Badly leaking forks and front wheel install

I've got an interesting one for you guys.

This winter I rebuilt a lot of my '82 KZ750 H3. I've been riding it for the last few months, but have had some issues with the front forks. I replaced the seals last summer because the old ones were leaking. The new seals were great for a while, until I started messing around with the front wheel. About a month ago, the right fork started leaking a lot a lot, meaning I'd clean up the fork, ride 1 mile, and when I got back to my garage fork oil would be dripping from the bottom of the fork. Meanwhile, the left fork was always bone dry. Eventually I figured out that the right fork wasn't flush against the spacer, and the fork was off kilter, causing the seal to leak quite a bit when the fork was depressed. I "fixed" that, and had no more issues with that fork.

I went for a 40 mile ride last weekend, and I noticed now the left fork (that was always bone dry before) was doing the same thing. Same deal, far too much oil for a bad seal. Now the left is leaking and the right is fine. I tried a couple things:
- I tightened the axle nut with the forks depressed
- I had a wood clamp pulling the forks together when tightening the axle nut
- Pulled off the front wheel and inspected the bearings to see if there was any play (no play)

No improvement. Left fork is still pissing oil. It may be my imagination, but it feels like the front wheel "grabs" cracks in the road, and tends towards them, making me think I'm somehow not fully tightening the wheel and axle down. What could I be missing?

Many thanks in advance.

Could a spacer be missing or installed backwards causing the forks to be pulled too close together at the bottom?

I don't think so, I've looked at the parts diagram in the service manual about a hundred times. I was thinking maybe I messed up the tightening order, something like that.

Loosen the nut off the axle and wind it back a few threads, and see where the fork lowers naturally sit. In a perfect world they will be touching but not pinching the wheel.

Next, with the nut still loose, pump the suspension and see what the for lowers do. If they spread out on compression then the stanchions aren't straight.

Last thing - are you still using your air forks? The manual only calls for a few psi, but some members claim that you can have up to 20psi or so. As much as I like the idea of the adjustability of air forks, the best thing you can do is to not put air in them, increase the length of of your spacers, and ass a thicker oil. The air pressure will cause any fork that isn't 100% to leak. And most of these 40yo forks aren't perfect any more.

Thanks, I'll do that tomorrow. If the lowers spread out, what are my options? I'd like to fix what I have if possible.

I do still use the air pressure, but I will consider adding spacers because I might like a stiffer ride. I'm sure it would help with leakage, but I'd like to address the root cause, whatever it is.

The order of assembly and tightening is important, and I agree with Irish Yobbo about the air pressure. There is also the possibility that one of the uppers is slightly bent, and in servicing them, you may have turned it in a way that is causing you grief.

Did you replace the crush washers # 42 with new ones?
they can leak like crazy if not done right.
Note; this is a drawing of a kz1000 fork but I believe the 750 uses them too and I'm pretty sure that a brake line crush washer is what you use.
but make sure

By papaya: .... I had a wood clamp pulling the forks together when tightening the axle nut

That doesn't sound right to me. I'm not opposed to unconventional approaches to repairs, but that just doesn't sound right. Either something is bent, missing or there's a wrong part or something. If the seals are leaking, I would pull the forks & check that the upper tubes are straight. a glass table can be handy. also possible is a bent triple. possibly something else. You could block the engine, then loosen the triple clamp bolts & spin the tubes to see if they spin evenly.

I wasn't able to get to the bike today, but I'll try everyone's suggestions tomorrow. I'm going to try to loosen the axle nut and clamp and work the forks up and down and observe the neutral point as Irish Yobbo suggested. I suppose it's not necessary for the right fork to be flush against the spacer; the clamp should hold it steady relative to the axle. We'll see.

check that the upper tubes are straight

I'm pretty sure they are, when I changed the seals last year I rolled them on my sliding glass door and couldn't spot any gaps. Plus, they were nice and dry for a long time. I will loosen the clamps to see if I can spot anything, though.

You could also eyeball the motorcycle to see if the front end looks straight. mine appeared to be akilter, but the forks were verified straight. Checking the upper triple on a glass table by pressing down on a corner, it moved about 1/4". Replacing it solved the problem.