KZR's Bikes of the Month for 2024

750/4 Forgot Cylinder Stud O-rings

  • Nessism
  • Topic Author
  • Offline
  • Sustaining Member
More
05 Oct 2015 04:57 #693404 by Nessism
750/4 Forgot Cylinder Stud O-rings was created by Nessism
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.

Please Log in or Create an account to join the conversation.

  • SWest
  • Offline
  • Sustaining Member
  • 10 22 2014
More
05 Oct 2015 05:27 #693411 by SWest
Replied by SWest on topic 750/4 Forgot Cylinder Stud O-rings
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

Please Log in or Create an account to join the conversation.

More
05 Oct 2015 06:08 #693419 by KZB2 650
Replied by KZB2 650 on topic 750/4 Forgot Cylinder Stud O-rings
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.

1978 KZ650 b-2
700cc Wiseco kit 10 to 1.
1980 KZ750 cam, ape springs, stock clutch/ Barnett springs.
Vance and Hines Header w/ comp baffle and Ape pods, Dyna S and green coils, copper wires.
29MM smooth bores W/ 17.5 pilots, 0-6s and 117.5 main
16/42 gearing X ring chain and alum rear JT sprocket.

Please Log in or Create an account to join the conversation.

  • Nessism
  • Topic Author
  • Offline
  • Sustaining Member
More
05 Oct 2015 06:38 #693422 by Nessism
Replied by Nessism on topic 750/4 Forgot Cylinder Stud O-rings

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.

Please Log in or Create an account to join the conversation.

  • Nessism
  • Topic Author
  • Offline
  • Sustaining Member
More
05 Oct 2015 06:48 #693425 by Nessism
Replied by Nessism on topic 750/4 Forgot Cylinder Stud O-rings

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.

Please Log in or Create an account to join the conversation.

  • SWest
  • Offline
  • Sustaining Member
  • 10 22 2014
More
05 Oct 2015 09:22 #693445 by SWest
Replied by SWest on topic 750/4 Forgot Cylinder Stud O-rings
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

Please Log in or Create an account to join the conversation.

  • Nessism
  • Topic Author
  • Offline
  • Sustaining Member
More
05 Oct 2015 16:40 #693510 by Nessism
Replied by Nessism on topic 750/4 Forgot Cylinder Stud O-rings
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?

[IMG

Please Log in or Create an account to join the conversation.

More
05 Oct 2015 17:43 - 05 Oct 2015 18:18 #693523 by KZB2 650
Replied by KZB2 650 on topic 750/4 Forgot Cylinder Stud O-rings
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.

1978 KZ650 b-2
700cc Wiseco kit 10 to 1.
1980 KZ750 cam, ape springs, stock clutch/ Barnett springs.
Vance and Hines Header w/ comp baffle and Ape pods, Dyna S and green coils, copper wires.
29MM smooth bores W/ 17.5 pilots, 0-6s and 117.5 main
16/42 gearing X ring chain and alum rear JT sprocket.
Last edit: 05 Oct 2015 18:18 by KZB2 650.

Please Log in or Create an account to join the conversation.

  • Tyrell Corp
  • Offline
  • User
  • "You were made as well as we could make you"
More
09 Oct 2015 03:21 - 09 Oct 2015 03:26 #693898 by Tyrell Corp
Replied by Tyrell Corp on topic 750/4 Forgot Cylinder Stud O-rings
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


Attachment T2eC16dHJHFFmD-46qBRuK5Ditkw60_35.jpg not found


1980 Gpz550 D1, 1981 GPz550 D1. 1982 GPz750R1. 1983 z1000R R2. all four aces
Attachments:
Last edit: 09 Oct 2015 03:26 by Tyrell Corp.
The following user(s) said Thank You: KZB2 650

Please Log in or Create an account to join the conversation.

More
08 Jul 2024 07:06 #901886 by sflesch94
Replied by sflesch94 on topic 750/4 Forgot Cylinder Stud O-rings
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. 

Please Log in or Create an account to join the conversation.

More
08 Jul 2024 07:51 #901887 by Warren3200gt
Replied by Warren3200gt on topic 750/4 Forgot Cylinder Stud O-rings
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. 

​​


Z1000J2 somewhat modified!

The following user(s) said Thank You: sflesch94

Please Log in or Create an account to join the conversation.

More
08 Jul 2024 08:31 #901888 by sflesch94
Replied by sflesch94 on topic 750/4 Forgot Cylinder Stud O-rings

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. 

​​
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? 

Please Log in or Create an account to join the conversation.

Powered by Kunena Forum

If you like KZR Please consider making a donation. Thank you.

KZRider is free, but not without cost.

Please consider chipping in a few bucks to help cover the cost of running the KZR servers.