Classic Motorcycle Build

Ironhead Top End Rebuild

Text and Pictures by Mark Trotta

Compared to the bottom end, rebuilding the top end of an Ironhead Sportster requires less time and less special tools.

Ironhead top end rebuild

The two main obstacles will be if the cylinder jugs need boring, and if the valve seats need to be re-faced. If you're lucky, you may get away with just honing the cylinders, re-using the old pistons, and installing new piston rings.

DIY Rebuild Ironhead Top End

Aside from basic hand tools, you'll need a few engine rebuilding tools such as a piston ring installer, torque wrench, dial caliper, and feeler gauge. There are also a few specialty tools needed, although some of them can be fabricated.

Cylinder Boring And Honing

New cylinders, whether they are new or aftermarket, need to be accurately measured, bored, and honed. A good straight bore with a proper cross-hatch pattern, and correct piston to wall clearances, is a MUST for good sealing and ring life.

Motorcycle cylinder hone

Read: DIY Motorcycle Cylinder Boring

Read: DIY Motorcycle Cylinder Honing


Ironhead Rebuild Kit

An alternative to measuring and boring your old cylinder jugs is to buy aftermarket ones. Rebuild Kits for 1973 through 1985 Ironhead Sportsters are still available.

Ironhead Sportster rebuild kit

Shop: Ironhead Cylinder And Piston Kit

The only physical difference between aftermarket Ironhead cylinders and factory cylinders is that they do not have casting numbers on them. Instead, they are marked "F" and "R".


Top End Gasket Kit

James Gaskets are simply the best gaskets available for your Ironhead. Their top-end gasket kit replaces H-D 17030-72 and includes everything you need to re-seal your top end.

james gasket top end gasket kit for harley sportster 1973 1985

Shop: Ironhead Top End Gasket Set 1973-1985

This top end gasket set includes copper head-gaskets, oil seals, O-rings, and all other gaskets necessary to completely rebuild an 1973 through 1985 Ironhead top end. James Gaskets are proudly made in USA.


An alternative to the factory rocker feed lines is adding chrome plated stainless steel lines.

top end rebuild harley sportster 1973 1985

Shop: Ironhead Rocker Lines

The lines are pre-cut and fit all 1957 through 1985 Ironhead Sportster motors.


Cylinder Heads

Ironhead Sportsters are named after their cylinder heads. Since they're made from cast-iron, they're durable and rebuildable up to a point. The biggest problem often caused by the ham-fisted mechanic who tried fixing it before you.

900cc Ironhead Sportster build

Read: Motorcycle Valve Job

rebuild motorcycle cylinder heads

Read: What Is A Three-Angle Valve Job ?

how to remove valve guides from cylinder head

Read: How To Remove Valve Guides

Ironhead engine rebuild and repair

Read: How To Install Valve Guides

Ironhead Sportster rocker box assembly

Read: Ironhead Rocker Box Assembly

Ironhead rocker box assembly

Read: How To Polish Aluminum Motorcycle Parts


Related Articles:

Ironhead Engine Build
Ironhead Sportster Cylinders
Ironhead Rocker Box Assembly
Remove/Install Sportster Cam Bushings
Install Sportster Cams
How To Adjust Ironhead Valves
Motion Pro pushrod tube tool 08-0255

Read: Ironhead Special Tools