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Posted: Wed Sep 16, 2009 2:07 pm Post subject: Replacing piston rings - to hone or not to hone?
Hey folks,
I'm looking to replace the piston rings on my '71 T350. The old rings are worn way beyond the specs.
My dad was saying that usually you want to 'break the glaze' off of the cylinder walls before you put the new rings on or else they won't seal against the cylinder wall properly. Is this something that should be done even for a little 350 two-stroke?
Joined: Jan 05, 2009 Posts: 622 Location: Michigan
Posted: Wed Sep 16, 2009 4:01 pm Post subject: Hone or not
Well, it sounds like your dad and I would get along fine, I have always believed in honing cyl. walls if they are shiny smooth and sometimes removing a ridge that occurs at the tdc point, but, I'm a four stroke kind of guy and am not real sure on the 2 strokers. I know I hone out brake cylinders when I rebuild them and they are 1 strokers, so to speak, but ultra low rpm. LOL I am sure someone with a tad more knowledge will add to this. Do you have a repair manual to refer to? In any case, hope it works out.....Blue
Joined: Dec 26, 2007 Posts: 1282 Location: Scottsdale, Arizona
Posted: Thu Sep 17, 2009 8:17 am Post subject: Re: Replacing piston rings - to hone or not to hone?
thomass wrote:
Hey folks,
I'm looking to replace the piston rings on my '71 T350. The old rings are worn way beyond the specs.
My dad was saying that usually you want to 'break the glaze' off of the cylinder walls before you put the new rings on or else they won't seal against the cylinder wall properly. Is this something that should be done even for a little 350 two-stroke?
Thanks!
Tom,
Your dad is right. It has to be done even for a little 50cc, two stroke or four. If you don't hone the cylinders, the rings won't seat in properly. You'll have a lot of blow by and lower compression than normal. But there's more to it than that. If the end gaps are a lot wider than specs as you say, you'll need to measure the bore for taper, out of round, and general wear in the ring area. Otherwise, you might find that your new rings also have excessive end gap. Measuring a used bore requires specialized measuring tools. Take your jugs and pistons to a machine shop, and have them mike the bores and measure the piston clearance. If the dimensions are within specs, hone the cylinders and install new rings. Otherwise, bore to the next oversize, chamfer the ports, and install new oversize pistons and rings.
Joined: Sep 05, 2009 Posts: 4 Location: West Kelowna, British Columbia
Posted: Fri Sep 18, 2009 10:20 pm Post subject:
For sure you need to hone the cylinders before new rings regardless of engine size...........and like Bikegeezer said, make sure your cylinders aren't worn out. Get them measured up and if they are out of spec you'll need a rebore to the next size up. If that's the case next oversize piston and rings will be needed as well.
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