JS Motorsport Technical
Ultralight rods and pistons for Solid frames

The bushless ultralight rod below was designed for solid framed bikes such as the Atlas 750 and 500 to 650 Dominators. This rod is good for long stroke 750s up to 75 hp. Also works for short stroke 500 classic racers. They weigh 10 grams less on the small end than our regular bushless rod. Small end = 95 grams. Big end = 307 grams. This ultralight rod provides maximum smoothness for solid framed bikes. Crank rebalancing required. Requires DLC pins.

ultralight rod

68 to 69.5mm Hi C.R flat top pistons for 650 SS Dominator

The 68.5mm flat top piston below is refered to as 9:1 C.R. (closer to 8.5:1 C.R.) for 650SS Dominators. These pistons weigh approx 170 grams and go with our Ultralight 6.4″ length rods.

69mm flat

68 – 69.5mm domed pistons for 600 & 650ss Dominator

The 68 to 69.5mm centrally domed piston below is approx 10 C.R. for for 600 & 650SS Dominators. These pistons weigh approx 170 grams and go with our Ultralight 6.4″ length rods.

69mm dome

66 – 68mm domed pistons for 500 Dominator

The 66 to 67.5mm centrally domed piston below is approx 10 C.R. for a 500cc Dominator. These pistons weigh approx 170 grams and go with our Ultralight 6.4″ length rods.

67mm 170gm pistons

The bottom side of the dome is 3D undermilled to achieve minimum weight as in the photo below.

domed underside

High domed approx 11 C.R. 73.5mm piston below was designed for a 500 short stroke using a 750 motor destroked to 59.6mm. The higher dome is necessary to restore C.R. with the smaller displacement.

500 shortstroke

The piston below was designed with a smaller, centrally located dome for an exotic Norton 750 short stroke racer with a welded and re-machined bathtub shaped combustion chamber.

center dome

It is assumed that every race engine builder will check squish band, and valve pocket clearances.

Ultra lightened piston option

The skirts can be drilled and pins taper bored on special request as below for all size solid framed bikes and high RPM racers.

lightened piston