Recumbent - Need to stop an USS handlebar from rotating in the stem

On my USS Performance Blaze recumbent, I cant lock the stem around the handlebar tight enough to prevent the bars from pivoting front to back. Does anyone else have this problem? Is there a solution?
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thanks, Don
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I'm considering wrapping the bar with emery cloth before clamping it in the stem.
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Oh, and does any one know where I would find the bike's serial number or other ID for Home Insurance inventory?

I don't understand what you're asking. You want the handlebars to easily pivot about the stem in both directions, don't you?

The wedge is the thing that keeps the handlebar stem from falling out of the fork tube when the handlebars are upside down, compared to an upright bike. The hex bolt (use an allen wrench) is what you tighten to snug the wedge inside the fork tube so it doesn't fall out. Turn it clockwise to make it tighter.

I guess I didn't make it very clear. The bar rotates around its own axis, slips in the clamp so that the bar ends come toward me if I pull or move away from me if I push. Emery paper made it a lot better and on another thread someone suggested skate board grip tape (adhesive one side, grit the other I assume).
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Thanks for your thought.
Don

Cheap fix: Use a piece of beer or pop can as a shim. Tighten bolt.

Oh, I see. Yes, the aluminum can shim -- that's a great idea.

Thanks everyone. It's OK for now, but I'm going to get to the vendor. A new bike with shims/tape doesn't seem right. Otherwise it's a very nice bike.
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Don

When you tighten the bolts to hold the handlebar, are the two halves actually coming together? If not, then maybe the bolts are bottoming out if they don't go all the way through the stem.

Thanks everyone. I think the villain was the paint/coating. The bar is black ferrous material. The bike's new so I'm paying attention. When I took out the emery cloth, to check, the grip was still good, no movement.
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Dchiefransom the two halves of the clamp never touched and the bolts thread into weld on nuts. I was afraid I'd strip the nut initially. The real answer was roughing up the bar.
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thanks, Don