750/4 Forgot Cylinder Stud O-rings

I'm sick to my stomach because I forgot to install the two 8.8mm O-rings that go over the cylinder studs next to the cam chain tunnel on my 750E2. I remembered to use sealer on the stud threads at least.

What do these O-rings do anyway? The later ZX-7 family bikes don't use them at all. I'm wondering if I should tear the top end back down now or gamble and see what happens.

Has it been started yet? If not you should be able to reuse the gasket. It would nag me forever and if it did leak, No one could beat me up more than me. :dry:
Steve

Hate to admit it but I did the same thing, felt the same way and have been trying to forget it........ have 900 miles on it and three years with no leaks..... re torgued at 50 miles after first warm up and cool then again at 600.......... I'm leaving mine alone. Like you say they stopped using them so I hope they figured out they were not needed.

KZB2 650 wrote: Hate to admit it but I did the same thing, felt the same way and have been trying to forget it........ have 900 miles on it and three years with no leaks..... re torgued at 50 miles after first warm up and cool then again at 600.......... I'm leaving mine alone. Like you say they stopped using them so I hope they figured out they were not needed.

Good to hear about no leaks.

I've got a parts engine so I'll look at the crankcase parts tonight and try to figure out why they spec O-rings. Only thing I can think of is that maybe the stud holes interconnect with an oil galley passage. Seems odd that only those two studs are supposed to have the O-rings so something must be going on there.

swest wrote: Has it been started yet? If not you should be able to reuse the gasket. It would nag me forever and if it did leak, No one could beat me up more than me. :dry:
Steve

Don't think I'd be able to reuse the gaskets. I used RTV on both the base and head gasket per the service manual's direction, so you can't reuse the gaskets (typically) because they pull apart when you try to release the clamp load. Oh, engine hasn't run yet. Just installed it in the chassis yesterday.

I don't think RTV will be a problem. Three bond etc might. On the Z1, the 4 outside studs have the oil galleys. The center ones are open and get crap in them all the time.
Steve

Studied some spare crankcase halves and one of the studs goes all the way through to the inside of the engine. In theory crankcase pressure could push oil up the thread clearance and into cylinder. The stud threads are .88" long though, and stud locking agent was used so it's a long shot for oil to get past (I hope). The other stud that is supposed to get an O-ring threads into a blind hole so no way for oil to get up. No clue why Kawasaki want an O-ring on that stud. Could the 650 have two studs that go through?

One other question now: I forgot the rubber plugs that go into the holes in the cylinder. Any consequence of these missing?

I will need to look more but I remember Steele saying he thought they were there cause on that one side the cut out for the chain galley was a little closer (very slightly) to those two studs and that was the reason......someone else forgot his too and asked and he answered and said he thought they would be ok without cause they did away with them a little later like you said ......and the #6 rubber plugs are just the dampening rubber plugs (to keep the fins from vibrating) and are should be cast into the cylinder already..... mine were and in the 750 block I have too.

I'd leave it as is rather than tearing it down again. The main oil leak point in my experience, certainly with the 550's is the top end oil passages at the side of the block and head.

Part 4 on the diagram is superseded with a revised part with shrouding at the sides, I would upgrade on this.

92043-1210

I think I may have made this same mistake, missing those 2 o-rings around the 2 studs. Any update on if this has caused any problems? My bike appears to be running well and no major oil leaks. 

They are only there as those two stud threads are open to the crank shaft cavity. The remainder are blind. The o rings were there to prevent oil making its way past the stud threads but I've never seen it happen with or without o rings. The open thread end is not below the oil level and only gets oil on it from crank rotation throw off. As that cavity is not high pressure its unlikely to force oil past the thread. 

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Warren3200gt wrote:

They are only there as those two stud threads are open to the crank shaft cavity. The remainder are blind. The o rings were there to prevent oil making its way past the stud threads but I've never seen it happen with or without o rings. The open thread end is not below the oil level and only gets oil on it from crank rotation throw off. As that cavity is not high pressure its unlikely to force oil past the thread. 

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That makes sense. So realistically if the oil was getting past the stud threads it would show as oil leakage outside the engine, on top of the head where the head nuts are correct? The base gasket and head gasket should prevent that oil from passing into the cylinder and burning oil?