Topic: Piston ring Land and ring side gap on Emgo pistons seems too tight

[denisj]

Hi All
I am assembling a 750 here and I am noticing the Emgo pistons that were give to me to install have an immeasurable side gap for both the 1st and 2nd rings (the gap between the ring land on the piston and the ring) I can not force a .0015 feeler in there and according to the book .0016 is the minimum for the top - .001 is the min for the 2nd. The are much too tight and seem to have a drag when turning them in the piston. I feel the rings may be too thick or the pistons are made incorrectly.

Has anyone seen this and run it? This is much much tighter than the 1 new ART piston I have lying around here. The factory piston is measuring .002 on the top and .002 on the 2nd - just about in line with the used pistons I removed from the bike. That seems very normal to me considering the Brit twins I see lots of are in this range or looser.

I would appreciate any advice you may have on this. Thank you!

[754]

I had a set of firged pistons, rings were tight. Decided not to run them. Top ring only I think.
I would probably try taking a  thou  or so off, but ra  out of time.
 With a Micrometer ,and  sandpaper on glass,  it would take a while.. plus chrome rings , got to ge careful, don't know If it would hold up ?

[scottly]

According to my old auto shop textbook .0015" is the minimum clearance for a top ring, checked with the ring set into to groove from the outside, not installed onto the piston. Are there any burrs on the grooves, or on the edges of the rings? You might be able to lap the rings using 400-600 grit wet-or-dry sandpaper on a sheet of glass or other flat surface.
Frank beat me about using sandpaper on glass. If there are only tiny burrs on the edges, it shouldn't take too long to knock them off. WD40 makes for a good lube for this.