Classic Motorcycle Build

1965 Sportster Project

Text and Pictures by Mark Trotta

When new, the 1965 Sportster XLCH was the fastest production motorcycle on the planet. It was a flat out, built for speed, no-frills hot rod, not much more than two wheels, a seat and a 900cc engine.

1965 Sportster Project

1965 Sportster Production: 2,815 XLCH models, 955 XLH models (3,770 total units)

I received this engine completely disassembled. The first thing I did was take all the parts out of the many boxes and spread them out on my workbench. Surprisingly, nearly everything was there, including nuts, bolts and hardware.

disassembled Sportster motor

Right-Side Case Damage

1965 Ironhead Sportster Project

The right-side engine case had a circular crack where the generator mounted, presumably from the bolts being over-tightened.

1965 Sportster project

The generator hole repair was very time-consuming, but necessary to keep the numbers-matching cases.

Left-Side Case Damage

Repair Cracked Cases

Internally, the left-side case was OK, but there was a 2" chip missing where the primary cover bolts up. Both engine case repairs were TIG welded.

Repair Cracked Cases

Read: Repair Cracked Cases

Original Factory Finish On Engine

For an authentic and correct motorcycle restoration, the factory finish should be left on engine cases. Most are quite hard to duplicate, so sanding down original cases is not a good idea.

1965 Sportster motor

Unfortunately, these cases had been painted black somewhere in the past. So without really having any other choices, I sanded off the black paint after the cases were repaired. This was very tedious and time consuming, because Ironhead engine cases have plenty of nooks and crannies.

Crank And Flywheel Build

After rebuilding the flywheel assembly I trued it on my homemade stand. This was another time-consuming part of the engine rebuild.

truing sportster flywheels

Read: Ironhead Special Tools

I also used my DIY truing stand to check straightness on the pinion shaft and sprocket shaft.

Sprocket Shaft run-out

The lower end rebuild was finally complete.

1965 Sportster Project

Engine Clearances Before and After

Mock-building the motor was necessary for several reasons. First, motorcycle engine clearances should be measured before disassembly. But when you start with a completely disassembled motor, you don't have that opportunity. This required the additional steps of assembling the engine to get the "before" measurements, then disassembling, repairing/replacing, and re-assembling.

Restoring Aluminum Engine Parts

The pitting and corrosion seen on these old parts is typical for a 50 year-old unrestored motorcycle. I sent the cam cover, primary cover, and rocker boxes out to have the old chrome removed.

polishing aluminum motorcycle valve covers

Six weeks later, when the parts returned, I began sanding and polishing them.

Read: How To Polish Aluminum Motorcycle Parts

Ironhead Sportster rocker box

Read: Ironhead Rocker Box Assembly

Broken Valve Spring

One of the old valve springs (don't know off which valve) had cracked in two pieces. Since I had no prior history of the engine, I could only speculate why. The most likely cause would be over-revving.

broken valve spring from Sportster motor

Cylinder Heads

Both cylinder heads were rebuilt, which included new valves, guides, and springs, and a three-angle valve job. All four rocker arms were replaced.

Read: Motorcycle Valve Job

rebuild motorcycle cylinder heads

Cams And Cam Cover Issues

Another reason for mock-building the motor was to check all parts were in proper working order. The cam cover did not go on and off easily like it should, indicating a cam mis-alignment was likely. This led me to find one of the cams was binding. After testing each cam individually with the other cams, I found out which one it was, and replaced it.

1965 Ironhead Sportster Project

Read: Install Sportster Cams

Ironhead Sportster cam set

Replace Cam Bushings

The cam cover bushings were replaced due to contamination from the acid after de-chroming.

cam cover bushing install

Read: Remove/Install Sportster Cam Bushings

Ironhead Transmission

Like the rest of the motor, the transmission was completely disassembled when I got it. Fortunately, I had a complete transmission from another Sportster, which I used as a reference to put this one back together.

Ironhead transmission build

Rebuilding an Ironhead transmission is a project within a project. It took a while, but the results were good. Clearances are in tolerance and it shifts fine.

Read: Ironhead Transmission Basics


Misc Notes

Financially, it would have been more profitable to part out a basket case motorcycle like this, but this was a very low production-year Sportster with matching case numbers.

classic motorcycle build

Read: 900cc Ironhead Engine Build