[DeTomaso] NPC: Kenny Roberts TZ750 reunion ride

mikeldrew at aol.com mikeldrew at aol.com
Sun Dec 20 20:25:26 EST 2009


Hi guys,

Strictly motorcycle content here.   

One of the most spectacular races in all of motorcycling history took place 
in 1975 at the Indy mile dirt track.   The legendary Yamaha rider Kenny 
Roberts was desperately trying to hang onto his #1 plate, while Harley riders 
were moving up in the standings and were poised to take it away from him.   
The old Yamaha four-stroke was no longer a match for the souped-up Harleys, 
so some radical thinking was in order.

Yamaha turned to their formidable two-stroke TZ750 Formula One machine, 
whose engine was basically formed by grafting a pair of RD350 race engines 
together to form a 700cc (later 750cc) two-stroke inline four with reed 
induction.   Initially producing upwards of 90 hp, it was later bored out to 750 cc, 
and otherwise leaned on to generate as much as 150 hp, with a brutal, 
wicked, narrow powerband typical of two-strokes.

The idea of attempting to introduce such a weapon into a dirt track bike 
was radical indeed, but the gifted tuner Kel Carruthers spirited one of these 
engines away and shoehorned it into a Champion flat track frame, and had it 
up and running in only five days.

The first time Kenny Roberts saw the bike was when he arrived at Indy to 
race it.   With no proper development, it was virtually unrideable--and 
blindingly fast.   Starting from the last row, he carved his way through the pack, 
wrestling this lethal machine and passing through the field like water 
through a screen door, then making a heroic last-lap, last-corner pass to move 
from third position to take the victory by a margin of about two feet.

Epic stuff.

The bike was so dangerous to ride that Carruthers worked with the AMA to 
get it banned almost immediately, and it became a footnote in flattrack 
history.

A few weeks ago, Yamaha invited Roberts to come sample the bike (actually a 
modern recreation) that propelled him to his greatest ever victory, and 
they made a five-minute film about it.   Well worth watching even if you're not 
a motorcycle guy....

http://www.youtube.com/watch?v=8k8hJWKIVNs

Mike



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