Sunday, January 23, 2022

KX500 Trackmaster





 I have been saving a Trackmaster frame for about 5 years now. Good old Tommy bought it from Jim Henry and gave it to me to do something with. Jim Henry was the first person to help me out on the old Flattrack.com forums when I started building my XS. He set me straight on my maiden voyage into flattracking selling me a front to rear wheel quick change adapter and a seat. Thanks to him my XS was a well set up and behaving racer right from the get go helping me immerse myself into the sport of flattracking. Right after Tommy bought it Jim passed away. Maybe a year after the 80+ year old brakeless class racer had one gnarly get off at Stockton 1/2 mile. Tommy and I thought about putting an XS twin engine in the frame but I found out the frame was originally built for a single two stroke engine. The engine mounts had been heavily molested so I thought a lighter engine might be better, knowing my less than great welding on top of previous less than great welding added to a heavy 80 HP engine might go over like the Hindenburg. It sat. I moved. Tommy died. Rest in peace my Cosmic Cowboy amigo. A special frame awaiting a special engine. I thought of retiring it to a street tracker cradling the Gt550 2 stroke triple I have hoarded. I thought of another CRF450 framer. Then looking at it one day it hit me that I had a 1987 KX500 engine horded away awaiting a special frame. I learned some of the KX500 engine mojo tuning when building the KX500AF and it's stock frame sister build a few years ago. A powerful light engine in a classic known dirt oval track weapon. It won't be vintage class legal so the Durrell racing forks hoarded find themselves a worthy home along with a spare nice old heavy XS rear(old front) mag wheel with quick change adapters the Ranum bros machined up using my old Jim Henry as a model.    First I cut the swing arm out and boxed it to accept modern wide rear tires. I fit the engine with the counter shaft as low as possible in relation to the swing arm pivot. Both the swing arm and motormounts are the first tig welding I have ever done not on aluminum and I am amazed how much fun tig welding steel is rather than aluminum. Much easier but still my weld quality leave much to be desired. For the past week now I have been masochistically torturing my ADD ridden, math class flunky of a brain with designing an expansion chamber.... Wish me luck.  

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