Topic: Unexpected Project

[MHansen105]

Hey y'all,

I need some opinions, I'm pretty sure I'll get one here!

If at all possible, I need some options, but I'm not hopefull about that.

Short story is, I bought a '78 CB750K as a runner.  In order to transfer the title from Virginia to Texas it needs an inspection.  Just before going down for the inspection, I thought I'd change the oil and filter.  When the oil filter cover came off, this is what I found. 




I can only assume that the missing metal went through the engine at some point, and I'll have to strip the thing down and replace/refurbish most of the components.  I was expecting to do that, just not quite so soon.

So, my question is, does this mean a new lower crankcase half, or is there some way to repair this?

Any help/advice is appreciated.

Monte

"I've always been crazy, but it's kept me from going insane."  Waylon Jennings.

[Frankencake]

That looks like hammer poisoning!

The only way to fix that would to be to weld and machine.  It would require splitting the case. 
The damage is already done internally.  Run it, but stay close to home.  I'd be looking for a new used engine if I was ya'll.

[MHansen105]

That looks like hammer poisoning!

The only way to fix that would to be to weld and machine.  It would require splitting the case. 
The damage is already done internally.  Run it, but stay close to home.  I'd be looking for a new used engine if I was ya'll.

Cupcake,

I'm thinking someone over torqued the filter bolt at some point.  I wasn't able to get the filter and cover back on, but that was when the exhaust wast still on.  I may try it again now that the pipes are out of the way.

Your advice is sound, stay close to home indeed!  And yes, I'm already looking for a replacement engine.

Thanks

Monte

[bwaller]

And maybe get a longer engine mount bolt. 

[MHansen105]

And maybe get a longer engine mount bolt. 

Bwaller,

Good eye!

I noticed that the bracket on that side is welded on, while the bracket on the other side is bolted on.  It must be a repair from a PO.

I want to make this a rider, but stay pretty origional, so I guess I can live with the weld and the extra long bolt. 

[fastbroshi]

  I'd pull the sump and check the pan for bits, then check the screen.  Then maybe R & I the pump.  Unless you can get a hold of the PO to question them about it and they give you reason not to.

[Jerry Rxman Griffin aka MuthaF'er]

I don't think you'll find any big chunks because the guy in Virginia has already removed them when he broke it. You're probably fine as long as the screen on the oil pump is good. Wouldn't hurt to remove the oil pan and clean out the sump though.

[MasterChief750]

mounts on the left side of the bike should be welded to the frame. the ones on the right are removable to ease insertion/removal of the motor.

[mec]

running this engine means that you will loose the function of the oil filter element.

as mentiones above -> TIG welding and machining

i suggest however a complete dissasembling of the engine to clean all oil passages.

mec

[Frankencake]

running this engine means that you will loose the function of the oil filter element.

as mentiones above -> TIG welding and machining

i suggest however a complete dissasembling of the engine to clean all oil passages.

mec

Exactly, which is why I said that the damage is already done.  It would be simpler to get a junker and swap it out.  Rebuilding this motor/case could be done but why?  There's no shortage of motors for these bikes so far.  (until one of us collects them all)

[MHansen105]

Thanks for all the responses guys.

I must say that your responses have been much more polite than some forums I've been to!

Good information on the difference between the left and right motor mount points.  As you may have guessed this is my first experience with a CB750.

I think I will try to get the oil filter and cover back on and ride it locally for awhile, while looking for that alternate engine.  Finding that engine seemed like an easy task to me too, until last week.  I've been looking for one, but no luck yet.

On that note, y'all can probably let me know if there are any CB750 engines that won't work in a '78 frame?

Thanks in advace,

Monte
 

[MHansen105]

Hey Guys,

I put the new oil filter on, started her up and she did develop oil pressure.  If no oil leaks develop overnight, she'll go for an inspection in the next week or so.

Thanks for your help.  I'm still looking for an engine.

Monte

[Frankencake]

What part of the country are you from?  I know of a place that has what you need in Central NY.

You will get oil pressure with that wound.  The oil just won't navigate it self through the filter element. 

This is a great opportunity to see just how long one of these engines will run without oil filtration.  I'll expect a full report on my desk.

In theory, you could accomplish filtering by putting an inline filter on the hose exiting the tank.  Find a remote filter mount like those that are used in marine applications and use a spin on filter.

[MHansen105]

Cupcake Hunter,

I'm in San Antonio TX, kind of a long way from NY!

The oil filter in the oil line and/or the spin-on oil filter were some of the ideas that I had in mind.  I've heard about a conversion kit for a spin-on filter, but haven't found a description of one yet.

I'll try to keep everyone informed of the progress on this bike.  I will be doing a full tear-down, inspection an rebuild at some time, probably pretty soon.

Monte