seems that our bikes are very sensitive to oil level, any noticable feeling between an over filled zx12 and one filled the right way?

whats the perfect level for the big bike?

Years back I tested this on a dyno to view actual hp losses doing back to back all gear pulls.

The bike lost approx. 7rwhp at peak with the oil filled to the top of the sight glass vs just below the 1/2 way mark (as recommended by kawasaki).

I don't have the graphs with me anymore (it was a long time ago) but I do remember the extra oil caused the power flatline at higher RPM's instead of continuing to climb as it went through the gears.

Needless to say, our 12's are very sensitive to oil levels.

I cant give any #'s but I could tell the difference from 10/40 to 20/50 in the Texas heat
. The case cover says 2.8 liters with filter change = 3 quarts US so thats what I run......
It appears slightly less than half way in the sight glass on level ground held at level with respect to vertical....

Does thinner oil make a differecnce also....? Say you had 10/40 at the correct level and then refilled with a thinner grade oil to the same level, would you get more rwhp that way...?

The oil level effects windage in the crankcase, thus robbing power. The thinner grade oil will make an extra hp or two but at the cost of protection. Keep in mind that when oil gets hot, it thins even more and is less capable of protecting crank/rod bushings.

Not worth the trade-off for such a ridiculously miniscule gain, IMO.

thats quite a few horses, time for a fresh oil to the correct level mine is way overfilled 3/4 the sight glass!

I have a modified pan that holds a little extra oil. about half a litre or so approx for added protection/better cooling. so I dont measure, just dump it in till its up to where I feel is ok on the sight glass, about 2/3 makes me feel good for drag racing so I have the extra little bit to make sure I dont suck an air bubble on the launch. going to make a "roof" for my pan this winter so I feel even safer.

On this topic... Do you guys add 3 quarts total (including oil filter) or 3.x quarts to take the oil filter into account?

I use a Pure One 14610 which holds probably 1/3 of a quart. I have been using about 3.25 or so quarts because having more power means less to me than having my bike running next season. ;-)

No wonder I can't beat Shiphteey... LOL

1 liter for me, no more...j/k. I just add a little at the time until I start seeing it at the sight glass with BOTH TIRES on the ground bike straight up and down.

If you like wheelies or maybe frequent the strip with hard launches maybe adding a little more would be a good idea. There is a fine line between lesser oil for less parasitic losses in the motor and spinning a bearing though, be careful if you are trying to go too low.

A.

purchased fresh oil and filter yesterday, so i may be doing the change anytime before the weekend.

should i keep it at 3/4 the sight glass? a bit less?

That would be fine, no real ill effects save for a tiny bit of HP. But if you are after a little more relability and brake hard, wheelie, or drag launch a bit then a little more oil is a good thing for longevity.

A.

I noticed if I just put in the amount called for in the manual 3qts (which is just below the bottom of the sight-glass on mine, while standing up strait) instead of filling it up 1/2 on the glass (like I used to do)... my milage went up like 3mpg.

i have run my bike 1 qt OVER full and still ran the same quarter mile time back to back.. seems not to matter. i use Lucus cycle oil 10-40 synth. i took off oil coooler system and use 3 qts even now.

how consistant are you normally?

Exactly how does that effect the price of tea in China? lol


The dyno graph showed a loss of 7rwhp at PEAK when going through the gears. I don't have the graph on hand to post up, but it flatlined like a table up top instead of continuing to build power. This is due to excessive windage in the crankcase from the extra oil which slows down the internals at high rpm.

In the 1/4 mile, you're primarily in the first few gears which offer the most thrust, allowing the bike to pull the rpm's very easily up to despite a small loss in power. Add that to the fact that you're never at peak power for more than a fraction of a second in those early gears and it's not unusual that you didn't see much or any difference in performance in the 1/4 (if indeed you are extremely consistant and you performed back to back runs in identical conditions with both oil levels, which I highly doubt you did).

Try a 6th gear pull on the highway with both oil levels and you will see a difference in performance up top.

wow, im impressed. I need someone like you on my team. I am pretty consistant if i knew how to post pics i would put sum slips up. good day ill put a pair of 9.51s up and 9.52 or even a 9.54. then BLAM bad light and ill get knocked out by someone having a good day too. always happens. LOL

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