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· Registered
93 Posts
Discussion Starter · #1 ·
Despite my best efforts, i have lost compression when replacing rings, im installing new std size pistons and rings this time, i have heard a engine builder telling his customer he lapped the rings in b4 assembly, i didnt think much about it at that time, so now im wondering if this will gain me more compression, or at least minimise losses ?

· Premium Member
8,256 Posts
lapping sounds like he is fitting rings to cylinder with a grinding fit or finish, which shouldn't be necessary if you have a good bore hone and rings, big boys do it to eek every ounce of performance buta GSXR?

there is a guy who uses bon ami mixed with water to make a paste and just smears in on the walls then turns the crank to lap with rings in pistons.. meh, might help a little but if your bore and hone is that bad where you rings will not break in on their own something went wrong in the build

the reason the top drag guys do this is cuz they dont run their rings long enough to break them in, so they lap break them in.. so they pre run them in.. rings do this over time naturally, what the diamond hone is all about or Nikasil, again, Suzuki uses Nikasil in their GSXR's and a proprietary CECM (Composite Electro chemical Material) on the Hayabusa..

the way the Niskisil and CECM works is they lay a coat of a Nickel Sodium silicon carbide matrix onto the barrels, it's very thin, over time the rings remove the Nickel from the matrix leaving behind a hard coating of silicon carbide, this makes for a harder slippery surface that reduces friction/heat, allowing tighter tolerances, heat dissipation so forth.. however it takes time for the rings to remove the nickel from the matrix..

if you are not using Nikasil or CECM it still takes time for the rings to "lap" or break in.. at least 600 mile and most manufacturers use a break in oil with a slight slight grit that aids in this ring lap, cam journal, crank bearing break in procedure, why you dump and inspect at 600 mile, that oil and magnet tell you how the break in went..

what was your compression before, after? what motor is it and what work has been done to it? several builders here but more info is needed..

you pre fit the rings right? what did they look like? was there a huge gap at the ends or was it normal?

any work done to the barrels?

how bout the heads? fresh valves and seats so forth? timing nutted?
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