What oil and amount of oil suits the 1050 forks

Fork oil is the same as hydraulic pump oil. Depending on your preference choose a light weight oil, 5-15 will give a soft ride. As the weight numbers go up the comfort level goes down. However, the heavier weight oil provides better handling. A bit of experimentation will varying weights should be considered for the optimal combination of ride comfort and handling. One final note. Always. Purchase a non-detergent oil

The fork oil does not have anything to do with the kind of engine do you have, 2t or 4t. Doesn't matter.
You need to replace the fork oil, you need to know the year of the fork. means, you need to know if it's a bladder or non bladder fork.
oil height of the bladder fork is approx. 70mm, non bladder forks run about 100mm oil level.
oil amount is about 530-600cc per leg

310ml all the best.

If you are saying that your front suspension is too soft, you can change the fork oil in the front forks to a heavier viscosity. I think Harley recommends Type E fork oil. I've found that PJB 30 wt. fork oil works best for me.

Since I'm not familiar with the newer forks, I'll have to recommend that you ask the dealer how to drain and refill the forks and how much oil to put back in them. There are usually two amounts of oil to put in the forks. One amount is a "dry" amount to add when you disassemble the forks and then refill them. The "wet" amount is for when you simply drain the forks and then refill them. Naturally, the "wet" amount will be less than the "dry" amount.

Sorry I couldn't give you more information but my expertise is the earlier model Harley bikes.

Good Luck
Steve

Depending on the G S 450 model you have these forks take between 5.1 to 6.4 Imp. oz. the best way is to drain the fork oil into a measuring cup and then replace that same amount + a bit . Any fork oil will do the job you can even get a synthetic one now. Good Luck

If you want to change your fork oil, best way is to drain a fork leg into a container, and measure the amount that comes out. You can make your forks softer or harder by varying the amount of oil.

check the starter relay next to the battery

Change your fork oil to something more suited to your driving style. Those forks may be feeling tired, but they works nearly as hard as your valves. The oil has most likely broken down and needs replacement anyway. Do some shopping and ask the experts what is best for your cruising preferences, If you need a stiffer or softer ride try inserting a new set of springs. Remember coil windings as well as fork oil determine the cushion in your ride.

The forks hold 286ml or 9.67 US OZ of oil, best would be to use hydraulic oil.
Good Luck.

there is no set amount required. different amounts of oil make different suspension set ups. check with your local dearler and see what will be best suited for yourneeds and body weight. also you need to buy the right weight of fork seal oil to get the right ride.