NEED HELP!!!! 185S Needs new rings!

[goump1995]

Well I'm rebuilding my 185s' Engine... (Finally) and I'm getting new rings for it. I mic'd the piston and it shows 2.478inches, which leads to 6.29412 centimeters, which is 62.9 Millimeters. I need to know what size rings to get for the piston. Don't really feel like ordering the wrong thing!!

Thanks

-Travis

[barnett468]

Hello goump1995


You have a 63 mm bore x 57.8 mm stroke so your bore is std, congratulations. You can use stock rings, do not use chinese. Someone here can recommend a quality brand.

Now the bad part. I guarantee you that your 30 year old std bore cylinder is worn out. Many people here will simply tell you to just "deglaze" it and it will be fine. It will not. Yes it will run, yes the rings will never seal because your bore is not "true" yes it will have lower than optimal compression and probably smoke due to the worn bore. You must measure taper and concentricity in two radial positions on both top and bottom of cylinder 90 degrees apart to determine amount of wear. Any concentric wear in excess of around .001 is too much. Any taper in excess of around .015 is too much. You also need to measure piston to cylinder clearance, anything in excess of around .005" is too much.

If it is just slightly worn you can have it trued but this will increase the size to a point where your piston to cylinder clearance will be too big.

I personally would prefer to do it once now that it is apart and not do it again in a week.


Hope this info helps

[barnett468]

Hello again


The most wear will be approximately 1/2" from the top in a position that runs "front to back" not "side to side" since this the direction the piston "rocks" at the too of the stroke and the least wear will be at the bottom in a position measured from "side to side" not "front to back" since the piston never touches here.


Hope this info helps.

[Dave8338]

GREAT info, Barnett. This applies to all vertical bore engines with cranks that run opposed to the bore, for those just wondering...

[goump1995]

Thank you so much! I'm going to go ahead and measure the bore in the cylinder and give you guys the measurements to see if you guys think I should get it oversized. This engine wasn't used much and sat in my dad's shop most of it's life.