KZ305 Rebuild...attempt

I have no spec to check. I went through every page that mentions pistons and piston rings in my manual.

The ring end gap is listed on page 129 of the factory service manual.

Look for a table that has engine wear specs, do you have a pdf file you can share?
I looked up the installed ring  gap for a 1000 and it is  0.30  - 0.50 mm
I also looked up the 550 manual and found the engine wear table on page  121  it listed the installed ring gap at  0.20 - 0.70 mm on the top of page 122
The pistons for a 550 are pretty close to yours size wise  I think, so if you are around 0.40 or 0.50mm that should be about right  WRONG INFORMATION !  
A lot of this spec stuff is common to other bikes and you may find a lot of good info on pistons in the 550 manual even if it is a bad copy  
filebase (kzrider.com)  

wrote:

Look for a table that has engine wear specs, do you have a pdf file you can share?
I looked up the installed ring  gap for a 1000 and it is  0.30  - 0.50 mm
I also looked up the 550 manual and found the engine wear table on page  121  it listed the installed ring gap at  0.20 - 0.70 mm on the top of page 122
The pistons for a 550 are pretty close to yours size wise  I think, so if you are around 0.40 or 0.50mm that should be about right
A lot of this spec stuff is common to other bikes and you may find a lot of good info on pistons in the 550 manual even if it is a bad copy

 
filebase (kzrider.

Those gaps are too big. The post above is from the fsm for the 305.

I stand corrected , that is some tight tolerances 

Well Hot damn, there it is! Now post the index listings for "pistons" and "piston rings" from the manual, because they list a lot of pages for both but neither of them list page 129!  I hate this friggin manual, in order to do anything you have to jump from page to page to page, and many of the index entries direct you to a page that just redirects you another page!! It leaves a lot to be desired.

Well under the weight of all this pressure I have no choice but to try and gap them now, but if I somehow mange to succeed without breaking any more I'm inclined to proceed with the old top ring from my good piston on that piston. I've already dumped enough money into this thing and I just cant swallow paying $50 bucks for one freakin ring. Don't do it, it may ruin my bike, you say. Well there was a pretty good chance I was going to ruin it somehow anyway.

 

wrote:

if I somehow mange to succeed without breaking any more I'm inclined to proceed with the old top ring from my good piston on that piston. I've already dumped enough money into this thing and I just cant swallow paying $50 bucks for one freakin ring. Don't do it, it may ruin my bike, you say. Well there was a pretty good chance I was going to ruin it somehow anyway.

 

There's one thing I try to keep in mind: don't let the perfect be the enemy of the good.

Would it be ideal (or perfect) to have brand new rings? Sure. Is there anything serious, or even minor, wrong with the old ring? Doesn't sound like that's the case. It might not be the best option ever to re-use the old ring, but it's arguably better than stopping the project completely for lack of a new ring. The old ring is probably 80% as good as a new one; that's a B-.

The outer surface of the used ring where it meets the bore looks fine (I  have a microscope), and it came off the good piston that didn't show any issues. It would go back on that same piston which will go into the same bore. There are some signs of wear, light scratching of the chrome, on the upper/lower surfaces but I don't expect they would interfere with its function.

Due to the situation with the scored cylinder and the difficulty/expense of finding parts for 305s I'm looking at this whole project as a temporary fix until I find another bike. That's why I'm not keen on throwing more money at it to make things "perfect". I would hope it gets me through this year and maybe next year, but I will be looking long and hard at finding another bike with easier to find parts because to be honest I'll be surprised if this one makes it through 2 more seasons.
 

Fortunately the seller of my aftermarket rings is going to replace them free of charge. I busted another one taking it off by hand, so I can't win. Gonna take the new set to the Harley guy and have him put em on. Maybe I can teach him some simple conversions for the mysterious measure known as millimeters at that time.

 

OK, back on track. Had my Harley guy gap and install my rings so I don't do anything stupid again, and ordered some carb diaphragms from JBM because it looks like even I can can install those without breaking anything. Haha. I hope.

One question I have looking forward is how do I know if the cam chain is engaged properly in the crankcase when I go to put it back on the camshaft sprocket? I have prevented it from falling into the crankcase with a wire but I haven't kept it under tension the whole time so I presume it could have slipped off down below...

You should be able to tell if it's on the crank sprocket - it'll be straight and won't move. If it's on the crank at an angle you'll know. Be sure your cam chain tensioner is off when you're putting the camshaft back in.

Getting the timing right can be a bit of a struggle though.