Thank you folks for all the great input! I adjusted my notifications so that I know when you answer....sheesh, my bad.
I got the TKC 80s installed and spokes tightened/wheel trued. I put 34# rear and 32# front, as I was running me (215#) and 110# of camping gear (30# for each loaded sidebag, 16# for the loaded topcase, 18# for a loaded Drybag 350, 13# for a loaded Drybag 260, and 1.5# in each loaded crashbar Drybag 80). Total rider/gear weight of 325#. A high load but certainly not the "Most Ever".
I set the forks at the stock height (cap bottom at triple clamp surface) and set the rear preload at 5. I set rear damping at full soft in order for the wheel to handle small sharp edged rocks without pumping down. I measured rider sag with full load at 61mm front, 86mm rear, (i.e. 0.3 of F travel, 0.46 of rear travel). These sag figures are about 10mm more than just me on the bike with no bags or camping gear, and the shock preload at 1.
The slow speed wobble is more an oscillation, as it starts with the front wheel getting pushed sideways by the terrain and the "wave" travels to the rear wheel. It feels like there is a vertical hinge in the middle of the bike and the front and rear wheels are not tracking straight. Think of how a fish moves in the water...that's how it feels.
I ran the higher tire pressures because the bike was "camping loaded" and because the oscillation is damped by higher tire pressures. Any terrain more aggressive than a flat dirt road is impossible. Any car tire rutting in a dirt road will get the oscillation going. As it was, even with the higher pressures, on flat dirt roads I couldn't go above 20 mph or the oscillation grew strong enough to dump the bike. We accidentally took a wrong turn and hit a "4wd road" with two 7" deep car tire ruts and I got my workout for the week trying to keep the bike upright. I would have lowered the pressures to proper dirt pressures, but didn't want to increase the tendency for the bike to oscillate. Obviously with the higher pressures the general tire performance in the dirt was substandard, but I am impressed with the TKC 80s performance both on road and on dirt so far.
I am able to recreate the oscillation at a stand still by holding the bike up, standing next to it, and *quickly* cycling the handlebars back and forth about 3-4" about 5 times and then letting go of the bars...the bars continue to oscillate back and forth about 5 times with the front end shaking the entire frame of the bike back to the rear wheel. (Full gas tank, full camping load)
The change in tires, spoke tightening did nothing to correct the oscillation...it is not the tires or spokes. Wheel bearings are also good.
I checked the frame for cracks and did not see any...though it is possible, but unlikely, that there are hidden cracks. The bike had 800 miles on it when I bought it and it was in good condition...no wrecks.
Note that the only time I feel the oscillation on an asphalt or concrete road is when braking from 5 to 0 mph, accelerating from 0 to 5 miles per hour, and doing slow speed u-turns. At any speed over 5mph on the asphalt or concrete there is absolutely no problem.
If this was a standard problem, I would expect that this board would be aflame with upset NE owners who tried to carry camping loads or aggressively dirt ride their NEs....from what dirt road and seldredg said above, there are many NE owners who have at least some version of this problem.
I pulled all my loaded bags off and tried the bike "WR250F style". A majority of the oscillation was gone, but I could still feel it in more extreme rutted conditions. The added camping load makes the oscillations worse, but the camping load is not the primary generator of the oscillations.
Note my co-rider (~170#), on a stock 09 KLR with 15K miles and with 90# of camping gear, was able to ride with none of the oscillation feeling at all. He had no problems. I rode his bike and tried my standing oscillation test. His bike tracked properly when I rode it, and in my standing test I could feel the same "wave" in his bike when I did the standing test BUT it only cycled once, and it was of MUCH less amplitude than the oscillation on my bike.
I pulled the steering stem out and am replacing the races and bearings. Those I took out looked ok, but I want to eliminate each possible source of the problem. I will, of course, torque the new bearings properly. New bearings never hurt.
My forks sits two inches higher than the 09 forks at static. It is not lost on me that this means that there is less overlap between the upper and lower fork tubes, which can lead to more bending between the two tubes...especially given that the front damping is so ridiculously stiff. I can imagine the two tubes bending against each other when the oil locks on quick impacts. I will check the forks to make sure they have the same amount of oil in them and that no one has screwed up the internals, and raise the tubes in the triple clamps after measuring the max distance that I can raise them. This will obviously weight the front end, causing the forks to compress more (more overlap, less bend) and steepening the rake (quicker turning more amenable to slow speed handling). I will also test 5 weight oil in the fork to soften the damping. Raising the forks and testing less viscous oil are, of course, an interim proxy test for getting the right spring and lowering the damping through DDCs. If raising the forks and putting less viscous oil substantially eliminates the oscillation, then I know that fork geometry/function/length is a primary cause and so I could reasonably spend $$ for Cogent rider-specific springs and DDCs. (As with some folks above, I also don't want to spend $$ only to find it doesn't help).
If raising the forks and testing 5W fork oil does not make any change in the oscillations, I will change the bearings on the swing arm. I already tested it for looseness and it was not loose. However, again, new bearings never hurt anyone.
If the new tires, good wheel bearings, tightened spokes, new stem bearings, raised forks, proper amounts of less viscous fork oil, and new swing arm bearings does not eliminate the oscillations, then I am left with one conclusion: the NE wheel-fork-tripleclamp-frame-swingarm-wheel engineered system is not strong enough to handle a camping load without flexure.
Based on my experience, I agree with dirt road that the most likely cause of the problem is the NE suspension...the bike sits higher in front (less overlap between upper and lower fork tubes, longer total fork length imparts higher side loads to the steering stem, and creates "Easy Rider"-style handling via the raked fork), and the compression damping is stiff on both the forks and the shock which helps keep the suspension extended on sharp hits and transmits impact loads directly to the bike. So, hopefully my test will reveal that the suspension is the culprit and I can then justify the $$ to get custom springs (shorter, softer) and DDCs (less damping) tailored to me and my riding style.
I will report back as I go through it.
Thanks again for the feedback!
Last edited by Yeravener; 06-30-2019 at 11:03 PM.