New Engine after 18,000 miles

[rigpa]

here are the cylinder striations.

[rigpa]

so what do ya'll think?  are they goners?  i sanded the piston ring a bit, but i can still feel the grooves. 

[Hoolander2]

Yeah, if you can feel those gouges it's probably best to get all new.  They look pretty deep. 

Before you run the rebuilt top end, check your oil injection system top to bottom.  Make sure no blockages or leaks in the lines, tank, ect.  No old goopy gunk in the lines/tank. 

Too bad -- we were all hoping it'd be less serious.   

[sidthesloth]

Yes, I think it would be worth getting all new if you can. If you look around, you can find replacement kits for a reasonable price. I am not sure, but I think I saw $60 kits on ebay when I was looking for an upgrade kit for my scoot. Good luck.

[wordslinger]

so what do ya'll think?  are they goners?


..oh yeah...they're gone.....

[sidthesloth]

Here is a link to a replacement kit on ebay.
http://cgi.ebay.com/ebaymotors/Honda-DIO-50cc-replacement-cylinder-kit-_W0QQcmdZViewItemQQhashZitem35aca8373aQQitemZ230529972026QQptZMotorcyclesQ5fPartsQ5fAccessories

It is advertised as Honda Dio, which is what the kymco ZX50 is a clone of.
Did you end up getting your piston kit?

[rigpa]

sidthesloth, you have totally outdone yourself.  i'm not seeing the sloth in sid.  the ebay kit is AWESOME.  i did get the rings and the gaskets already, but not the piston and the cylinder.  This will save me a lot of money.  thank you thank you!

linda

[sidthesloth]

I also saw one that was in California, it was oem, I think it was about $35 but $57 shipping. If you look around you should be able to find a good deal. If you can get yourself a nex kit on the way, I would clean up the piston and barrel and put it back together with the new rings and run it until the new kit turns up. You might be surprised. Good practice to.

[rigpa]

i went ahead and ordered the ebay kit.  how is it that there is such a price difference between this one and the one from the shop?

[sidthesloth]

Middle man makes money, lots of it. A stroker crankshaft from Ruima, sold by Daywot, $189 on sale, from autotech335 $78+$32 shipping.

[rigpa]

so i got the new cylinder, rings, piston, gaskets from ebay.  I went ahead a put the rings in.  it looks like the fatter ring goes in the second ring groove based on the ones i took out of the old piston.  but was wondering:

1.)  if there's a top and bottom of each ring.  i think the number 39 was printed on one side of each ring and i installed them with the number facing up.

2.) do i need to put gasket sealer on both the engine block and the cylinder or just the cylinder.

3.) the head gasket has two distinct sides and i'm not sure how it gets installed.  one side has a depression and an embossed ring like groove.  the other side not so much.  i can't tell from the old head gasket, cuz it was flat as a pancake when it came out.

4.)  circlips are killing me.  i go online for how they are installed and see answers, but do they actually have to fit around that piston bar thingy that connects the piston to the crank arm  or do they just abut that bar?

as always, thanks a million

[sidthesloth]

Good to hear you are on your way, if you are going to use a gasket sealant, use it on both sides of the gasket, cylinder and crankcase. The head gasket is embossed for better sealing, I am not sure which way it goes, i don't know if it matters, but I put the gasket so the inside angle is down, maybe Hoolander can help with this one.
Once you get the first circlip in, push the wrist pin in as far as it will go, making sure it goes through the wrist pin bearing, this should leave the remaining groove clear to install the remaining circlip. before you put the wrist pin bearing in, lubricate it with 2 stroke oil. long nose pliers will help to install the circlips. The circlip abuts the wrist pin.
Yes I believe the side with the writing or numbers stamped on the ring goes upper most. The 39 would be the bore size, 39mm.
Put the first circlip in with the piston out of the engine, when installing the second one, make sure you cover the opening to the crankcase to prevent it from falling in there if you drop it, this can happen easier than you might realise.
Good luck, now you can enjoy putting it all back together, knowing it is almost a new engine.
If you are not certain your oil pump is working properly, you can put 75-100mls. of 2 stroke oil in your fuel tank to guarantee lubrication of your cylinder until you can get the pump proven to be working.

[wordslinger]

..awesome....

[Hoolander2]

IS there a cylinder base gasket on these?  rigpa hasn't mentioned having one, I don't think.  Sorry, don't know which way head gasket goes. 

[sidthesloth]

Yes there is a base gasket, though I wouldn't use a sealant unless I suspected a leak, mainly because I would be expecting to pull it apart again. With the head gasket, I don't think it really matters, it gets squashed anyway.