Piston sleeves

Hi to all.I was once told by a "motorcycycle expert"[his words]that after reboring the sleeves should be polished to a mirror-like finish to prevent ring and sleeve wear and to seal the whole lot much better than the honing done by the shop.Any truth in this tale?

Never heard that one before.

The idea of honing when replacing piston rings or after a re-bore is to "Cross Hatch" the surface of the bores (posh name for scratching)so a microscopic amount of oil is retained on the surface of the bore to lubricate.
The cross hatching should also be at 45 degree patterns to ensure full effect.

If the bores were polished smooth......as your mate states......then the above procedure would not come into effect & i think you would be more likely to "glaze" the bore surfaces, which is not good for oil consumption.

I do know some competition type 2 stroke bikes have chrome bores from new, but obviously have the added benefit of lubrication in the fuel as well as the engine.

Pete F

Thanks Pete F,yeah there was some beer involved,your explanation makes sense.

Tell him to do it to his bike and as Pete said about the crosshatching use that on your bike.
The BMW bikes have used a Nikasil bore lining which is their word for a chrome bore and it has to be given a medium/coarse hone if you fit new rings and even after 400,000 miles I have seen the crosshatching still visible on all the bore surface but the rings were so worn it had virtually no compression.

Rick,

Thats really interesting. I was not aware of that with BMW.
I worked with BMW UK & DE Motorad over many years in the late 80's & early 90's.
Great company to work with & learned a lot.

Pete F