Tony Nitrous
31-05-2011, 04:48 PM
Pic's and Info stolen from a US Hayabusa site......
I designed and had made enough parts for 5 1900cc engine back about
7 years ago. The parts required were a 71.5mm stroker crank with rod
centres moved out to 94mm centres. 91mm pistons, with valve offsets
to suit stock head, billet barrel, much taller to accommodate longer
rods, longer head studs, longer cam chain and new clutch basket and
clutch gear moved round the basket to mate with the new position of
the crank primary gear. Well I built one motor and ran it on the
dyno with a stock head, reground cams and a one off exhaust, it made
260 bhp and 160 lb/ft of torque. I ran it at one airfield drag meet
with an almost stock bike (4 inch over). With lots of wheelies i
pulled several 9.7's all over 157mph. Stripped the motor the next
week and found the crank manufacturers had made an error which had
caused the thrust races to be squeezed out of place.
http://img23.imageshack.us/img23/561/19011p.jpg
There's 4mm between the cyl. It's billet not cast, even though it
looks cast. It looks that way as the bore plating was etched off and
then replated as there was a problem at the platers. the result was
they etched the outside to. Peak power was at 8k even though it
still revs to 11k. Boost would be pushing your luck maybe. My other
cylinders are not bored right out yet and I think I can squeeze a mm
more offset to get more bore to bore wall clearance.
http://img36.imageshack.us/img36/3788/19022.jpg
Cylinder head has to have waterways welded up as they are in the chamber!
240 whp and 155 lb.ft torque.
http://img695.imageshack.us/img695/1100/19033.jpg
I designed and had made enough parts for 5 1900cc engine back about
7 years ago. The parts required were a 71.5mm stroker crank with rod
centres moved out to 94mm centres. 91mm pistons, with valve offsets
to suit stock head, billet barrel, much taller to accommodate longer
rods, longer head studs, longer cam chain and new clutch basket and
clutch gear moved round the basket to mate with the new position of
the crank primary gear. Well I built one motor and ran it on the
dyno with a stock head, reground cams and a one off exhaust, it made
260 bhp and 160 lb/ft of torque. I ran it at one airfield drag meet
with an almost stock bike (4 inch over). With lots of wheelies i
pulled several 9.7's all over 157mph. Stripped the motor the next
week and found the crank manufacturers had made an error which had
caused the thrust races to be squeezed out of place.
http://img23.imageshack.us/img23/561/19011p.jpg
There's 4mm between the cyl. It's billet not cast, even though it
looks cast. It looks that way as the bore plating was etched off and
then replated as there was a problem at the platers. the result was
they etched the outside to. Peak power was at 8k even though it
still revs to 11k. Boost would be pushing your luck maybe. My other
cylinders are not bored right out yet and I think I can squeeze a mm
more offset to get more bore to bore wall clearance.
http://img36.imageshack.us/img36/3788/19022.jpg
Cylinder head has to have waterways welded up as they are in the chamber!
240 whp and 155 lb.ft torque.
http://img695.imageshack.us/img695/1100/19033.jpg