centerline. After considering the piston material, climate, and application, it is bored to .003" of the desired final size. We also are equipped to cut a new chamfer in each cylinder for easy and safe installation of the rings. At this point the cylinder is straight, round, square to the base, and twin cylinders are parallel, but it still needs to be honed to size.

Boring Triumph cylinder on Kwik Way boring bar

Honing...using precision abrasives

The honing process removes any surface imperfections or tears in the metal left by the boring bar, determines finished bore size and cross hatch pattern. This is done with abrasive stones, with varied pressure and special lubricants, to create the perfect finish for your new piston rings.

Triumph Cylinder honing on Sunnen

Clean, clean, clean...

The bore is then scrubbed with detergent to remove all residual honing oil and material, and the cylinder is cleaned in a high pressure aqueous parts washer at 180º F, and is now meticulously clean.

After cooling, the rings can then be squared in the bore and checked for end gap, or packed for pick up or shipping. We can also install new cast iron or bronze tappet blocks or paint your cylinder with high temperature enamel for an additional cost.

Triumph preunit 650 cylinder boring

Your cylinder is then returned to you clean in an airtight bag, with new pistons, and rings gapped and ready to install.

You can install your pistons and cylinder with confidence, knowing that it is the best it can be.

Triumph 650 Cylinder with pistons

Cylinder sleeving

 "Sleeving" involves boring a cylinder, and pressing in a cylinder liner with a precision interference fit. The liner is then bored and finished honed. When done correctly, it is as good or better than the original.

In some cases a new cylinder is more cost effective, but for special or racing applications we may be able to help. We have sleeved Triumph cylinders with custom made ductile iron liners, which have a higher tensile strength and are far more durable than cast iron. Although sleeving cylinders is more labor intensive, a lot of rare and broken parts have been saved through this process.

For custom cylinder sleeves please contact the shop.

Triumph Chantland 750 Big Bore cylinderChantland Triumph Ductile Iron Sleeves


Boring hundreds of Triumph twin cylinders has given us the experience that other shops may not have.

Pre unit cylinder boring

Although we occasionally do vintage Harley, BSA, Norton, and other motorcycle cylinders our main focus is British four stroke engines.

Harley vintage cylinder boring
Please see our tech section for helpful tech sheets on piston and ring installation.
As of July 2022 our pricing is as follows:
Twin Cylinder reconditioning                                 $247.02 plus parts
Twin cylinder reconditioning with paint                $385.02 plus parts
Single cylinder reconditioning                             $136.62 plus parts
Triple Cylinder reconditioning                               $343.62 plus parts
Vapor Honing, Media blasting                                           Inquire
Twin Cylinder sleeving                                          $385.02 plus parts
Twin Cylinder sleeving  w/flange                          $412.62 plus parts
Single Cylinder sleeving                                       $247.02 plus parts
Two stroke Cylinder reconditioning                                   Inquire
Strip and paint cylinder with 500º enamel                            $138