KZ305 Rebuild...attempt

So ahh, looking forward to the next thing I'm going to screw up, do I need to gap the rings somehow? I don't see anything in the manual about that. Reason I ask is the 2nd ring on both pistons (and these are aftermarket rings) are definitely sitting proud of the top ring. Being my first and hopefully last rebuild, maybe that's normal but it doesn't look right. And yes I've got them on in the proper order and orientation.

What do you mean by "sitting proud"?  A photo would be useful.

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What do you mean by "sitting proud"?  A photo would be useful.

 

I just mean they are sticking out farther than the top rings. I'm wondering if they stretched a bit when I installed them. It may be nothing to worry about but having never done this before I will worry about every little thing.

The first and second ring are not identical on this bike, FWIW.

The first (top) ring





The 2nd ring. Both pics taken with the respective ring pushed all the way toward their end gaps. It may look worse than it is, its in no danger of coming out and once its in the bore it certainly won't come out. But it is sticking out more. Not sure there's anything to be done, if I took em off and gapped them tighter they'd probably end up the same when I put em back on.
 

The ring sitting out like that is not a problem per say, but you need to set the end gap of course.  The factory manual should have the specs.  Basically, you need to remove the ring from the piston and squeeze it together and put it down into the bore a small distance, making sure it's evenly installed, then use a feeler gauge to check the distance between the ends.  If too tight file to fit the spec.  Something in the range of .015" (just a guess.)  Only after the gaps are set should the rings go onto the pistons.  You will want some sort of ring compressors before attempting to stick those rings/pistons into the cylinder.  And make care the oil ring expander is not overlapping.  Improperly installed, or broken rings during install, are quite common so don't fall into that trap.

It looks like it was stretched.  Follow Nessism's instructions.  Be careful.  They are made of high strength material and snap easily.

Like I said, I find nothing in the manual about gapping them or I would have gapped them.  There is no spec. to check.

And no need to warn me about the fragility of these things. After I was concerned that I may have stretched the 2nd rings installing them by hand I decided to use ring pliers to install the top rings and SNAP. Broke one of them. Now I have to buy 2 whole new fucking sets of aftermarket rings (or pay even more for 1 set of NOS) or reuse the old one, neither of which is desirable.

Sorry to hear that you need more rings.  We've all broken them during installation so welcome to the club.  

Interesting that there is no gap spec in your manual.  What diameter is the piston?  If the same diameter as a Z1 then you can use the spec in the Z1 manual as a guide.

You need to be real bad to snap those rings. Cast iron rings on were totally different story. You sneeze at those - they break

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You need to be real bad to snap those rings. Cast iron rings on were totally different story. You sneeze at those - they break



 

Well you must have missed the head gasket thread previous to this one and the first sentence of this thread where I said "I'm gonna go ahead and give this a whirl, despite being unqualified for the job".
 
The only reason I undertook this is because it was either that or junk the bike, even though I knew I would likely end up with junk anyway. But I wasn't going to pay 2-3K to have someone else rebuild a $300 bike.

Anyway it wouldn't have broken if I hadn't used the ring pliers. I had the top rings on and off a couple times by hand without breaking them. The question is whether I stretched the 2nd rings, which seem stiffer, and what if anything I should do about it. I'm perfectly capable of stretching them again, if indeed I have.



 

Luckily for you, I spent today tearing mine down to replace the crankcase that I messed up. The second ring on both of my pistons sticks out more, so I wouldn't worry about yours...though I would gap the new ones and be sure to debur them. 

I'm also pleased to note that you don't need a piston ring compressor to install the cylinders - the bottoms are flared, they just slide on. Phew. 


 

I installed a ring in a cylinder and pushed the piston up to level the ring and then checked the gap with feeler gauges, thankfully they all were with in specs.