Minimal tests before reassembly?

I had plans to get my case checked over, crank welded, maybe even balanced. Alas, plans change. My local engine shop which has given great service over the past three decades has closed its doors, and my bank account suggests that I should probably just try to put this engine back together and only fix actual problems.

So here's the deal.. I have a 1981 KZ1000J engine with a broken bottom case. I have a replacement case from a 1981 police bike (including the center crank piece) that appears to be in great shape, but it WAS shipped through the mail. The only precision devices I have available are some digital calipers and a dial gauge. There are no obvious wear marks on either case although I haven't checked the bearings yet, and surprisingly little debris in the pan of the original case. I only wish the car engines I have worked on had looked so clean! The original engine has around 18k miles. The case is broken due to the intermediate starter gear busting its center pin, I'm guessing from bad timing and a kick-back while trying to start?

What would be the minimum that I should look for before putting everything back together in the new case? This is just going to be a daily street bike, I'm not expecting anything crazy. I know the engine was still running when sold (PO pulled it behind a truck to get it started). I also plan on honing the cylinder walls and lapping the valves. What else should I be looking for?

Thanks for the help.

If it's stock, put it together.
Steve

That's kinda what I was thinking. There's definite glazing of the cylinder walls, but honing is easy. There's also signs that one valve is leaking, thus the desire the lapp them. But otherwise my only real concern is whether the new case might have gotten twisted during shipping -- however there was no damage to the box and no obvious marks to indicate the case may have been dropped on a corner, so my concern for this is pretty minimal. I might try to measure ring gap if my book has the specs. The new case has been completely cleaned and I have a new set of gaskets, so I'm thinking it should go back together pretty smoothly.

My hesitation is because this is my first motorcycle engine. I can apply some knowledge from car engines to this, but I have no idea what to look for around the transmission gears, and of course a motorcycle engine will likely have different areas to look for wear, and I've never seen bearings like this before.

Pics will help. New valve guide seals and rings. Maybe valves and seat grind depending what you find.
Steve
kzrider.com/forum/2-engine/596420-valves

Pics of anything specific? I can take some of the inside of the cases when I get home.

Regarding the valve leak, note the cam at the top-left. That brownish haze wasn't present on any other lobe.

I wasn't clear if you had both replacement upper and lower cases that are a matched set. They are machined together at the factory and cannot be swapped. Also if using the old crank you'll need to take care of bearing selection by measuring to determine if different bearing sizes are needed. R

I'm probably screwing up the terminology... I do have both halves of what I'm calling the 'lower' case... Basically the top and bottom half of the area that the crank and gearbox sit in, plus the piece the holds the center of the crank. My understanding was that I could then bolt on any cylinder housing and top piece with the cams.

Other than visual scuffing, are there any indicators for NOT re-using the old bearings?

Sorry I haven't had a chance to get any more pics posted. I introduced a teenager to the front of my truck last week and spent all day Friday getting work done on the front end. Still found a bad ball joint yesterday (that I had just replaced about 5000 miles ago), so probably taking the truck back in again tomorrow. That'll probably make the *third* alignment done this week.

Ok so you have both case halves, good you cannot mix case halves without machining. If you do not have a Kaw manual, get one, it is very helpful. The book for my model has bearing pictures, inspection and measurement procedures involved with splitting the cases and reassembly. For my model there are crank and bearing markings/colors that correspond with bearing selection. If you have the right pieces and they are not obvioulsy worn/burnt/broken then you are good to go. I would check it tho as you are apparently using your old crank with new cases. Good luck. R