By: David L. Morrill
@Mototique Racing
Ocala, Florida
When I first built the blanked off 1921 Harley-Davidson motor for my racer back in 2010, I couldn't make up my mind, whether to use the front, or rear cylinder. I mocked up the motor both ways, and really liked the rear cylinder configuration.
My rear cylinder had a nasty gouge in the lower bore, where a wrist pin had come adrift, way back when. That wasn't a problem, as I was planning to have the cylinder bored, and use a modern aluminum piston. I checked with my parts supplier, but they said they were out of stock on the piston I needed, and it would be at least 6 months before they got a new supply. I was impatient to get the project moving, so I searched through my parts stash, and found a usable original iron piston & rings, along with a front cylinder with a good bore. I ran a hone through original tapered bore, and everything fit nicely, so the decision was made for me.
I ran the front cylinder set up in Sons of Speed races for 2018 and the March 2019 race. After the March 2019 race, I started looking for a little more speed. One day, I was digging through my spare parts, and found another rear cylinder. the bore on this cylinder was near perfect, but it had a crack in the exhaust valve seat.
After checking with several knowledgeable motor builders, the consensus was that the cylinder could not be repaired. I had met Michael Lange at one of our races, and after seeing this photo of crack, he said he could repair it. Michael did a great job, and a very reasonable cost.
I ran this set up in the October 2019 Sons of Speed races, and the bike ran faster than ever!
Once again in my heat race, I lined up against a field of V Twin racers with twice the engine displacement of mine. I held on to third place, the final transfer spot to the final, for 4 laps, before Shawn McLean passed me on his beautiful Indian Power Plus twin and went on to third place. The March 2020 race will feature a new 30.50ci. -500cc single cylinder class. Woohoo! No more chasing V twins with twice the motor!
When I first built the blanked off 1921 Harley-Davidson motor for my racer back in 2010, I couldn't make up my mind, whether to use the front, or rear cylinder. I mocked up the motor both ways, and really liked the rear cylinder configuration.
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| Rat Racer - Rear Cylinder Mockup |
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Warren Lane's True Grit Vintage Bike Show
Destination Daytona - October 2017
Photo by: Michael Lichter
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| Cracked Exhaust Valve Seat - Bottom Left |
After checking with several knowledgeable motor builders, the consensus was that the cylinder could not be repaired. I had met Michael Lange at one of our races, and after seeing this photo of crack, he said he could repair it. Michael did a great job, and a very reasonable cost.
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Rat Racer - Rear Cylinder Set Up
January 2020
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2019 Biketoberfest Sons of Speed Race @ New Smyrna Speedway
Photo by: Jim Dohms - Dohms Creative Photography
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Once again in my heat race, I lined up against a field of V Twin racers with twice the engine displacement of mine. I held on to third place, the final transfer spot to the final, for 4 laps, before Shawn McLean passed me on his beautiful Indian Power Plus twin and went on to third place. The March 2020 race will feature a new 30.50ci. -500cc single cylinder class. Woohoo! No more chasing V twins with twice the motor!
Rat Racer - Race Ready January 2020
Come out and watch us:
2020 Daytona Bike Week Sons of Speed Races
2020 Daytona Bike Week Sons of Speed Races
Saturday March 7, 2020 - 5:00 PM.
New Smyrna Speedway
New Smyrna Beach, Florida
Sources:
Jim Dohms - Dohms Creative Photography
Michael Lichter