Racing gears

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Racing gears

Postby Emerica1975 » Thu Jun 02, 2022 1:11 am

Over the past year while I’ve been rebuilding my st165 I’ve heard and read racing gears. And this has got me wondering what is the history of people racing and making these bikes to race over the years.
Any info would be awesome!!
Thanks
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Re: Racing gears

Postby badger34 » Fri Jun 03, 2022 10:58 am

There is some oval track, TT and even hill climbing history but I would say they were most popularly used for off-road endurance competitions. Keep in mind they most often competed in a specific lightweight class separated from middleweight and heavyweight cycles. Most famous I would say is Leroy Winters' 1956 overall champion Jack Pine victory on a 165cc, a web search will provide some info.
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Re: Racing gears

Postby pumpguy » Fri Jun 03, 2022 11:54 am

Back in the early 1960s, in addition to commuting back and forth to work, we were racing our 55 125 Hummer in scrambles and enduros.

There was a booklet published by Floyd Clymer titled SOUPING TWO-STROKE ENGINES FOR MORE SPEED AND POWER - How To Get 10 HP From Your 125. Lots of interesting info there but pretty primitive by today's standards. Booklet contains info on larger carbs, stuffer plates, cylinder and head mods.

I was talking to a Kart racing tuner and he said "You need a reed valve". I thought about putting a pyramid reed valve between the carb and cylinder, but never got around to that. Just a couple of years later Yamaha did that very thing.

Around that same time I noticed an ad in the British magazine Motorcycle Mechanics by George Todd offering high compression heads for 125 BSA Bantams, so I ordered one. It was a direct bolt on fit. Not as large finned as Pucketts heads, but still bigger than stock and had a central spark plug tapping. Later I ordered a whole batch semi-machined, finish machining them myself to whatever compression ratio and chamber shape the customer wanted.

An online search for GEORGE TODD and 125 BSA BANTAM will reveal more details.

Leroy Winters' Jack Pine winning 165 was fitted with a special swing arm rear suspension made by Wrights Springer Products in Florida, a feature Harley did their best to hide in their ads. You read a lot about lightweight 2 strokes like Bultaco and KTM revolutionizing dirt bike completion, but Leroy Winters 165 is where it really started.

Later we were running a 165 and ended up getting what was almost certainly Wright's last swing arm kit. Couldn't afford the shocks too, but had a pair of shocks from a 175 Puch / Allstate so used them. They were too long so we heated and bent the upper frame mounts so they'd fit. They worked just fine.

We sure had a lot of fun.
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Re: Racing gears

Postby Emerica1975 » Fri Jun 03, 2022 2:37 pm

That’s great stuff!! Is it still possible to find any of the old race parts (heads, gears,etc) for purchase? It would be awesome to build and run bikes like that.
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