I found the level exactly at the factory spec, 75mm.  I wanted to see what would happen if I lowered the level, so I removed oil until the level was 100mm.  Took it for a torture test.  To me, it seemed better.  The front end didn’t seem to kick up as much on the abrupt stuff.  The zip tie on the front fork now indicated that the forks were using about 1/8” more travel.  The forks were stroking 4” or 79% of available travel.  It seemed better???

Howzabout lowering the oil level some more.  I removed another 20mm of oil, so now the level was at 120mm.  The fork action seemed really smooth.  The zip tie showed it was now using 4.22” of available travel (83%).  It seemed better, but still harsh.
 
I decided to try a lighter weight oil.  Belray 10W seemed prudent. First, I ran 30 ml of the stock oil through my burette.  It took about 25 seconds.  Then the Belray 10W.  It took about 19 seconds.  OK.  The Belray is thinner.

I made an oil removal tool from a piece of brake tubing.  Thirty inches of 3/16” tubing was just right.  Use a tubing cutter to cut off one of the flares.

Drained and filled both forks to 120mm with the Belray 10W fork oil.  To me, it felt better but what do I know.  It seemed smoother, more compliant, but still harsh.  Didn’t seem to kick up as much in the front.  The zip tie showed it was now using 4.53” of travel (89%).  Is this a good thing, using almost 90% of the travel????

The new rear shocks and front springs arrived.  I thought I had the front end working pretty good.  Time to try out some new boingers on the rear.

First order of business was to enlarge the ½” bushings to 14mm.  I drilled them out with a 17/32” drill and then used an expandable reamer to enlarge each bushing to 14mm.

I already knew I could expect interference problems from the lower belt guard.  I lobbed off ¼” from the front edge of the guard.

I did not touch the belt adjustment.  It’s loose when the rear wheel is off the ground but it’s still gonna have to swing through the tight part of the arc.  Doesn’t make sense to try and adjust it.  

Versy, thanks for the heads up on the bolt on the shifter housing.  I trimmed it back just to be sure that there’s no contact with the belt.

It didn’t lean over too far when on the kickstand.

Time to set the sag.  I measured the rear wheel travel at 3.56” (90mm).  So, I gained about .87” travel (22mm).   Looks like the target race sag will be 27mm and target free sag will be 7mm.  The closest I could get to those target sags was with the preload set to the stiffest setting (#5).  Uh oh!  Looks like those 90/130 springs might be a little soft.

Did I screw this up?  I weighed myself again.  Yep, 185 lbs.  Throw on the riding gear and I come in at 194 lbs.  Oh well, why not try it.

One nice feature on these 412s is there’s a slot in the spring retainer.  Makes it easy to check how much the shock travels.  Just shove a chopstick down the opening and push the bumper stop all the way down to the shock body.  Ride it around and you can see how much the shock traveled.  The bumper fits real tight on the shaft so it will stay at the highest point it reaches.

I did all sorts of tests.  The #5 preload setting was best, and the best wasn’t good.  It bottoms out, and that hurts.  I ordered a set of 115/155 springs.  These 90/130s are too soft.
 
I have come to a conclusion.  This contraption is called a shock absorber.  It’s supposed to “absorb shock”.  Once it goes on the bumper, it no longer absorbs shock, it transfers shock.  Then the rider (you) becomes the shock absorber.  Ouch!

I think the same holds true for the forks.  After some pondering, I’m thinkin that the forks go on their bumper (which is hydraulic) at around 85% of total travel, give or take a little.  Once the fork tube starts to overlap the compression dampening holes in the dampening rod, oil flow starts slowing down BIG TIME.  And then the tube starts to engage the “oil lock” (Pc 11).  Man, that’s gotta stop it dead.  When you stroke the forks by hand you can feel all that start to happen about the last one-half to three-quarter inch of the stroke.  It’s essentially a hard stop or “bumper”.  I’m thinkin you don’t want those forks or shocks hitting the bumpers on a routine basis.  It’s a revelation, an epiphany.  Why didn’t I think of this sooner???

DragBikeMike’s New Cardinal Rule of Suspension: You want it on the springs at all times; you never want it on the bumpers.

Do I have that right???

After fiddling around a bit with sag, I ended up with 77mm spacers.  I tried 95mm spacers but there wasn’t enough sag.  Electrical conduit works great for these spacers.   The spring kit comes with a chunk of plastic pipe, but I opted for the metal stuff.