Hole blown through crankcase

New to the site and Kawasaki fours. Saying that, I've had experience with different types of engines.

This is really reaching, but if there were casting flaws in the engine cases, the excess pressure inside could have pushed those pieces out. I don't think that's what happened though.

When you have a failure like this, you almost have to disassemble the engine to find out what happened. Something turned loose inside the cases and blew those holes out. It doesn't always have to be a connecting rod or part of the rotating assembly.

You say the engine can be started and it runs with no noise right ? I'd say you lost a rod nut. The rod could still hang on with one nut left. The high RPM of these engines could have bounced the nut around several times. It would only take one rod nut to knock out the two places in your cases.

Your cases are toast. Those holes are too big to fill in with JB WELD. If you had the chunks that came out of the cases, you might be able to get away with it. You'll be better off scoring a used engine, cases, or another bike .

Wrong area for hydrolock damage-would be looking more for a chunk of metal/nut/bolt/part of the cam chain guide coming loose and exiting the case. Seeing that makes me remember getting the willies looking at a buddies z1rtc back in the day. Turbo under the seat spinning-say-25000 rpm-what could possibly happen if that thing grenades?

jumpship wrote: en.m.wikipedia.org/wiki/Hydrolock just what he mentioned. This is it 100%. The bike wouldn't turn over sometimes I wondered when attempting to start. So basically the new racing carbs and me leaving the bike on prime caused gas to go into the engine or just too much oil or both caused this

Hydrolock happens when the cylinder has fluid in it and when the piston rises it cannot compress the fluid so damage happens to the piston; rod; or head. The fact that your engine still runs ok indicates no damage was done to the rods, etc.; so it appears your engine did not suffer hydrolock. In any case, those holes in the front of the engine case would not have been caused by hydrolock.

I would pull the oil pan and see if there are any clues to be found there. You may find nuts, bolts, or chunks of this or that in there. Ed

Hmm that's not overpreasure (think of how your crankcase would look if you tried to blow it up like a balloon, you would see bulging on every straight surface, and the weakest point would have blown, that area of the block is not a weak spot.

Hydrolock is almost unheard of in a aircooled street engine.
(besides those dumbasses who tries to use the engine as a submarine crossing rivers and such)¨
hydrolock occurs between the head and the piston.
most commonly it happens in nitro engines, (dragsters) because they pump so much fuel into the engine so it will only take a few cycles whitout combustion to bring the liquid content up to the point where it is no longer compressible.
btw your case is repairable but I would replace it since it will involves to much work IMHO.
Welding or soldering is the only way I see, and since it is so close to a sealing area it would require machining later.
no just get a new case.

But now you have peaked my interest, find out what caused this, take loads of pictures.

I put my money on a connecting rod bolt failure.
Now go out there and pull the pan take a good amount of pictures and the mystery will be solved.
Seriously if you had been living in Sweden and somewhat near here I would do it for you free of charge just because now I HAVE to know what happened .
best regards H

I'm with KZ rat on this one. Something went through the cam chain/cam chain tensioner.

Let us know ASAP!

Alright guys, looks like all i need is some jb-weld!!!

im gonna humble myself, This was my first ever experience with a blown engine like this so A LOT was going through my head as you guys can see. Looks like the truth of the matter is :
1.Rod was bent first, and than the piston snapped off from the pressure, and the rod itself smashed its way through the case and the rod is now stuck against the crankshaft as seen in the picture. How the heck could this have happened? Engine had 20k miles on it....

I still dont know extactly what caused this, CR Special carbs too lean? Why would only one piston blow up and the rest look totally fine. I really think it was because left the fuel cock on PRIME and left it on its side stand and these kz's lean over way hard. So im thinking it was hydrolocking in that one piston and couldnt really fire and when i really got on the gas is when the rod firstly bent and then snapped the piston off.

Once again i'd like to mention that the bike at one point DID hydrolock when i left the fuel on the motor wouldnt turn, it was locked. i had to use some persuasion to start it and the very day i left work i left the fuel on again....................... www.zggtr.org/index.php?topic=1209.0 , and www.cbxworld.com/features/hydrolock/hydrolock.htm are both some sources that back up what im saying. Guys agree with me?

jumpship wrote: ...What narrows a lot of this down is that the bike starts and still runs strong. ....

jumpship wrote: ...She starts/runs on all 4 cylinders....

:huh:

Good Fortune!

Patton wrote:

jumpship wrote: ...What narrows a lot of this down is that the bike starts and still runs strong. ....

jumpship wrote: ...She starts/runs on all 4 cylinders....

:huh:

Good Fortune!

+1 !
jumpship wrote:
"The bike fires right up with no abnormal clunking or anything, in fact it sounds exactly the same, firing on all 4 and sounds real strong and good actually, If the bike was running too lean and popped the engine i don't think it would still be able run like it is able to now..."

I find it remarkable that the engine still ran strong on all 4 cylinders and had no abnormal clunking or anything with a broken piston and a bent rod stuck against the crankcase. :blink: Ed

I know man, I was in the moment and wasn't thinking straight... but there weren't any clunks because I think the rod was just spinning with the crankshaft and it already smashed through the case so there's nothing else to hit! Lol!! So how do u think this happened? I really don't want this to happen again when I build the engine back again

Could be the previous hydrolocking episode bent the rod, which eventually caused the rod bearing to lock up and seize. Piston seizing from running too lean is not unheard of too. What does the other side of the piston look like?

Ouch! Time for a donor motor. Could be worse- could be the owner of this $20k piece of scrap metal!

The top of the piston is caked with carbon? And honestly it looks a little wet/damp around the edges... I have the 810 kit from a friend, now I heard milling the head increases compression but will I need to do anything if I shave the head or can I just throw everything back together the way it was