by slracer-1 » Tue Nov 03, 2009 9:06 pm
Michael, Aren't you supposed to tell somebody if you are planning blackmail? :p That little Yammie went about 89 at Bonneville but the record was more like 94 then! It developed a hunger for the left side pistons but didn't care for the right side. I tried everything I could think of until one day a guy walked up behind me and asked "Eat the left piston? They're always the one to go!" Since the heads were still on the engine, I asked him to sit a spell and chat. (That translates into I chained his leg to my pickup and threatened to drive back to Salt Lake City at high speed if he didn't cooperate!) It was simple enouigh he said, the center main bearing wears which allows the crank to flex a little. That in turn, since the ignition is timed from the end of the crank, advances the left side and retards the right. The left then "hand grenades"! Since GYT pistons are somewhat hard to find, I haven't rebuilt the motor since. The new toy has an engine compartment sized to hold this engine as you just haven't lived until you hear a 100cc twin at full song turning about 16,000 rpm in the intermediate gears. I don't know about top gear as the engine never lasted that long! ??? If anyone has a source of GYT pistons that fit a 1972 Yamaha LS-2, please let me know.
The last shot (which appeared in a Japanese road race magazine and a Japanese Kawi club magazine) shows the original configuration of the 1974 Kawasaki KM-100 (my first race bike). The gas tank was moved behind me and I laid down on a flat seat (looking for an areo benefit). Even though I put the petcock at the aft end of the tank (so the acceleration of the bike would force the fuel aft and then forward to feed the engine) I had fuel feed problems. The first shot shows a more conventional tank arrangement. This tank was way bigger than necessary and I only used about 1/3 of the total volume (on one side). Aero devices are not allowed in this class, but a gas tank is so the big tank was another experiment. I cut the top off so I wouldn't be too high and added the yellow padding as a cover. At the end of the run, I could get a drink out of my glove box (which was the other side of the tank). This bike actually went 93.465 at Muroc Dry Lake (aka Edwards Air Force Base) and set a class record. That record may never be broken as 9-11 resulted in the track being "off limits" to civilians again (WW2 did the same thing). I did add a suitable aft fairing to provide clean aero at the rear. Our rules only classified it as aero if it was a device "in front of the rider". Plans for the new toy also include this engine (especially if I can't find pistons for the Yammie). A lot of memories in those pics, Thanks Michael! -- Doug
PS - Those leathers were once owned by the national champion Speedway rider!