Even with a nearly $8000 budget,...
Even with a nearly $8000 budget, Shierts still chose to use the stock Suzuki crank and connecting rods on Big Shot-a true testament to the strength and durability of the Hayabusa's bottom end.
All engine builders have the same parts to choose from when building a race motor, so all race motors built with the same parts should offer the same performance, right? Not exactly, which is why it becomes key to hook up with an experienced builder like Shierts if you're looking for max power. Many builders are content to order the aftermarket parts and assemble according to the manufacturer's instructions and hope for the best. Aftermarket parts are just raw materials to someone like Shierts, though, who modifies and hand-preps every single part using all manner of little tricks and techniques picked up and proven over the years-many of which will never leave Shierts' head. This is where the "secrets" mentioned earlier come into play.
Shierts started by tearing the engine down completely and sending the cylinder block off to Millennium Technologies for boring and replating. We added 3mm to the 'Busa cylinders in order to bump the displacement to 1397cc, a common mod that Shierts has done to literally hundreds of Hayabusas over the years. While everything was apart, Shierts ported the head to his own specifications. This was one of the most expensive operations in the project at $1200, but Shierts says it's the key to releasing the hidden power that we were looking for. Once the port job was done, the head was reassembled with stock valves, but the valve springs were replaced with stronger pieces from Shierts' in-house stock ($160).
The best feature of the Nitrous...
The best feature of the Nitrous Oxide Systems (NOS) wet kit is the flexible nitrous feed lines, which make routing the system to the cylinders much easier than other kits that rely on hard lines. To avoid any clearance issues, we located both the fuel and nitrous solenoids behind the cylinder bank.
Since the bike would later get a NOS wet nitrous kit ($850 parts and $650 labor), the cylinder and head were machined to accept Shierts' own extra-strength studs. The stock studs are torqued from the factory to 36 ft-lbs, but Shierts' uprated studs allow the head to be torqued to 100 ft-lbs. This mod, along with the special high-strength head gasket ($70), ensures the head is not going to lift or move around when we hit it with the "Big Shot" of nitrous oxide that we had planned. This is an expensive operation eating up $670 of our budget for parts and labor, but if you want an engine that will hold up repeatedly to a 70-hp nitrous hit, this is the only route.
MTC Engineering hooked us...
MTC Engineering hooked us up with a set of their Pro-Lite pistons for this build. They also offer full-skirted models, but we selected some custom, semi-skirtless slugs to save some grams. Shierts hand-polishes each piston prior to assembly for optimum performance.
For pistons, we selected a set of custom-made MTC Pro-Lites, subtracting another $730 from the budget for these one-off slugs. Before assembly, Shierts hand polishes each piston to remove any tiny metal slivers that could cause pre-ignition, which would spell major meltdown for a nitrous bike. Each piston is also precisely weighed to ensure proper balance. Web cams with a custom grind specified by Shierts (the specs of which he prefers to keep to himself) were installed at this time, along with APE fully adjustable cam sprockets and APE's manual cam chain tensioner to keep the entire valve train moving as it should. Cam timing specifics are another "Ancient Shierts Secret."
The injectors for the nitrous...
The injectors for the nitrous oxide system are plumbed directly into the intake runners to insure the full shot makes its way to the combustion chamber. This location not only makes more power, it also reduces the chance of a nitrous backfire into the airbox.
When Shierts refused to share with us the final compression ratio, we had enough and demanded some hard data. We argued that when a customer drops almost $8K on an engine they should get all the specifics on that engine. "Just because you buy a can of Coca-Cola it doesn't entitle you to the recipe," Shierts retorted, and we had to concede his point. Suffice to say, listening to the bike start up and idle, this is not any high-strung, 14:1 time bomb that's going to grenade the first time you hit the nitrous button.
To help feed this beast, Shierts also installed a set of his own bored-out throttle bodies to increase airflow. These thinner bodies are reinforced with epoxy on the outer perimeter to make up for the inner material that was removed. The damage to the wallet was $400, but the result was a precious few more hp added to the rear wheel. The airbox was completely gutted (Shierts' "full airbox mod") and custom filters were epoxied inside to maximize airflow. The stock intake stacks were also removed and replaced with new higher-flow units. There goes another $145.