my 90hp (at asphalt) '82 GPz750 (810)
Posted: Tue Mar 15, 2011 4:35 am
i used to have (& probably still do somewhere) dyno charts, just looked & couldn't find them (found a clutch cover gasket though...LOL)
anyway the torque was good...knife edging is considered a "medium" lightening of the crank that also decreases the physical resistance of the oil
as a matter of fact i replaced it with a stock crank at one point due to friends spouting the torque argument & the bike was noticeably slower
i had 2 810's for that bike as i also purchased a crashed '83 KZ 750 that only had the Wiseco's & street porting...otherwise stock
the KZ mill was good but nowhere near as much fun as my stand straight up on the throttle at 6 grand motor
actually i lucked out with the good motor as i bought an '82 mill that had been built for Daytona that had some wild bits
the head had wide open high RPM porting & it & Andrews blank cams had been sent to California & the cams ground to suit the head
the cams had such a high lift that some meat had to be taken off the head so they had room to turn & the valve stems & spring retainers were shortened
i installed larger intake valves...decked the head a little & decked the barrels a lot & ported the Z intake rubbers to blend them with the head for the 29mm Mikuni smoothbores
shimmed the oil pressure relief valve & knife edged the crank with balanced rods & pistons (810cc)
of course the timing plate was slotted & advanced...& i switched to a bigger oil cooler (Zephyr 750 i think)
that's what i call a sleeper...LOL
the only problems were maintaining sufficient oil pressure to resist the thrust on the big end rod bearings 2&3 due to the cylinder squirt holes in the GPz rod & top bearing...resolved this issue by putting the bottom bearing in the top thus blocking the hole
& the cams would break shims occasionally...LOL...no big deal with underbuckets, they were still there
the reason i mentioned the crank is i personally wouldn't even consider NOT knife edging due to my own experience with a bike i rode for 20 years....
the smooth bores are gravy....really really good gravy after 6000rpm though
anyway the torque was good...knife edging is considered a "medium" lightening of the crank that also decreases the physical resistance of the oil
as a matter of fact i replaced it with a stock crank at one point due to friends spouting the torque argument & the bike was noticeably slower
i had 2 810's for that bike as i also purchased a crashed '83 KZ 750 that only had the Wiseco's & street porting...otherwise stock
the KZ mill was good but nowhere near as much fun as my stand straight up on the throttle at 6 grand motor
actually i lucked out with the good motor as i bought an '82 mill that had been built for Daytona that had some wild bits
the head had wide open high RPM porting & it & Andrews blank cams had been sent to California & the cams ground to suit the head
the cams had such a high lift that some meat had to be taken off the head so they had room to turn & the valve stems & spring retainers were shortened
i installed larger intake valves...decked the head a little & decked the barrels a lot & ported the Z intake rubbers to blend them with the head for the 29mm Mikuni smoothbores
shimmed the oil pressure relief valve & knife edged the crank with balanced rods & pistons (810cc)
of course the timing plate was slotted & advanced...& i switched to a bigger oil cooler (Zephyr 750 i think)
that's what i call a sleeper...LOL
the only problems were maintaining sufficient oil pressure to resist the thrust on the big end rod bearings 2&3 due to the cylinder squirt holes in the GPz rod & top bearing...resolved this issue by putting the bottom bearing in the top thus blocking the hole
& the cams would break shims occasionally...LOL...no big deal with underbuckets, they were still there
the reason i mentioned the crank is i personally wouldn't even consider NOT knife edging due to my own experience with a bike i rode for 20 years....
the smooth bores are gravy....really really good gravy after 6000rpm though