Things are coming to a head with our XR1200 project bike, with lots to report since the last installment. Twisted Throttle has supplied us with a complete crash-protection kit from R&G Racing
for the Harley, including frame sliders, axle sliders, and a pair of nifty "cotton-reel" swingarm spools. Because the XR's swingarm has no provisions for mounting standard spools for a paddock stand, some ingenuity is needed if you prefer not to use a stand that the swingarm simply rests on. The R&G spools use the lower shock mount and wrap under the swingarm, with spools in the perfect spot for a stand. We also installed the company's rear axle sliders; the front axle sliders require a small modification (a short section of the axle must be drilled out) to mount, so we saved those and the frame sliders for another day as we were running out of time.
R&G Racing cotton-reel swingarm...
R&G Racing cotton-reel swingarm spools fit nicely and allow the use of a spool-type paddock stand
The XR1200 has a long-turn throttle tube, and we contacted G2 Ergonomics for a quick-turn unit
. G2 is one of the few (and maybe the only) companies that make such a product for the Harley's one-inch handlebar, and we used G2's quick-turn throttle on our KTM Super Duke project bike
a couple of years ago with good results. The tube for the XR has stayed in the spares bin for now; data from the track shows that Bradley is managing with the stock throttle tube for now, but we certainly plan to try the G2 unit at some point.
Following our track day at Buttonwillow Raceway, it was time to change the XR's oil and filter. In both the primary case and crankcase we used Maxima Racing's Maxum4 Extra full-synthetic four-stroke oil in 15W50 viscosity. Our contact at Harley-Davidson, Paul James, also races an XR in the AMA Vance & Hines series, and recommended a fully synthetic oil for both sides of the XR's engine, and that we overfill the primary case slightly to better cover and cool the clutch. K&N's XR1200 oil filter features the company's removal nut welded to the top and pre-drilled for safety wire, easing things considerably at each oil change.
Maxima's Maxum4 Extra full-synthetic...
Maxima's Maxum4 Extra full-synthetic oil. Photo courtesy of Maxima USA
G2 Ergo's quick-turn throttle....
G2 Ergo's quick-turn throttle. Photo courtesy of G2 Ergonomics
K&N oil filter with removal...
K&N oil filter with removal nut pre-drilled for safety wire. Photo courtesy of K&N
Bradley's dad Curtis changing...
Bradley's dad Curtis changing shock springs at the track
As mentioned in the last installment, we had to get permission from the AMA to attend the Pacific Track Time day at Infineon, as it was within the 30-day no-practice time limit for AMA racers. Prior to the track day, we lowered the fork oil slightly and installed a siffer set of rear shock springs, all as per the recommendations of Fast Bike Industries' Dave Behrend
. The XR handled a step better at Infineon, and in that department we found even more changed that will need to be done for the next outing. It's worth noting here that the standard XR handles well and has none of the instability of the racebikes; because such drastic changes in ride height are made to add ground clearance and quicken steering, the bike's geometry ends up being very aggressive, leading to the wobble. Adding to the problem is the XR's rubber-mounted engine, and just as we went to Infineon the AMA and Vance & Hines released an approved set of solid rear engine mounts that (our sources tell us) go a long way to curing the instability. We have a set of the mounts and will definitely have them installed before the next outing.
Check out this onboard video from the track, showing Bradley on the XR on a quick lap near the end of the day. Many thanks to the AMA for allowing us to attend and Pacific Track Time for accommodating us.
2011 Harley-Davidson Sportster XR1200X Video Review
Unfortunately, during the last session of the day the XR stopped running. A quick check of the bike's diagnostics showed some errors, and we dropped the bike off at the Harley-Davidson fleet center for a check. It turns out the XR had dropped a valve, most likely due to some over-enthusiastic downshifting by Bradley. While the XR - like practically every other bike - has a rev limiter, it can't stop the engine from over-revving during downshifts; in our case it was enough for a keeper to slip out of the valve collar, letting the valve drop into the cylinder. Fortunately, damage is minimal and the bike will be fixed well in time for the race at Infineon.
While the engine is being fixed, the shocks have been sent to Fast Bike Industries for some internal modifications, including stiffer compression and rebound valving and lengthening to raise the rear end of the bike even more. Also planned before the next outing is a trip to the dyno, to see how the bike runs with the Sunoco spec fuel and make any changes necessary to the fuel injection.
The AMA Pro Road Racing series makes its way to Infineon Raceway on May 13-15. The Vance & Hines XR1200 class has qualifying on Saturday the 14th, with the race on Sunday the 15th. Check out the AMA's Infineon Raceway event page for more information, including how to get tickets. Note that Bradley's name is on the entry list for the XR1200 class!