Honing Nikasil

[rumblefish]

I'm rebuilding the top end on my bike, and I always hone the cylinder when replacing parts. I've heard that your not supposed to hone a nikasil plated cylinder, but I don't believe it. Is this true?

 

[RM_guy]

Yes you can hone the cylinder. You can't bore a plated cylinder but you can, and have to hone it to add the cross hatching which retains oil for lubrication.

 

[DMATT125]

rumblefish,yes you can hone your nikasil cylinder. i "think" a 240grit. you can also bore your cylinder,you just have to get it replated.

 

[DKT735]

Ball Hone

I run a ball hone through my cylinders at every pistion and ring change. It cleans things up pretty good.

 

[CC_RIDER]

DKT735, I was wondering about a ball hone, but thought the balls might hang up in the ports, or round off the leading edges, etc.

You say it works pretty good?

 

[DINGUS]

DKT735, please explain the process of using the ball hone to CC_RIDER and me - I think he may have the wrong idea of how its done. I have my cylinder done at every rebuild too - but i don't do the honing myself so I really can't offer any wisdom - Isn't the hone run carefully by hand just enough to make cross hatching on the surface? - I may be wrong, but thats how the cylinder looks afterwards.

 

[WoodsRider]

...and have to hone it to add the cross hatching which retains oil for lubrication.

Actually the original cross-hatch should still be somewhat visible in the cylinder, unless a major failure occured. These are actually small valleys in the surface that retain lube oil during operation. The ball hone is also called a glaze breaker. It creates small peaks in the surface to help seat the rings to the cylinder. If the rings don't properly seat you won't get proper sealing and as a result lower compression and firing pressure due to blow-by.

A new or replated cylinder is usually honed with stones mounted in a Sunnen type honing machine. This keeps the bore straight and perpendicular to the cylinder surfaces. It will also have a plateau type surface with a specific finish.

 

[DKT735]

WoodsRider is right the sunnen hone is long enough to extend from one end of the bore to the other and is used to get an exact cylinder to pistion clearance and a perfectly round cylinder no taper.

The ball hone is different, its intended to just clean things up. The edges of the ports should be rounded and shouldn't have an edge to them. I only run the hone up and down throught he cylinder about 10 or 20 times with an variable speed electric drill about a quarter to 1/2 of the way on. It cleans things up nicely.

 

[rzracer]

I use a BR 180SC in my iron liners and 240AO in my plated aluminum bores. It's an easy thing to do yourself, just don't go hog wild in the bore (you just want to remove the glaze and x-hatch). BR flex hones come 10% larger than the size you by. So if you have a 2" bore and order a 2" hone, the hone will be 2.2". Some people will will tell you to order a brush 10% smaller than your bore so the balls won't go to far into the ports, but the tech I spoke with at BR does not advise this as you do want some pressure. Just use the closest size hone available to you bore (they are avail in .125 increments). The AO (Aluminum Oxide) are not as common and mine had to be made at BR after I ordered it so it took awile. At $25-35 one use will pay for itself though and they last a long time.