New Engine after 18,000 miles

[sidthesloth]

Yes, in each ring groove there is a locating pin, the ring gaps line up with it and it prevents the ring from rotating on the piston during service. If you filed enough off the ring ends you would then have to file that notch back, with a littld care and patience all will be fine. I think it would be unusal to need to do this though, the rings should be within tolerance.

[rigpa]

i'm looking online for replacement rings, etc. is the cylinder aluminum, and is it horizontal.  will any rings for a 39mm piston work?

[sidthesloth]

No, the zx has a vertical, cast iron cylinder. I think it would be best to get piston and rings as a set.

[thebatman]

a local kymco/kawasaki shop keeps them in stock for around $32.00..i believe thats what it was after taxes..for me, oem parts are easier there at dal-kawa......stadiumyamaha.com has alot of oem kymco parts..either site should be all you need..dont sweat the gaps, they are ready from the factory(i guess you have the one in a mill shot of getting a bad part tho)..

[rigpa]

i checked in with stadium.  they said their rings don't come with instructions.  is there a certain side that goes up/down.  will it matter which ring i put on which groove and if so how will i know?  check against the ones already on?

[thebatman]

yeah the rings are marked when you take them out of the box....a T for the top, a B for the bottom. put the letter facing up. its a small letter of course. the rings can only go in "thier" slot on the zx. you can see the difference when you have the piston open where you can see it.

[Hoolander2]

If one actually needed to file the ends of the rings, one should never file the notched area since that already fits the piston perfectly.  Just the part that juts out beyond the notch.  Again, in your situation, it'd be almost impossible you'd have to do that. 

Did you do your compression check?

[rigpa]

I apologize I have not done the compression test yet.  Too exhausted from painting the house and pulling weeds, but i have run 3 tanks of gas with some sea foam and it's made a good difference.  I will do it soon.  Meanwhile all the discussion about the piston and it's rings has been enormously helpful.

[thebatman]

we gotta help each other..    everybody wants to ride and go fast

[sidthesloth]

The first time you do a job like that, (replacing piston/rings), it can be daunting, but once you have done it you see it is not that dificult. I have had mine apart so many times now, I have lost count.
A recent job I had on my car was to remove the complete instrument panel, a very scary proposition, but I couldn't afford to have the dealer do it so I set to and got the job done. I guess what I am trying to say is have a go.

[rigpa]

so, i tried to hook up the compression gage to the spark plug cylinder hole last night, and there simply wasn't enough room to get the gage in the hole.  what else do i have to remove.  i removed the seat, and side panel, but it looks like i might have to take the muffler and cylinder cover off?  i've changed the spark plug plenty of times, but as you know, there's not much wiggle room on the zx 50.

[Hoolander2]

Not familiar with it.   Come on ZX guys. 

[art]

  Try removing the nut at the bottem of the shock mount. Than lift the frame of the bike from the back. This should give you a bit more room.
  Alot of compression guages have  a flex hose may need another type of fitting if this don't work.

[thebatman]

it is very tight in there, but the ones i have used, do work, just have to play and twist whole thing holding the gage it self...you may be able to let the air out of rear tire to get a bit of room....... guess you could lossen the inner fender/oil tank to give extra room..hope this helps...

[Hoolander2]

So, Art, you saying take off both bottom rear shock mounts so the swing arm/engine will point more up?  Sounds reasonable.  Then would you just leave scoot on center stand and let wheel drop to the ground?