Ducati Missle Launcher One fine afternoon, one of my closest riding buddies and I were cruising through suburban Jacksonville, Florida, enjoying the life of young teenagers—me on my 50cc Honda C110, and he on his 125cc Ducati Bronco. Other than our bikes, we didn’t have much, nor need much. POW! All of sudden, out of nowhere, a loud pop and an unidentified flying object whistles past my head. Warren slows and pulls over. A thorough investigation reveals his mighty Ducati has lost its spark plug. After pushing his bike home, we take stock of the situation. The threads had completely blown out of the head, along with the spark plug and cap. A new cylinder head is prohibitively expensive. A good, used cylinder head is not only unavailable to us, but also expensive. The only head Warren could afford was the stripped one he already had. We must repair it. Even inexperienced teenagers can take things apart. Once the head was in our hands, we set out to have the wallowed-out hole repaired. In our neighborhood was a family of serious sports car racers. They had a race car transport that stayed in the driveway, and Porsches with numbers on them parked about the property. Never had we set foot in their garage, as they were sooo much more sophisticated than we, that we felt unworthy.
As Warren and I carry the culprit head into the Porsche race shop, we are encouraged to see a full machine shop that most assuredly will be the answer to our prayers. Grown up racers look at our problem, confer amongst themselves, then inform us that the hole is too close to the valve seat and not enough metal left for repair. “The head needs to be replaced.” We are crushed. With nothing to lose, we develop a plan to repair the head ourselves. We scrounge a piece of aluminum bar just a bit bigger diameter than the ruined hole, then cut to the length needed to end up flush inside the combustion chamber, and flush to the spark plug seat on the outside. We then painstakingly file by hand the head and aluminum slug to a press fit. We reasoned we could make it tight enough to contain combustion if we could somehow keep it from blowing out. Once the plug was pressed into place, we cross-drilled the head, directly through the plug and drove a 1/8-inch steel rod into the hole, cutting it off flush at the head gasket surface. The Duc was originally fitted with a larger, standard diameter spark plug, 14mm, I think. There was not enough metal for new threads to be cut. My little Honda was outfitted with a 10mm spark plug, and if used, that could leave enough meat to allow for new threads. We didn’t have a 10mm tap of course, but we did have two used 10mm spark plugs. One was saved for Ducati street duty, and the other was converted to a homemade die. We filed flutes into the threads, then heated and quenched our new die. Carefully, we cut our new threads, and reassembled the little OHV engine. She fired right up with no ill effects. It was a joy to ride down to the Porsche shop and show the big boys what we had done; they shook their heads at our unorthodox (but effective and affordable) repair. The Bronco ran as good as ever, until Warren finally sold it a year later. Where there is a will, there is a way. – Arthur Kowitz AHRMA Chairman of the Board 386.547.9504 dbsuperbiker@gmail.com
IN This Issue
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Chairman of the Board
6
Executive Director
7
My First MX Race
RR Director
7
Aonia Pass CC/MX - A Personal Recap
Off-Road Director
8
TOOL BOX TIP - HOT PIT Tool Box
Back in the Saddle
8
Blast from the Past 34
Bodnar Ranch VMX/Trials
10
The 110 MPH Husky
36
Twilight Farms - Regional CC 14
2020 National Series Schedules
44
LeMay - Regional Trials 18
Race Previews
46
My Fiona 20
2020 Regional Series Schedules
50
Ashcraft Farms - Regional MX/CC 22
Membership/Race Forms
56
South Central Regional Update 26
Marketplace / Swap Meet
67
6
WWW.AHRMA.ORG
34
32
AMERICAN HISTORIC RACING MOTORCYCLE ASSOCIATION
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AUGUST 2020
