Oil filter bolt & cover modifications? and oil flow clarification.

Hey folks,
I'm currently working on a revival of a customised '81(ish) 750E build and was at the stage of replacing the oil filter, when I immediately noticed something was different with this motor.

The filter bolt had a large spacer "welded" onto it. The boogers were so thick that I could hardly get a socket on securely, so I spent a few minutes filing down the hastily placed beads.
 

Whilst getting close and personal with the file, I couldn't help but notice the mismatched bolts around the perimeter of the cover.
 

Alarm bells start ringing, but ultimately, this is what was extracted.
There was a filter installed, at least (this is just a NOS filter that I had floating around in my decades worth of spare parts).
 

There was a washer, but no spring, and obviously there was a fence.
 

Bolt and cover, with all other components removed.
 

And, of course, the internal shot.
I feel the next set of photos may need to be tagged as "NSFW", but you have made it this far, so:
 
 


My questions regarding what you have just witnessed:

1. What disaster could have occurred to necessitate the need for these "repairs"?
2. In a standard filter setup, what is the function of the spring (that sits between the washer and the fence)?
   and a question somewhat related: does the filter move up and down on the bolt during normal operation (aided by the spring)?
3. What would you do upon discovering this situation?

Thanks in advance.
I am a long time lurker, first time poster, and will definitely be posting a build thread of this bike shortly.




 

I believe the answer to question 1 regarding the last two photos is this: the threads for the filter bolt (at the top of the chamber) were ruined and the repair was to bore the hole larger then weld an alumum plug in and tap the threads for the bolt.  Nothing wrong with that method if done correctly.  But the ham fisted grinding of the welds afterwards scares me, and may explain why such awful work had to be done on the cover and bolt head.  I feel a reputable machinist would do the bore, weld, tapping repair and no other changes would be required, since he could machine the welds flush with an end mill and retain the original chamber height using the same set up as the tapping operation.  Kind of a coincidence here - my machinist and I have discussed the same repair for one of my motors, as the threads for my filter bolt are getting worn and loose, and we don't know if we can find the right size heli-coil.

The 2 pics below show what things should look like. Everything held in by the big bolt. I wonder if your cover was home made. The cup (?) In the pic has holes. Some did some didn't and I don't know why. I just assumed the spring - not in pic - was to compensate for possible variation in filters.  

What could have caused this ? Accident ? Big hammer ? Buggered oil pan and filter cover? Bolt banged out?

Good luck

As for the cause I think I have seen a sheared off oil filter bolt thread on a 750 case before. It may even be documented on here (use search function)

It was a member on here called "zukdave" and I believe it happened to his 650 drag bike when the hex got snagged on the lip of a trailer ramp on a hard push. A big hit to the hex transfers up to the threaded portion of the case which rips that threaded portion out. 

Zukdave usually only posted in the "racing" section.

Its probably a weak spot in those casting, possible venting issue causing porosity (air bubbles) in the molten aluminum. This is a freak incident, something that in normal use would never be a issue.

It also looks like the PO fabricated that oil filter cover from billet.

Having a drag bike with a low oil sump (diy extended tube) I am always cautious/worried when pushing it up onto trailer ramps, especially those made out of "expanded" metal where the hex can "snag".
 

I do remember the post as well Alex. Not sure if here on KZR or on the old kz650.info site. Have not done a search here to see which. 

Thanks for the answers so far.

The cover plate actually has a thread tapped into the center hole, and appears to have been "faced" to provide clearance. There is also an extra rubber seal on the bolt.

I'll be digging out a stock filter bolt & cover, and will update with pics to show how far out the stock parts fit.

ChopperAddict post=918987 userid=65385Thanks for the answers so far.

The cover plate actually has a thread tapped into the center hole, and appears to have been "faced" to provide clearance. There is also an extra rubber seal on the bolt.

I'll be digging out a stock filter bolt & cover, and will update with pics to show how far out the stock parts fit.

One potential issue I see with using the stock parts is the PO has drilled and tapped the oil pan gasket surface for those mounting bolts on that diy cover plate. Those bolts holes are on the sealing surface of the stock filter covers O ring, this is a potential leak area.

I can see in the pictures where the guy used Loctite purple gasket maker to seal that bolt hole surface. I bet that probably leaked oil

You could fill the threaded holes up with high heat RTV or JB Weld, but it would be hard to say if that would seal or not. The other solution would be to replace the oil pan with a used stock one.
 

wrote:

I feel a reputable machinist would do the bore, weld, tapping repair and no other changes would be required, since he could machine the welds flush with an end mill and retain the original chamber height using the same set up as the tapping operation.  Kind of a coincidence here - my machinist and I have discussed the same repair for one of my motors, as the threads for my filter bolt are getting worn and loose, and we don't know if we can find the right size heli-coil.
 

For a thread like that I believe the solution would be to make your own threaded weld bung from 6061 and have it tig welded in. Design the weld bung so it sticks up inside the case so it can be welded on the back side with the oil pan and filter bolt assembled so it lines up perfectly. Then disassemble to complete welding from the filter side, and mill flush on both sides of the bottom case as required.