At about the time we were looking for someone to ride the XR for us, Bradley came aboard and made the perfect, er…guinea pig to ride the hog (we just had to work that in somehow). An initial shakedown at Buttonwillow Raceway was followed by a Pacific Track Time day at Infineon Raceway. Interestingly, because the track day was within 30 days of the AMA race there, we had to obtain permission from the AMA for Bradley to ride the bike at Infineon; a ruling disallows competitors to ride at a track within 30 days of an event, with certain exceptions made — one of which is for media. While the XR in standard trim is a solid platform and handles reasonably well, in race trim with the suspension significantly extended for ground clearance and the geometry accordingly changed, stability becomes a major issue. In our initial testing this was a limitation that suspension adjustments could mask to a certain extent but not cure.
The dyno run shown here for...
The dyno run shown here for the modified XR1200 is using the AMA’s spec fuel, Sunoco 260 GTX; the stock run was with premium unleaded.
That was not our only problem at the Infineon track day. The XR dropped a valve during the last on-track session, most likely due to over-exuberant downshifting on Bradley’s part. While rev limiters work fine during acceleration, there’s no stopping the engine spinning too fast if downshifts are made too early entering a corner. Luckily, we were able to drop the bike off at the Harley-Davidson fleet center to be repaired. Damage was limited to the top end on one cylinder, but a new piston, valves and cylinder head were still required. Lesson learned.
The Vance & Hines solid rear...
The Vance & Hines solid rear engine mounts replace the stock rubber pieces that tie the engine, frame and swingarm together, improving handling but also increasing vibration. You can see the new engine mount in place just behind the footpeg in the picture above.
The $175 Barnett clutch kit...
The $175 Barnett clutch kit for the XR1200 consists of tempered steel plates and carbon fiber friction plates with a segmented design to increase oil flow and extend clutch life. The company also offers a stiffer clutch spring, but the rules permit only the stock piece or an H-D replacement.
We used Maxima's Maxum4 Extra...
We used Maxima's Maxum4 Extra 15W-50 ($15.49 per liter) in both the primary case and crankcase of the SR. After every track day the bike got fresh crankcase oil and a new K&N filter (complete with wrench nut for easy removal and pre-drilled for safety wire), while the primary case was changed after every two days. Note that the oil filter is all-black, specifically for Harley applications.
Just before the AMA event at Infineon Raceway, Vance & Hines released a fix for the wobbly handling, in the form of solid rear engine mounts. The XR’s engine is completely rubber mounted to reduce vibration, but the rear mount also incorporates the swingarm pivot, making the frame/swingarm connection flexible enough that you can see movement with the bike even just idling at a standstill. With the solid nylon mounts installed, handling is significantly improved but vibration is increased as well. With the engine fixed and the engine mounts installed, we headed back to Buttonwillow for a TrackDaz track day to test everything and make any final adjustments. Handling was quite improved and we felt ready for the AMA race; there was just one last hitch in the form of a slipping clutch, which we remedied with a complete kit from Barnett. Testing completed, we headed off to Infineon Raceway for the AMA event. Tune in next issue for the results and full story.
Dunlop Sportmax D211 GP-A Spec Tires
As part of the AMA Pro Racing series, the Vance & Hines XR1200 class runs under the spec tire rules, meaning all bikes on the grid use the same Dunlop Sportmax D211 GP-A tires. With a 5.5-inch rear rim and the replacement Vance & Hines front wheel, the XR uses the same 120/70 front and 190/55 rear tires as the Daytona Sportbike and Supersport classes, which are available in three front and two rear compounds. The GP-As are manufactured in Dunlop’s Buffalo, NY plant, and use the company’s Jointless Band (JLB) and Multi-Tread construction; the rear tires are dual-compound, with a harder center portion for wear and a softer edge tread for grip. For the XR class specifically, the AMA and Dunlop select compounds for each track, meaning competitors all use even the same compound of tire. The spec tires are controlled through the use of stickers; competitors are given a set of stickers at the beginning of the weekend (four front and four rear in the XR class), and these must be applied to all tires used. Prior to each on-track session, AMA staff members check each bike to ensure the stickers are in place.
The Dunlops coped surprisingly well with the XR, considering its heft — the minimum weight for the XR class is 520 pounds compared with roughly 380 pounds for the other classes. Bradley reported good traction and neutral steering properties, and the tires showed good wear over the course of a track day, with only the rear showing signs of abuse at the end of a day. The Dunlop Sportmax D211 GP-A tires as used in the AMA cost $360 per set.