Race Tech Emulator Setup Advice?

I found the best performance with zero preload on the spring. It's been a while, but IIRC, the blue springs are the supplied springs and I'd suggest to throw them away as they are too stiff. I bought some much lighter springs from McMaster Carr and those were my preference. IIRC, the McMaster Carr springs were something like a 12 or 15 lb/in spring rate, as opposed to the RT springs being about 2X or 3X higher rate.

You'll want to go fairly light on the emulator springs as you're not a very heavy person and the .90 springs will keep the front end up.

The big issue which you will find with the RT emulators, is that with enough experimenting, you will find somewhat reasonable compression dampening performance, but- you will never ever get any sort of good rebound control. The rebound is still controlled by the fixed opening damper rod holes, meaning that your bike's rebound will be in the 1970s.

The size of the top hole in the damper rod will depend on the weight of the fork fluid which you are using. I was using 7.5 (mix of 5 wt and 10 wt), and I welded the top holes shut and then redrilled with a smaller size. I don't exactly recall, but I think I drilled 3/32".

Overall, you will be able to improve the DL650's fork action, but don't get your expectations too high. To get the fork performance into the 2000s, you'll need to pop for a cartridge kit such as a Traxxion or Andreani.

Good luck with it all and hope this helps.

Thanks @Bazooka Joe, that's helpful advice. I did receive some sliver 26 pound springs with the kit, in addition to the 40 lb blue and the even heavier yellow. The general feeling I get reading all these old emulator threads is they're too harsh when people put them in using the blue or yellow springs, so I think I may try the silver ones out, with the stock 3 hole valve plate, 10-15w oil(? some here strongly recommend 15wt or even 20) and see what happens. That's interesting about making the rebound hole smaller, I've only read where guys plug the hole completely, and others who say race tech advises not to touch it (not sure how reliable RT advice is for our bikes, seems like everyone has to deviate from their recommendations). Would you recommend plugging it, or making it smaller as you did?

My goal here is hopefully a front end that gives more feedback and less wallowing in corners (front feels vague and tends to wander just a little at full lean, although a fork brace did help), and off-road a little more plushness at higher speeds over rocky terrain would be nice (might be asking too much though).

Pete, here's a diagram of the emulator valves:

Thanks @Bazooka Joe. I came across an emulator thread from like 13 years ago where you had a lot of good advice there as well. Just wanted to clarify about the rebound hole in the fork damper rod; there's one stock hole that's about 2" down from the head of the rod, but that hole is already at 3/32". That is the hole that people mention to braze/weld, correct? I"m thinking I may leave the hole open for now and see what results I get, and may close them later if the rebound feels too quick.

I just installed the silver springs on the emulators, and couldn't really feel when exactly the spring started to apply pressure to the plate, so I resorted to using a toothpick on a scale to push up on the valve plate, and set them to start opening at about 240g of force (about .5lbs). There's very little pressure holding them down, and I figure it'll be a good starting point. Based on some calculations it seems the usable range for the valve plate is about 3.5mm until fully opened, allowing the same volume of oil as the diameter of the center hole opening, and based on a "toothpick scale test", that would mean the valve starts to open at .5lbs, and 7lbs of force completely opens it. Not really significant on it's own, but could be useful when measuring against the characteristics of the other spring weights I guess.

I've settled on some equivalent of "10 weight" Valvoline Dextron III ATF fluid as a starting point (mostly because it's cheap and readily available). It has a Kinematic Viscosity of 34.5 @40c, right about in the middle of comparable "10w" fork oils (at least at 40c). Comparing data sheets with the popular Mobil 1 synthetic ATF, it is almost indistinguishable in every metric (VI, KV40, KV100 etc.). If it "lasts" as long as Mobil 1 it should be a suitable substitute at a much cheaper price. Mobil 1 and Valvoline both have a Viscosity Index of about 175, so not as good as some of the better fork oils, but on par with others.***

***Based on way too much recent research, the higher the VI, the less susceptible the oil is to changes in viscosity based on temperature changes, so higher is better. If you want your forks to feel more similar in the winter and summer, go with a higher VI index. Here and here are some data tables of popular fork oils, including VI.

I"m about ready to quit reading and start rebuilding the forks tomorrow, and I'll write an update when I get everything assembled and tested.

Got everything buttoned up, set sag, and took it for a 20min quick ride around town. Initial impressions are positive. I need to do some actual twisties and off-road, but it's definitely an improvement. Less fork dive and general upsetting-ness, feels more connected to the road, more feedback. I think much can be attributed to the stiffer fork springs. I'm interested to see how it goes off-road, and on larger high-speed hits.

One note when installing the emulators, you need to be careful to seat them properly on top of the fork damper rods. I watched a youtube video where the guy just basically just chucked them into the fork tubes and called it a day, and I did the same, then had about 30mm of extra preload when I tried to screw on the fork tube tops. Turned out the emulator was canted in the fork tube, and not seated on top of the damper rod correctly, and I had to fish them out and gently coax them onto the seat properly (Props to Joe for suggesting to make a coat hangar "fisher" tool, instantly came in handy!).

Just to sum up my current settings:
145Lbs rider
.90kg fork springs
RT Emulators
damper rod holes drilled out, stock rebound hole unchanged.
3 bleed holes in plate
Silver 26 pound spring ~ 1/8 turn of preload (starts to open with about 6oz of force via "toothpick" test)
Valvoline ATF fluid (about 10 "weight" equivalent fork oil)
About 155-160mm fluid depth (150mm was recommended by RT, went a bit more to try out less air damping)
Forks raised about 10mm in fork tubes (lowered front 10mm).
Fork brace (Good quality one on Aliexpress for $20, one of the best cheap upgrades I've done).

Once I put some actual ride time on it I'll give another update, and any changes I make to the emulators. Thanks again to everyone who gave their input, feel like it put me ahead at good starting point for these.