Community Commentary Racing Past 60 | YZ450F Mechanical Failure at AFM, Round 1

Racing Past 60 | YZ450F Mechanical Failure at AFM, Round 1

Ultimate MotorCycling Amateur Race Report, #3

Racing Past 60 | YZ450F Mechanical Failure at AFM, Round 1
Marc Rittner with his YZ450F Supermoto

This was the first 2016 AFM race weekend of the year, and surprisingly I had my race bike fully prepped and ready on Thursday night.

My plan was to drive up to Buttonwillow Raceway Park, Buttonwillow, Calif., on Friday afternoon, unload my bike and gear into the rented trackside garage, do a little visiting in the paddock, have a good night’s sleep at the motel, and get to the track early on Saturday.

No practice for me on Friday, as I had already had everything tuned and ready from my track-day session earlier in the week with Let’s Ride Trackdays.

I saw many familiar faces as I cruised through the paddock. Of course there was Jason Paden and John Slobom of Race Tire Services with their large Dunlop presence. A quick hello to Dave Moss of Dave Moss Tuning; Moss is an internationally recognized suspension expert and accomplished racer who had helped me with some suspension tuning during 2015. Further down the paddock I found engine builder Gregg Spears of Spears Enterprises, and his sponsored rider Austin Guinn. Austin and I had battled at the 2015 AFM Round 7 season finale in the Formula III class (check out video here of our AFM battle), and we had a candid discussion regarding some of the finer details of our respective race bikes.

I headed for my garage and found that one of my race buddies had gotten there before me and already had his bike and gear situated. This was my first time seeing one of the track’s recently constructed all-new garages, and they were very nice. The garage was spacious with great lighting, lots of power outlets, and huge roll-up doors. The doors were wide and tall enough for me to just back-in my van and unload all my stuff. During the weekend we comfortably accommodated a total of five racers in two adjoining garages.

Six a.m. Saturday morning came soon enough, and I departed my luxurious Motel 6 suite for the 10-mile drive to the track. It always takes longer than you think to get ready at the track in the morning, so getting there early allowed me to complete my registration and get my bike and gear approved by Tech Inspection. Tasks completed, I pushed my bike back to the garage and put it up on stands with tire warmers.

My tires weren’t up to temperature when the third and final call went out for the first practice rotation, so I waited for the second rotation. Practice groups are by lap times, and my Group 3 was populated mostly with middleweight twins, ¾ 600’s, and a smattering of larger bikes that were not quite achieving their potential. All went well for me during the first few laps, and despite a fair amount of traffic I was easily able to maintain my desired pace and practiced setting up some passes. It looked like it was going to be a good day.

Apparently it takes no more than a fleeting positive thought to jinx it, because things went seriously wrong on the sixth lap. Accelerating out of the Turn 2 “Offramp” I heard a loud pop, and saw a metallic object flying away from me up the track at a high rate of speed. I puzzled over the situation, thinking it quite odd to be passed on the track by a piece of my own motorcycle. In that brief moment I speculated that perhaps it was the piston being freed from the bonds of its cylinder. Whatever the scenario, I knew that it couldn’t be good.

The engine locked-up, causing the rear wheel to skid and the bike to slew sideways toward the upcoming turn. I grabbed for the clutch lever and pulled it just in time to avoid being spit off in a high side crash. The bike snapped back into line, and I veered the off the racetrack into the dirt runoff area in order to avoid oiling down the track, as we are all instructed to do at every rider’s meeting. A track corner worker directed me to park it up against the perimeter fence, where I had my first chance to inspect the bike.

It turns out that the UFO I observed was a large piece of aluminum from the front of the engine cases. The gaping hole it left behind was presumably caused when my YZ450F’s connecting rod attempted to exit the cases with great prejudice, apparently indignant from the many days and many miles of screaming high rpm abuse that I had subjected it to. Not good.

The corner worker directed me to hustle back over the pit wall so that the next session could get on track. Note: Jogging in full leathers, race boots, and full-face helmet is not recommended. Later on during the lunch break the efficient AFM crew retrieved my bike and delivered it back to my garage for BDA (Battle Damage Assessment).

I grabbed a flashlight and shone it into my new “crankshaft inspection port”. To my , surprise I spotted an unattached piece of connecting rod just laying there inside, leaving no doubt as to the cause of the damage. I guess the good news is that my homemade fiberglass bellypan properly did its job in containing escaped fluid, leaving the track unfouled and racing uninterrupted. (photos)

Without a raceworthy bike, there was nothing left to do except load up the van and go watch the races. My race for that day (Formula III) ran at a good pace with some great passing. I missed being out there in the mix, but all I could do was study the action with an eye toward the next opportunity to do battle.

With only 4 weeks left before the April AHRMA vintage races at Willow Springs International Raceway there is no time to waste in getting started on my engine repairs. Last year I won back to back races in the AHRMA Sound of Singles 2 (450cc) class. This year I’m coming back to defend my turf.

Marc Rittner

AFM Expert #129

Riding Style

Next report: 2016 AFM Rounds 5-6, Buttonwillow Raceway Park

Read previous reports from Ultimate MotorCycling Amateur Race Report, Racing Past 60:

Racing Past 60 | Marc Rittner Intro

Racing Past 60 | Rittner Preps for 2016 AFM Race Season

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