what causes cylinder pitting?

[DnB_racing]

im doing some maintenance on my 06 and I noticed that the nikasil coating on my stock cylinder is pitting and lifting or separating from the aluminum. I have kept up on my ring changes on high comp. piston. when I change the rings I have it deglazed, is it just that thin of a coating that 3 deglazings has worn out the coating? if so should I deglaze ever ring change?

[RobRacing]

What kind of hone were you using when you deglazed? You can't use a regular bur type hone on a nikisal coating as it will damage the coating. You usually don't need to hone unless the cross hatch marks have been worn out. So if you have honed aggresivly 3 times it may have worn out the coating. I am not sure if this is the exact cause of the pitting but in theory it makes sense.

[DnB_racing]

I didnt do the deglaze but the type was the small stone balls Im not sure what its called they have a bunch of wires with little balls on end? is that the wrong type to use? they called it a deglazer so i thought it was for the job, the honda shop did if for me and I hope they know which one to use,I dont. all the piston companys say to deglaze before any new rings. what do you do before new rings?

[Baileygunns]

It's a wear item... If you have done 3 sets of rings in that thing I bet it's just worn out. How many hours do you have on the jug?

[DnB_racing]

around 300 hours on the jug, Im wondering if I shouldnt deglaze every ring change?

[Baileygunns]

Not if you can see the cross hatch. The glazing is usualy burn oil.

[DnB_racing]

I was just reading if cross hatch still looks good just wash with soap and water and scotch brite. thats what I think Ill do from now on

[Baileygunns]

You can use a fine steel wool too...

[DnB_racing]

It looks like I caused premature wear on the cylinder buy deglazing every ring change. this new cylinder I will only deglaze if crosshatch is worn or scratched. live and learn I guess!!

[Baileygunns]

Depends how deep the scratch is...

[DnB_racing]

this problem is probably self inflicted the more I think about it. the coating is thinner than I thought only .003 so Im pretty sure that 3 deglazing and 300 hours of friction just started to were the coating down.if I dont have any marks on cylinder then rings are going in from now on no more deglazing unless absolutly nessasary, I know that its recomened for the proper seating of rings so I guess ill have to judge the condition each time.

[Baileygunns]

Proper seating of the rings has to do with cylinder pressure...

[RobRacing]

Yeah the hone you used is a bur hone and its the wrong one. The hone for nickesal looks like a bunch of thin strips of emory cloth in a spiral form. When you seat the rings you are more or less forming the edge of the ring to the cylinder wall. The main purpose of the cross hatch is to promote good seating of the rings to the cylinder. If the rings are not seated properly you will lose some compression and get oil blow by and such. But I mean really unless you are a pro I think changing the rings all the time is a little unnecessary. How often did you change them?

[DnB_racing]

I deglazed first when new piston 13.5 went in, then rings were changed after 2 seasons and deglazed it again. and before this season after about 200 hours i changed again. I will still change rings about every 200 hours,but Im not going to deglaze unless nessasary.I drag race quit a bit and I fell safer with rings that are inspected, If I remove the piston from the cylinder I was told that the rings should be replaced no mater how many hours, is this correct?

[RobRacing]

From what I know you don't need to change the rings if you remove the piston from the cylinder. I don't really see any good reason for doing that. The only thing that you have to replace is the head and base gaskets. I personally would replace the whole piston assembly after every riding season rather than just the rings.