Steering head bearing adjustment ring nut

I replaced the steering head bearings on my 2006 TC 450.

My problem is that I cannot get the steering head bearing adjustment ring nut tight enough to prevent the steering from clunking when the front wheel hits a low obstacle. I have spanner wrenches (not the correct size, of course), and I have made a special tool from a two inch diameter piece of pipe with 4 protrusions to grab all four slots at once with the handlebars off, but with two people I cannot get the nut tight enough. I can understand a bit of retightening should be required as the new grease gets pushed through the bearings but this is ridiculous! I can feel the steering getting tighter, but it's just not enough. I am ordering a new adjustment nut (as mine has now taken a bit of a beating) and the correct size spanners to try this from scratch again. Anyone else had troubles like this? Anyone know why I'm having such difficulties?

Thanks

I jus use a hammer n punch. Shouldn't be too tite or you'll damage the bearings n steering be notchy

Are you sure you have the right bearings ?

If you can adjust the nut up tight and there's still play in the bearings then the bearings are fooked and it's time for new ones

it almost sounds like you've lost a set of balls somehow. something is wrong- that's for sure.

Didn't leave the retainer ring thingamajig(bit that the bearings sit in in the headstem) out did ya?

Steering nut should not be that tight. Maybe the thunk is in the initial stroke of the forks. As stated above check your steering stem bearings. Another thought , have you checked your wheel bearings for play.

Thanks for the comments...
The upper and lower bearings and cups on the steering stem were both replaced.
I recently replaced the front wheel bearings so they are good.
Bearing kit I ordered from the shop and they looked the same as the ones that came out, they should be fine.
I replaced the front fork seals at the same time as I replaced the steering bearings but I don't think it's from the fork. The clunk is only felt when hitting a low object, not at some particular compression of the forks.
Last time I tightened the nut the clunk went away momentary for a few bumps but then comes back.
Weird. Probably I will just keep trying to tighten it and ultimately ride it until something breaks, I guess. Pretty annoying though.

Hold it... you did wheel bearings and fork seals also?? why do you think it's your stem bearings?

put the bike on a stand. yard on the front end: to & fro, up & down, side-to-side, and then rotate it (there should be no play and a smooth rotation- if it passes this test, your triple clamps/stem/bearings/handlebar mounts are probably good. maybe). what you're describing is weird.

wait- ....what?? no, dude- do not do that. something is wrong; figure it out.

Ok I think you may have got rid of the washer that sits under the bearing on the steering stem. I forgot to install it below the bearing on the stem one time and the headset would not tighten up no matter what I did. I wonder if it was stuck to the bottom of the old bearing ? This washer will make all the difference even though it does not seem like it would.