Topic: Cb750 K0 -oil gallery plug under shifter cover?

[Magpie]

Another K0 question - my K0 engine is leaking oil from the shifter cover quite badly and after pulling off the cover and tearing the gasket of course, I notice an oil gallery, I think it is, the goes right under the engine through the case. I looked at a spare set of cases I have and there's a plug in that gallery. Should the K0 have a plug there? I honestly didn't notice it there on my other K0's but really dodn't want to take the cover off one of those and tear another gasket.
Plus, after looking at the picture there's a small crack at one of the screw holes for the cover. All the screws do tighten down and it looks like the thread start down in the hole.
Do you use some sealant on your gaskets to help stop this?
Thanks is advance.
Cliff.

[MRieck]

A rubber plug goes in there.

[mick7504]

Those rubber plugs are a trap if they come out unknowingly.
I don't think that they are listed as a part by Honda from memory.

Previously I've machined an aluminium truck brake shoe rivet to an interference step fit in the hole and then sealed it in with 3 bond.

[Magpie]

There's no reference to it in my parts book. If I made a plug it better not get sucked back into the engine or is it an outlet hole so the oil is pressured at that point then? Thanks, Cliff.

[ekpent]

Cliff I think you will be fine if you stuff in Wrigley's chewing gum,or Beechnut, but do not use the Bubble stuff,she will Blow---------    Merry Christmas and glad to see your getting those hands,and Dog dirty also,saw that cute pooch in your other video thread  on the start-up  ---- 

[Magpie]

Spearmint or Peppermint?      Cliff.

[ekpent]

I have read on 'other' forums that Cinnamon might be best 

[Magpie]

yuch! 

[ekpent]

Did find these pics in an official manual,looks like a gasket goes over that hole.Not much help but we do like the pictures.   E

[Magpie]

Yes, the gasket just covers the hole but I guess they figured to stop any problems in the later motors with a plug. The later one has a raised edge which fits into a recess around the hole. As Mick said I guess I can make one up and glue it in there. cliff

[ekpent]

Show us some pics for future reference Cliff on your fix as I and a lot of others may have to refer to that sometime.. What year engine are you into right now anyway? 

[Magpie]

It's a 12/69 Eric, in the 16000 range.  Cliff.

[Magpie]

I could ask the Sandcast guys, there's some fellows there that are scary in the knowledge they have of these bikes. Cliff.

[Kevin D]

This is a K1, but pretty sure its the same. I think thats the oil line from the scavenge pump to the trans/clutch. I remember reading a thread where the line got blocked when the plug was pushed back in a ways then the trans/clutch was starved for oil. If the plug isn't where it is supposed to be, I'd make sure it wasn't in that line somewhere.

Sorry for the dirty/leaky motor picture:

[MRieck]

Yes, the gasket just covers the hole but I guess they figured to stop any problems in the later motors with a plug. The later one has a raised edge which fits into a recess around the hole. As Mick said I guess I can make one up and glue it in there. cliff

If you do that check the length carefully so you do not block the trans feed galley. As an aside I have seen the main galley plug (under the alternator gasket) missing upon disassemby. Not good.

[mick7504]

Like Mike said, be carefull not to block the oil feed gallery to the trans bearing.

Here you can see the take off port.



This is the oil pump area.



The next 2 are the cross tube and the plug on the other end of the engine case.
These are on a set of "F" cases but I think that they should all be similar if not the same setup as the "K".

[MRieck]

Excellent pics as usual Mick. The last pic showing the aluminum plug is interesting as it is just about impossible to bang out of there. In my pursuit of a complete case douching I have drilled into the plug and tapped it for a 6mm Allen head bolt with a copper washer. I safety wire it after.

