Cylinder honing question

[basstracker1970]

Just a quick question on cylinder honing. I have a 1983 mercury 80hp I am rebuilding. What honing technique is better? The ball hone or the regular stone hone on these engines? Thank you in advance for any help....

 

[Faztbullet]

Re: Cylinder honing question

You need a rigid hone like a Sunnen to check for cylinder taper & wear as it will show up in about 30 seconds of honing and give the proper finish. A spring loaded hone is worthless and ball hone or flex-hone is a surface finishing tool, not a material removal tool.

 

[sschefer]

Re: Cylinder honing question

First you need to determine if it's boring or honing that's needed. I don't know what tools you have but a bore gauge is the tool that's needed at this point.

Most Merc engines allow .006 out of round and/or taper (not cumulative) before boring is required. If you're at .004 out of round or taper, honing with a Sunen Mobile hone will probably correct it but you'll be at the max for acceptable ring end clearance with standard rings and realize a significant power loss compared to just having it bored and honed .015 +- .0005 by a machine shop. You would have to replace pistons though.

At .002 out with no scuffing on the old pistons or scoring on the walls you can use a 400grit ball hone to clean the cylinders up. Some race engine builders actually prefer the ball hones because it's hard to make a mistake and they tend to automatically chamfer the ports and help to prevent ring hang. They should only be used for minor cleanup. A plateu hone is often used for final dressing.

 

[Faztbullet]

Re: Cylinder honing question

I prefer 1st timers to use a ball hone due to simplicity, just inspect ports when washing for discarded "balls" and use one just for your standard bore size. Stuffing a 3" hone in a 2.875 bore just "swirls" the cylinder so use a 70mm or 73mm. I only use a flex-hone on smaller engines due to the stones I use on my hones and the cylinders being a "blind hole". I hone all the larger bores with a Sunnen AN hone. What you want is a good crosshatch that hold oils to cylinder walls(see below) and its not hard to get with a ball hone if you go slow and use proper size. I only use a cats wisker hone(plateu) for special engines that need slick finish such as my B&S kart engines or customer requested engines.

 

[sschefer]

Re: Cylinder honing question

Agree, the plateau hone works best with a tight tolerance motor that's usually all broke in within the first 30 minutes anyway.

 

[bktheking]

Re: Cylinder honing question

My father achieves that same cross hatch pattern as in the pic every time on every single motors he's ever done. He uses the spring style with makita drill , I guess he's just a good old school mechanic.

His picture is in my garage as my mechanical inspiration, amazing man he is.

 

[basstracker1970]

Re: Cylinder honing question

Thanks everyone for all the great imformation. The motor im working on is a 1983 merc 80hp. All im wanting to do is clean up the cylinders for a new set of rings. What grit ball hone should I use?

 

[Faztbullet]

Re: Cylinder honing question

What grit ball hone should I use

320-400

My father achieves that same cross hatch pattern as in the pic every time on every single motors he's ever done. He uses the spring style with makita drill

You can get a good crosshatch off spring drill hone but it will follow the cylinder imperfections if any as its not rigid. A rigid hone after about 10 passes will show the worn/tapered areas of cylinder as dark spots where stones did not remove material. The Merc inlines are almost always worn at transfer ports due to side thrust of piston and I rarely see a inline that doesnt not need to be bored....

 

[bktheking]

Re: Cylinder honing question

Ya I figured, honing is useless on some motors and boring is the only way to go.