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Monday, February 16, 2009

The Ice Quiver, part 2

This is my son Scott's bike, a '95 YZ125 that we got as a DTX when he was overdue for a move up from his XR100, way back in '00 I think. This bike has seen quite a bit in the past 8-9 years, it had been lowered and set up as a DTX (dirttrack bike from a stock motocross frame) with 19" front spool wheel. Then we built a pair of 17" supermoto wheels and raced it at Lembo Lake and Cuddebackville. Then we rebuilt the suspension to full moto and ran it in the woods. Did some winter indoor shorttrack at Middletown with the 17"s. Did some ice riding with various wheels and set-ups till I finally thought I had it figured out. Wrong.
So here's the current version, (with more changes in store later).


The only obvious modifications are the additional home-made ice fenders. I made these to comply with AMA rules to cover the wheels above the axles as measured with a string held from the front fender to the rear. Nobody but me has actually held a string up to these to see if they actually comply.


The rear tire is a Chinese knock-off of the Yokohama Super Digger on my KTM. I did my best to copy the screw pattern and angle from that tire. The difference is that for AMA racing you can't shave the tire and you can only use 3/16" screws. The tire works pretty well given those limitations. I built the fenders with scraps of steel I had laying around, I did have to buy a length of 1/8 x 3/4 strap to form the vertical and horizontal hoops.



The front tire is a 19" AMA legal Carlisle that Matt had in his attic. As we have discovered with most of the ice racing stuff in his attic, it works really well! I had tried to build a 21" front, but it wasn't up to the task demanded by the new rear, so on went the 19" tire on the DTX spool wheel that came with the bike. I do plan on building a better 21" wheel that will enable us to have the front brake again, for road course/TT events.

The bike had an inauspicious debut at the Lake George Winter Carnival Ice Races this past weekend. I had just installed a big bore kit (134cc) and I was looking forward to trying my hand at some real sanctioned ice racing. Unfortunately, I overheated the piston during the first practice session, resulting in a seizure as I down-shifted entering T1 at a fairly good clip. After that, the engine lacked compression. I had to load it up and call it a day.

Before I left, I watched this pro heat race, dominated by PJ Jacobsen...
video

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