Topic: Stopper, bottom 11204-300-010 CB750 K0-K2 ? Important part?

[PeWe]

Anyone that know what this part is for?

I saw a part shown on the case chart "stopper bottom 11204-300-010". Only for CB750 K0, K1 and K2 engines.
Where should it be mounted? The chart does not show exactly where.

I have a K2 crank case I intend to assemble to a complete spare engine. I have found this part, NOS for 5€.
http://images.cmsnl.com/img/products/stopperbottom_big11204300010-01_2136.jpg

[ekpent]

 I goggled the part number and it showed on a Partzilla schematic. Says its used up to serial number 74117. Shows it by the bottom of the crankcase. The shape of the part looks different than what you posted. Still not sure what the heck it is though. See if this link works, seem the schematics never come through or google the number and check Partzilla. Part #2 matches your number, bracket for nuetral switch ??   http://www.partzilla.com/parts/search/Honda/Motorcycle/Models%20with%20no%20year/CB750K1%20A/CRANKCASE/parts.html

[PeWe]

CMSNL K2 say: from serial number: 1007415
It does not specify if it is inside or outside of the case. can be inside since pos 10 is inside (Oil Guide,final)
http://www.cmsnl.com/honda-cb750k2-four-general-export_model14368/partslist/E22.html#results

Some parts look like a part of the case but can be removed. It would be nice to know what this is for

[Kevin D]

There is a round plug on the bottom case near the trans, a couple inches diameter. Just a guess, I think they used the hole to make sure the shift forks were engaged properly after mating the cases. Anyway, there is a triangular extension on the oil pan to hold the plug on one side, and this clip holds it on the other, outside. A picture of the bottom case will prove it. Or just get the inspection mirror and look under the motor near the tranny. I think Terry told me there is an Oring on the round plug, but it's not spec'd on any diagram.

[Kevin D]

Found the picture, 9 years ago.

[HondaMan]

I have only seen those a few times. They didn't appear to be needed? The plug stays in OK by itself.

[kmb69]

..... The plug stays in OK by itself.

Not exactly. The oil pan holds it in sans the stopper.

[ekpent]

Looks like mystery solved. Will have to crawl under some of my early bikes sometime now to take a peek, never noticed that.

[PeWe]

Kevin D,
Thank you very much for the explanation!

[Kevin D]

PeWe , in trying to make my engine leak free, I asked about the plug, but decided to leave it be. I tried to push it out by hand, but no go, and I didn't want to start beating on it. I'm guessing again now, that both the case and plug are grooved for an oring.
 I'm 9 years 20kmiles? since the teardown and the engine isn't bone dry but it is pretty good.☺

[PeWe]

My K6 has no extra keeping it in place except for the oil pan cover tab. Case casting has no ridge for thread. see photo

I noticed that my K2 block was casted for the bolt keeping the stopper, but its grinded off. (A round plug) The cut look fresh with sharp burrs that can have been done the last 20 years OR from Honda if not touched afterwards. I guess a vandal has cut it.
Serialnumber of the block is within the K2 range. CB750E-202754x

Removal plug might be good for inspection. I'm convinced that this kind of plug should be left alone to avoid leak.
EDIT K2 blocks added. No thread for stopper

[HondaMan]

A few years ago, someone here posted a question about how to put this plug back in: he had removed it during his total teardown and was trying to find an O-ring big enough to fit onto it, and was trying to discover a way to re-press it back into the hole. I never heard how it ended?

On the 4 engines I have here right now, none of the "tabs" on the oil pans actually touch this plug. I think those are there in case it ever starts to come loose? It appears to have been the tool-holding point for the cases while they were being machined: a ground-flat surface with a located hole, clamped on a large dowel to fixture it into the NC machine(s) that drilled and milled on it. In those days we only had the old punch-tape NC (Numerically Coded) "automatic" machining centers, so making the case sit EXACTLY in place was required to make it all work: they could not just "re-reference the zero" with a computer touch and go from there. Honda was a leader in implementing this tech in those days, with Okuma doing many of their lathes and Mitsumi and Mitsubishi making their machining centers, some of which are visible in the old pictures we see now and then.