Help - Crank oil seal question???

Hey gang - Need an answer asap on this crank seal question.

The bike is a '77 Kz650 and the right side oil seal on the crank is leaking a bit. The seal sits behind the points plate area. There is a small lip on the middle part of the seal's exterior contact surface and it seems to fit into a groove on the inside of the cases.

I just changed the seal last month when I had the motor out of the bike to do the 810 rebuild but it seems that perhaps I got a damaged seal from Kawasaki or I pinched the seal when installing it. Needless to say, I don't want to have to pull the motor again for a simple seal.

So, can this seal be changed without having pull the motor and splitting the cases? T Can this be simply and carefully pressed in?

Any experienced advice would be appreciated.

Cheers-Colin Firth -Ontario Canada
'1977 Kz650 Custom - built to run hard.

IIRC, the crank has to be lifted out of the case to get that seal off, don't think you can do it any other way.

I have never paid much attention to the 650 but on a 900/1000, there ain't a seal on the cases. The seal is on the inner points cover. The crank goes through the seal on that cover and that is where engine oil is retained. To change the seal, you just pull off the inner points cover. Hopefully, the 650 configuration is the same...

#17 and #18 are the crank seals.


Post edited by: steell, at: 2006/06/24 00:12

I stand corrected. I can't understand why seals are needed where shown. Does the crank come through the cases on both sides? If so, isn't there a seal on the inner points cover as well (on right side) and have the stator cover with a gasket on the other side? If so, why are these seals needed. Not arguing, just curious. Do they sit around the crank and have the engine cases scrunch down on them?

The 650/750 cases are different than the 900/1000 cases, there is no drain back hole in the stator area so any oil there would be trapped, and the right side seal is directly behind the points plate. In the pic you may be able to see the grooves in the case that the seals fit in.

Thanks gang for your input. Here is what have discovered with my leaking seal which seems to have a small pinch on the front part that is causing a tiny leak at higher rpm.

The crank seal bearing is a pretty tough piece of rubber with a steel wire ring inside, kinda like a radial tire with cords. The bearing has a little raised lip the in the center part of the outer ring circumference.

To properly install the seal, the cases definitely have to be be split which involves pulling the motor from the frame, draining the oil and dropping the bottom half of the cases. This is a big headache since I just got everything back together a couple of weeks ago:)

In speaking with an experienced Kz mechanic/racer who campaigns a 900 and 650, he came up with a little, simple solution for me. It is kinda funny but it worked at stopping the oil coming from the base of the points cover.

Okay, are you ready for this???? He suggested using a Kotex pad (ladies sanitary napkin) to absorb the little oil leak. (I am sure there will be a few jokes about this but it worked great!)

I cut a small piece of the absorbent pad and fastened it inside the bottom of the points' cover. It fit in rather snug and will not shake itself loose.

I went for a good ride yesterday (boy does this thing scream with the 810 Wiseco kit) and not a drop came out onto my engine or pipe so the pad did its job. I will keep an eye on how much oil is being absorbed by the pad and change it ....monthly as needed

I've got a new seal coming in from Kawasaki on Monday and I will remove the tiny lip on the seal and press it into place, very carefully. This should hopefully get me through this riding season. Next winter I will pull the motor and split the cases then if needed.

Cheers-Colin Firth
1977 Kz650 Custom. 810 Wiseco, 750 Cams, springs, valves, Dyna, WG Mikuni 28's and lots of other go-fast goodies.