Cylinder Kit (Big Bore) 421cc ‘Assassin’ for Yamaha Banshee

These are our 68mm big bore standard port timing, stock appearing Assassin cylinders. These cylinders are a in house design from Driveline Performance which include 68mm Nikasil bore, triple exhaust ports, larger intake and transfer ports. We machine these cylinders in house on our CNC so we can ensure that all cylinder specs are proper for the +4mm long rod stroker crankshaft. Our cylinders are machined to specific heights so there are no spacer plates required a standard .020" base gasket is all that's needed.

The 421cc kit is designed to be used with a +4mm stroker crankshaft with 115mm rods.

The port specs on these cylinders are: 195 exhaust and 124 transfer durations. We only offer the 421cc kit in one port timing configuration now. After years of dyno testing on the 421 kits, we came to the conclusion that there was no substantial difference in horsepower or torque between the 421L.P and H.P. so we now just offer the one port timing.  

We have tested multiple exhaust manufacturers on our cylinders and most of them perform well, obviously the better the exhaust the more H.P. that will be achieved. Peak H.P. and power curves will also vary depending on the amount of compression and timing you choose to use along with the quality of reeds and carburettors that are being installed.

The dyno graph shows what H.P. can be achieved with the right components. That particular engine had pump gas domes (93octane), V-force reeds, 35mm Keihin carburettors, 6 degree's of timing and Shearer small bore inframes.

Horsepower numbers will vary depending on the pipes, carbs, reeds, etc,etc, that are being used. Please don't ask us what H.P. numbers are capable with your pipes, carbs as we have not tested every single part that's available for a Banshee. This graph is just to give an idea what is achievable.

Kit includes:

• 2 cylinders Nikasil plated to a 68mm bore size. We use Millenium Technologies for the Nickasil plating.
• 2 Wiseco forged 68mm Blaster style pistons with our custom intake window design, rings, wrist pins and circlips.
• 2 rubber water jacket plugs.
• 1 .020" base gasket.

Compatible with:
Yamaha Banshee