Power Kits

More power with power kits

Your engine is in pretty good shape, but you're still missing that oomph? A boost in displacement and compression would be very helpful.

It's a good thing that our Harley engines provide a number of options thanks to the design of the flywheel assembly. And it's also good that W&W has something to offer here: flywheels with more stroke and matching stroker pistons. Cylinder heads with smaller combustion chambers that increase compression. And, of course, the right pistons for enlarged cylinder bores.

What is a stroker? What is a stroker engine?

Stroke is the English word for the path that the pistons travels through the cylinder from bottom dead center to top dead center. A stroker is an engine that has more stroke than the standard engine. As is well known, all classic Harley-Davidson V engines are so-called long-strokers. The dimension for the stroke is larger than the dimension for the bore. Such engines have a reputation for developing more torque in the lower rev range. With the right set-up, a stroker will significantly increase this torque: exactly what is needed at the traffic lights and for 1/4 miles.

What is a big bore?

The word means a larger (cylinder) bore. However, the classic Harley-Davidson V engine remains a long-stroke engine, the dimension for the cylinder bore generally remains smaller than the dimension for the piston stroke, even after reboring.

Stroker or big bore? What do I need?

There's good power gain either way. From a technical point of view, it is relatively easy to lengthen the stroke of Harley-Davidson V engines by changing the flywheels of the crankshaft and the pistons. However, the entire engine has to be dismantled and the flywheels have to be balanced to the piston weight. Enlarging the bore means replacing the cylinder and piston; on Harley-Davidson V-engines, the bore in the engine housing usually has to be enlarged. Here too, the engine must be removed. So there is hardly any difference in terms of effort.

Any lengthening of the stroke yields more torque at lower engine speeds. On the other hand the longer stroke means higher piston speed. Enlarging the bore does not increase the torque so dramatically in the lower rpm range, but rather in the middle range. Ultimately, it depends on your personal riding style and preferences. And maybe a big-bore stroker is an option?