Triumph makes a pump that adjusts the oil level, but it doesn't drain the fork. Silly, I know, to go to the trouble of having a special tool that sucks out oil rather than just making a drain at the bottom. Just like Flip, I see little things all over that could have been handled during manufacturing for mere pennies more. I suppose all those pennies add up in the long run and "do-it-yourselfers" are fewer than we think. To a shop with space and equipment, removing the forks to turn upside down isn't that big of a deal ... but from an owners maintenance point of view it's more work we just aren't willing or able to attempt unless we have the time and ability. That probably keeps dealers service depts busy.
A turkey baster works just as well.
It's not just Triumph (that deleted the drain plugs), it's all the manufacturers.
USD forks cost less to make because there are fewer parts but they are exponentially harder to maintain.
Problem is, if you 'suck' out the fork oil (if you could, you can't because the valving is in the bottom of the leg, so you can't get to the bottom anyway), you'd leave all the crud in the bottom of the fork leg anyway. So you remove the legs (after taking apart the front end), loosening the triple clamps, removing all the junk attached to the forks, and invert them....and you still need to flush each leg with mineral spirits because the crud sticks to the inner walls and parts inside.
I'll probably take some flak for this but, if it was me, I'd flush and change out the fork oil when installing the Progressive springs because just replacing the springs leaves all the crud ans contaminated (from moisture ingress) oil in the forks and no, I'm not going to offer machined with drain ports fork legs on an exchange basis. It's actually a straight forward machining job when the legs are removed and disassembled.
It's a matterf of finding the lowest point in the leg and securing the leg in a V Block and drilling, tapping and spot facing the leg to accept a washered drain bolt.
Then it becomes a matter of changing fork oil viscosity to change the dampening instead of changing out the springs. All the progressive (or any other manufacturers) springs do is firm up the ride (no matter what kind of hype they blow about).
It's the dampening that controls the ride and handling characteristics, not the spring rate and fork travel is limited by the mechanics of the assembly, not the springs installed. In actuality, changing out the springs is a band aid on the real problem, if, it's a problem at all. Spring and dampening rates are designed into the suspension to suit the average rider. A manufacturer can't make everyone happy. Clicker shocks, cartridge emulators and remote reservolir's can....at a price of course.
In a nutshell, when you compress your forks (like hitting a bump or a pothole in Michigan

, what happens is, as the fork compresses, it's similar to a hydraulic cylinder except the oil has to go somewhere. In a hydraulic cylinder, the oil is displaced into a hose.
In your forks, the oil is displaced through metering orfices machined into the metering rod and allowed to move into the upper cavity of the fork. It's the metering orfices that control the dampening and handling, not the springs, which, only serve to maintain ride height and provide initial resistance to movement.
That's why, installing heavier springs makes the bike ride worse. It may improve cornering but it does because of the increased resistance to movement, the dampening is unchanged in either rebound or compression. Afain, the dampening in either direction is controlled by the internal metering orfices, not the springs.
The only economical way to change the dampening and the handling is to change viscosity of the fork oil. The metering holes are a specific size and number and they only allow so much oil to pass at a given viscosity. Increasing the viscosity, increases compression and rebound dampening, decreasing it, decreases the dampening, which, is why fork oil comes in a wide range of viscosities.
That's why aftermarket rear shocks 'feel' so much better. OEM rear shocks have little compression dampening. They rely on the coil spring and rebound dampening to control the ride.
I probably made matters worse but I'd be changing fork oil before the springs. Just changing the springs without changinf fork oil is like taking a shower and putting on dirty underwear.
