Q. with all the hype about zx-12s and oil levels, do you have any info on zx-7s? in other words, if I fill my crank-case to where my sight glass says it’s full, do you know if my crank and con-rods are actually splashing around in the stuff at operating revs?? maybe I’m just being paranoid, but I’ve always filled my bikes to half-way between the “full” and “add” lines. Also, have you ever seen any hp gains using “knife edge” con-rods?
A. I’m going to be dynoing a ZX-12 this weekend, and am going to try different levels of oil to see if those reports are true. Will report back. On my 93ZX7 R you can be sure I have tried different levels of oil and it made NO difference. I generally however run my oil level right in the middle of the sight glass.
NOW GET THIS, I once was running the bike on the dyno with a 75 horsepower shot of nitrous and thought I blew the motor when oil went everywhere. What had happened was the crankcase so overpressurized it force the oil sight glass right out of the clutch cover socket. I never even knew this was a replaceable item (SIGHT GLASS). There is a Part # for it! So if anyone doesn’t think crankcases cant become pressurized under extreme circumstances, here’s proof. That’s why I went to the EVAC system I described and I now safety wire my sight glass in by drilling two holes, one on each side and use the safety wire to hold it in. This has worked great.
the check valve can be purchased from PEP BOYS, its a BORG WARNER A/P check valve, and the part # is CV 2.
Knife edged con rods do work. They are used in all of the NASCAR engines. In fact most of the recent HP gains in Cup cars the past few years have come from reducing oil windage. APE knife edges all the cranks I get done by them and this flat works.
I mention NASCAR a lot in my postings, I grew up with a father who was a Winston Cup Engine builder which is were I learned all this. Those guys are the best engine builders in the world. They get so much from so little. It really is amazing. But the neat thing is, ENGINE DYNAMICS are the same for everybody! We can do just as good as the next guy if we try hard enough.