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Old 01-23-2008, 08:01 AM   #52
Gnarly Adventurer
Joined: Dec 2006
Location: santa cruz, ca...
Oddometer: 402
before power valves...

Originally Posted by motu
The other big step after monoshock was power valves on 2 strokes.This transformed totaly violent instant snapping powerband bikes like the Husky into bikes with power from idle until your vision got blury.It was very hard to ride those powerband bikes....or at least for mere mortals like me.You had to get the bike lined up and pointing somewhere safe before you opened it up.It was like walking in front of someone swinging a length of 4x2 behind knew it was going to connect sometime,'twas scary.
back up a half a decade, pardner.

first there were reed valves.

before that, there were plain ol' piston port inductions or rotary valve intakes. god, i'd almost forgotten the days of accidentally loading up a bike and having to sit there with the throttle wide open while the bike popped and sputtered and cleared itself. yamaha were the ones who widely popularized reed valves, although the CR honda was the first legitimate jap MX bike and the repercussions of its introduction led to the rest of the japanese going crazy.

as a result of the CR coming along, within three years of 1973, suzuki had gone from those hideous side-hopping TMs to the new RMs (and their factory bikes were winning world championships in all 3 classes) and yamaha had ditched the DT derived MX line and come out with the totally cool monoshock YZ bikes. everyone except honda was using reed valve engines, and the suspension race was fully on.

it's kind of a trip to look back and see how bikes went from about five or six inches of travel around 1975 to a foot of travel by 1980-1982. also, trippy to see that by 1982, the ONLY manufacturer still using twin shock rear suspension was Husky.

the power valves were the next step - early 80's - as the suspension revolution settled down, water cooling came into play, then power valves followed suit.

then things sort of smoothed out for a decade or so until some jackasses decided to bring four strokes back...
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