The lightweight AC generator...
The lightweight AC generator kit (left in both images) includes a heavy-duty cover and replaces the heavy outer-rotor design of the stock unit (right in both images) with an inner-rotor setup. The setup saves weight as well as drag on the motor but requires the engine to be spinning at high rpm to charge the battery.
This alternate gear cluster...
This alternate gear cluster has a higher ratio than the stock transmission, closing up the gearbox. The kit shift star seemed to make our bike shift more easily than our current test unit, but that may be just our two particular bikes rather than a difference of design.
Machined aluminum intake stacks...
Machined aluminum intake stacks are made of unequal lengths and replace the stock plastic parts of all one height, smoothing the power curve. The kit ECU has individual mapping for each cylinder to account for the offset. The stacks are shown here installed along with the BMC air filter supplied with the kit. After a tipover at dusty Buttonwillow, we replaced the filter with a K&N unit ($79). We also used K&N oil filters, which have a drilled nut welded on, making installation, removal and safety wiring a breeze.
Right after the track day our Triumph rep sent replacement valve springs to be installed before we rode the bike again, notifying us that the dealer teams had trouble in that area at Daytona. This gave us an opportunity to have the engine massaged for some more steam, though, and after talking with other builders more familiar with the Daytona we decided to have the head skimmed while it was off. Andrew had asked to perform this modification during the original build, citing plenty of clearance and more power, but-wanting to keep to the kit instructions as much as possible and looking for the most reliability-we declined. We realized after the track day that more steam would be required to run with the big boys, so 0.020 inch came off the head, boosting compression but keeping clearances well safe according to the manual.
The Arrow exhaust available...
The Arrow exhaust available from Triumph weighs less than 10 pounds. The stock unit, including the lights and license-plate holder hanging off the silencer, scaled in at 27 pounds.
The manual called for some...
The manual called for some machining of the exhaust port to match the Arrow exhaust pipe's spigots. Quite a lot of material needed to be removed.
The STM slipper clutch is...
The STM slipper clutch is a work of art and a necessary addition to the Triumph engine for racing.
With the engine returned and installed in the frame, local WERA and occasional AMA racer Chad Lewin was conned-er, enlisted to ride the bike at a Buttonwillow club race and then the Infineon Raceway round of the AMA series. Tune in next issue for the full details of our exploits.
After the original build didn't...
After the original build didn't result in the horsepower numbers we were hoping for, Andrew had the head ground to increase compression while the engine was apart to change the valve springs. Because the squish band is level with the head's surface, shaving the head doesn't affect squish clearance. We needed some rocket fuel to deal with the high compression, and VP set us up with U4.2 for WERA races, but the oxygenated fuel is not legal for AMA. For Infineon we used the tricker (and more expensive!) AMA-legal MRX01. The U4.2 costs $70 for a five-gallon pail, while the MRX01 costs $115.
Wild Hair Accessories imports...
Wild Hair Accessories imports these unique frame sliders ($165) from GSG-Moto. An aluminum plate attaches to the engine mounts, while the nylon protector mounts to the plate-no cutting of the bodywork is required. The company also offers axle protectors, but we were changing wheels so often-requiring the protectors to be removed each time-that we left them off. A crash at Buttonwillow bent the right-side frame slider plate dangerously close to the cylinder head, and the stress on the plate eventually led it to crack and break. Note the carbon-fiber engine covers, part of the Triumph kit, that attach to the stock covers with two-sided tape. The AMA's tech inspector at Infineon Raceway was reluctant to pass them, as they are not strictly engine covers but more an appearance piece. We used Motul's 300V 5W-40 double-ester synthetic oil in the engine, changing the oil and filter every two days of riding.
With the kit parts installed...
With the kit parts installed and before the cylinder head was shaved, we saw a healthy increase in peak power along with more overrev. This run is with VP's U4.2 fuel and is shown against the curve for our stock '08 test bike. As impressive as it is, 119 horsepower isn't enough to compete with the full-on FX bikes; other Triumph teams are reporting as much as 130 horsepower from their engines. We dropped our engine off at Hypercycle with a request for Carry Andrew to "work some magic," and he delivered: The rebuilt motor was much stronger. Unfortunately we didn't have a chance to get it on our dyno-we'll explain why in part II of the story.