First outing: Autobahn
Well past sundown on the Friday night of Labor Day weekend, we arrived at Autobahn Country Club, in Joliet, Illinois, with an almost complete 1988 GSXR750. Before it could be ridden, we still needed to install a new sprocket carrier bearing, replace the oil-soaked old brake pads with fresh SBS race-spec items and have Superbike Kenny from SB Suspension look over the machine's forks and shock. Fortunately, this Sportbike Track Time event at Autobahn was a three day affair, so we'd have plenty of time to solve all these problems and do some testing.
As recounted in the first article of this series, AHRMAgeddon It, we'd acquired a beat up, barn find, ex-racebike Gixxer in unknown condition. During the first seven days of the project, we had invested an honest hundred hours of midnight oil into the machine, while still staggering through a forty hour week at the day job. Our goal was to enter the June AHRMA event at Road America, in Elkhart Lake, Wisconsin, which at this point left us just two more weeks until the green flag dropped. Thus far, we'd succeeded in getting the engine started and had run the transmission through its gears on a rear stand, as well as replaced all the fluids, thoroughly cleaned the machine and repaired all the damage we'd found. We'd also swapped in a wider rear rim and a BMW S1000RR shock. Our goal for this first track weekend was to get in some laps and figure out what else was needed to get it race ready.
At dawn, we yanked the bike's rear wheel and installed a new sealed bearing in the sprocket carrier. At this point, we decided to risk taking our first ride on the bike. Even idling around the paddock at just above a walking pace it was clear that the front suspension was seriously messed up. We proceeded carefully over to the SB Suspension truck. Tuner Ken Hall bounced on the bike a few times, grimaced, gave us his patented, "You're kidding, right?" look, then told us to go yank the forks and shock off the bike and bring them back to him.
When Superbike Kenny shows up at a racetrack, his time is in great demand. A steady stream of riders arrived at his pit throughout the day, looking for suspension setup work and other repairs. Since he was wrenching on our decrepit old junk in the free moments between those other jobs, it took most of the day. Late that afternoon, we reinstalled the modified suspension. Ken had converted the BMW shock's spring perches to accept an aftermarket spring and then replaced the OEM coil with a stiffer one which would better suit our application. As for the Gixxer's front end, it appeared that before the machine's racer owner had sold it off as a street bike, its racing fork springs had been removed. In their place was crammed a pair of coils which were far too long for the application. What we'd been feeling while tiptoeing around the paddock was the forks moving through perhaps an inch of travel before going solid over every little bump due to coil bind. No wonder the bike bore evidence of several street crashes!
By now Saturday was nearly over but the bike was coming together. Chris Jenson had arrived with the SBS Dual Carbon brake pads and we'd installed them while waiting for Superbike Kenny to finish. The tires went on warmers as soon as we got the forks and shock back. We reinstalled the suspension, slipped the wheels into place, leathered up and swung into the saddle. Talk about nervous! So much effort had gone into this machine. So many problems had been addressed, yet the bike was still a huge unknown. Here we were, heading out into late afternoon trackday traffic on a bike that we weren't 100% sure was going to work. It was the moment of truth.
The first lap was an eye opener. The bike stopped and turned far better than we'd expected. Modern Michelin slicks and the latest Dual Carbon SBS brake pads worked exactly as they would on a modern motorcycle. Ken Hall had done an excellent job of making the suspension functional, so it wasn't delivering any nasty surprises. As we picked up the pace, the two glaring issues were carburetion and ground clearance. The engine did not want to pull cleanly off-corner and while leaned over, the rider's toes were touching down before his knees. In spite of this, we'd begun passing other riders. A lot of other riders. By the fifth or sixth lap, it was clear that we were having WAY too much fun on a bike which we were presumablyjust shaking down. Regretfully, we headed for the pits.
On Saturday evening, a thorough scan of the machine was performed. Incredibly, nothing was dripping, rubbing or loose. This rebuild had been a sleepless seven-day marathon and we just couldn't believe how well the machine had performed in its initial session. The machine worked, right out of the box. In fact, it seemed more modern than vintage! Still, there were issues. Our new goal was to make it work better. Little did we know, this would become the defining mission of the entire rest of our season.
We took the bike out a number of times on Sunday and Monday, with lots of work in between. Trying to get the bike to pull cleanly under partial throttle was proving quite difficult. No matter how smoothly we rolled on the gas, the bike would stumble it's way to about ten thousand RPM and then go like hell to the redline. Eddie Bingham, of Naperville Motorsports, was instrumental here in moving us forward. He synchronized the carbs, then talked us through a series of needle position and main jet changes; however, none of this fully solved the problem. In fact, it was beginning to seem as if the bike was possessed. It would leave the pits running reasonably well. The hotter it got, the worse it ran. Sometimes, the bike seemed not to be running on all cylinders, yet when we'd check them, the plugs would all fire. Then the bike would seemingly run out of fuel, yet would have gas in the carbs when we opened the bowl drains. It would always stumble when leaving corners but was strong on the main jets, except when it wasn't. This was the most baffling set of symptoms we've ever fought. We left Autobahn knowing that we had a motorcycle with great potential. Realizing that potential was going to require a lot more effort.