[Magpie]

Great information as usual, thanks guys! I found that little gallery just inside the hole with a much more powerful light late last night and checked the pictures of the other motors I have worked on. However all the motors have been apart previous to me working on them. It appears the plug is an upgrade then and the engineers hoped the gasket would prevent any oil leaking.   I though the stator gasket was leaking as well but once I got the shifter cover off the stator gasket was dry in there. I took the precaution of putting a bit of Permatex on the rubber bungs that the wires run through. the oil from the shifter cover leak must have run down the bottom of the engine towards the front. It was a good amount of oil coming out and burning off on the exhaust pipe.
There is a danger then of making a plug that would eventually plug the oil passage just inside the hole and help end the life of a good motor.
Could all this come down to a poor gasket and OE, operator error, a poor gasket install? 
Hondaman suggests putting a bit of the 3Bond or something like it on the gasket.
thanks again, Cliff.

[markb]

Replying so I can find this thread later.  I gotta check this out on mine.  I don't think I was ever aware of it.   

[CB750F2]

The plug is identified in the F2 parts breakdown. Page E14 -Crankcase N0.2 Part No. 11209-300-000 Plug, Sealing Rubber, 8.5mm. Pat

[Magpie]

Thanks Mark! It will be interesting to see what yours are like. If there is a plug it's a special one as it's not a round hole, there's a flat spot on one side. In the newer case it as a round hole.
Cliff.

[markb]

This has really got me scratching my head.     I happen to have 3 sandcast cases apart that I looked at, 100, 1490 and 1789.  None of them have a plug!  I ran a stiff wire in the hole all the way to the far side of the case and nothing.  Engine 1490 was apart when I got it and 100 has been hot tanked and ultrasonically cleaned so maybe the plugs fell out.  I just tore down 1789, which didn't show any evidence of previous disassembly and haven't had a chance to clean up the cases yet so I don't think a plug fell out of that one.  When I worked on engines 5491 and 12029 I don't recall seeing a plug and neither one is leaking.  I wonder what the odds are that I happen to lose at least 3 plugs without realiziing it.  Cliff, I wish I would have seen your post about the flat spot on one side before I checked out my cases.  I'm pretty sure all of mine are round but I wasn't really looking for that but I'll go back and check.  In your first post did you say that it looked like the hole was threaded?

[josephus]

I have had the same problem with losing the plug . My solution was put a properly sized O ring in and put the cover on. the cover compresses the O ring and stops the leak. as for the bolts going thru the side cover and into the engine case i clean the threaded holes and bolts and put some nail polish on them . my side plate stays dry as a bone.

[Magpie]

Mark, no I can't see any threads in there. My concern about putting a plug in is the depth of the plug so it doesn't block the oil flow to the trans. It may be that there never was a plug there in the first place. That would be an easy thing to lose during a tear down. It seems strange that an important oil gallery would end just like that and that it is plugged on a later model with an edge on the plug so it will not go in further. It may be one of those thousands of upgrades they did as they went along with production.
Am I chasing a ghost? and getting everyone wound up for no reason? If that's the case I'll go put on a pointy hat on and stand in the corner for awhile.
Cliff.

[MRieck]

This has really got me scratching my head.     I happen to have 3 sandcast cases apart that I looked at, 100, 1490 and 1789.  None of them have a plug!  I ran a stiff wire in the hole all the way to the far side of the case and nothing.  Engine 1490 was apart when I got it and 100 has been hot tanked and ultrasonically cleaned so maybe the plugs fell out.  I just tore down 1789, which didn't show any evidence of previous disassembly and haven't had a chance to clean up the cases yet so I don't think a plug fell out of that one.  When I worked on engines 5491 and 12029 I don't recall seeing a plug and neither one is leaking. I wonder what the odds are that I happen to lose at least 3 plugs without realiziing it.  Cliff, I wish I would have seen your post about the flat spot on one side before I checked out my cases.  I'm pretty sure all of mine are round but I wasn't really looking for that but I'll go back and check.  In your first post did you say that it looked like the hole was threaded?

  Very, very slim. It appears they did not come on the first bikes. I retract my earlier statement. That being said I would still plug it if possible.