piston ring size need help

[espears]

I have an 86 spree with a scratched up piston and sleeve, I have read that the piston can have scratches since the rings are what make the seal against the sleeve, but the sleeve will need to be replaced. Does anyone know if this is true, and also what is the part number for stock 86 piston? There are a bunch of different rings on the microfiche parts websites, some part numbers would be helpful.

Thanks

[timcat]

By sleve do you meen the jug?

[Kenny_McCormic]

Jug can be bored if scoring is deep.

[espears]

Yeah jug, how much does it cost to be bored? Doesnt that mean new piston and rings, im trying to get this running cheaply as possible

[Kenny_McCormic]

A boreing will require the purchase of a new oversised piston and rings. Best to buy the piston first and have the shop match the bore to the piston.

[Wheelman-111]

Greetings:

It all depends on the depth of the scratches in the cylinder walls. If they don't quite catch a fingernail, a wise old Forum member used to say, you can get away with honing the cylinder. A hone is a contraption that attaches to a drill and looks like this:

http://www.harborfreight.com/cpi/ctaf/d ... mber=97163

Note that the size of this one is too small for your 40-ish mm bore, but they make all sizes. Hook it up to your trusty black and decker AFTER you measure the cylinder as it stands now, at three levels at least - top, middle, bottom. Then go to town. How much material you remove will deterime if the piston can go back in.

It can always go back in if you're making the hole a bit bigger, but may not work right. Piston slap is a noise caused by a too-small piston or worn cylinder - the piston rattles around in there as it changes direction about two hundred times every second.

If the scratches are deeper than a hone can remove, then a bore job is necessary:

http://www.harborfreight.com/cpi/ctaf/d ... mber=33562

Unlike a hone, a cylinder bore tool needs precision guidance with big heavy machines to produce accurate results. The idea is to remove a precise, known amount of material. This takes out the grooves and scratches and creates enough room in your cylinder to insert a specific "Oversize" piston, available from the manufacturer in 1st, 2nd, etc. sizes. If your standard piston is 40mm, for example, the oversize available might be 40.125mm, 40.250, etc.

I've never had a cylinder bored, so can't say how much it costs. Maybe someone here can help you. Machine shops charge to do this - you make your own deal wherever you are. Call any dealer or machine shop and ask. If you are quoted a price, maybe help someone else by posting? That's how we help each other. I'd like to know myself.

[keithw]

The last cylinder I worked on had a pretty good line scored into it. After honing it turned out to only be a thousanths or two deep. Not enough to need a bigger piston. Looking at it I would have sworn that it was going to take a rebore. I would hone first, then measure, then decide on the rebore. While honing keep the stones flushed off with mineral spirits. If you don't they clog up and not cut well.

It's been a very long time since I had a shop bore a cylinder for me. At the time it was only about $20. Now I wouldn't be surprised if it was closer to $50.

keithw

[scooterwerx]

the local star auto parts store is 40$ for a single cylinder...