KZP engine rebuild

If there's oil in the cracks, it will contaminate the welds.
Steve

swest wrote: If there's oil in the cracks, it will contaminate the welds.
Steve

I'm with you Steve. I can see the inside of the case now and the crack does not look too bad. Might be worse under all that JB Weld.

Remove all JBWeld to see the crack you have to deal with.
Sand aluminum around crack (sandpaper #20 or 40), degrease, then apply JBWeld with fiberglass patch.

I have cylinder block and pistons from 81 KZ1000. Pistons and block +1mm.
Block has to be bored for next size pistons

When I did my swing arm mod, jeff had me grind the edges deep so he could fill them in. That's what I suggest you do. A thin cutoff wheel should do it.
Steve

Ok. The jugs are at the machinist's getting cleaned and measured.
I was able to get the engine out and turned upside down so I could get a better look at the "problem area".

I was prepared to start grinding away to get this stuff off. Even had my torch ready... No Need. This crap just popped off with a screw driver.

I was done in less than a minute.
Here is what we are dealing with:

The next step is to put it in the back of my son's CJ and haul it down to the welder.

If that were mine I would junk that case. The two outer bolts at the #7 and #8 you see are the main bearing cap bolts. I see what looks like cracks in that area. My second choice would be to weld it up if possible. There is NO WAY I would reuse that case on a bike I was going to keep.

If it were me, I'd grind and see how far they go. A good welder can fill and beef up the areas that might be weak. Doesn't look shattered to me.
Steve

Welding it up is a great option however I usually look at the cost. I can get a complete good case for under $100.00, I've bought complete engines for that, welding it correctly will cost more than that.

I have seen a few cases on eBay but they are $180-200. Plus you have to factor in all new seals and other incidentals.
I am going to take it to my machinist. I've used him forever and would trust his judgment on this. If he says the cost to weld is too high, then I'll look into getting another set of cases. I send him a lot of business so I hope he'll take it easy on me...
I'll let you all know how it goes...

Welder will spend 30 min grinding cracks and 5 min welding. Get instructions from your welder and grind yourself. You will still have to use JBWeld, weld line can have very small holes.

Any updates?
Steve