Easy Fork Oil Change On Baggers

Fork oil weights... Fork Oil Weights - Harley Davidson Community

If you ever tried a service on the front AIR FORKS on a bagger , you can appreciate this tip......
This does not work on the newer cartridge forks...Sorry!
Cartridge forks started in '02 on the left side of the touring models with fairings only. FLHT,
FLHTPI, Ultras, etc. Starting with the 06 bikes, the cartridge forks have been replaced with the normal oil type lower legs on both sides.

Best results with bike up on a lift and the suspension unloaded.
Pick up a vacuum pump either hand or electric , a mity vac hand pump pictured below will work too.( I used a vacuum pump from air conditioning service) but an old refridge motor will work just as well too if you use the suction side and a hose adapted to the air fill valve on the front end.
My A/C pump can draw 24 lbs of vacuum and the hand pump draws 26 lbs of vacuum.

What I found that helps in those stubborn cases with the thicker oil is to draw the vacuum on the leg while the front wheel is still on the ground (assuming you have the bike on a lift) and after pulling the vacuum to the max on the leg you are working on, jack the bike wheel just off the ground just prior to adding the oil. This extends the lower leg and increases the vacuum in the leg to help pull the heavier oil into the leg.
Stock weights usually don't have a problem, it's just the heavier weights that do.



It goes like this for the air assist front ends...

Remove the air from the forks first, remove the schrader valve from the air fill valve with a valve core remover , available from any parts store. Support the bike on a lift preferably and drain the oil out of one side at a time. Now here's where it gets tricky. I made an adapter to screw into the drain hole in the fork from the proper thread bolt (it's metric)( FXRT/FXRD= 4 MM X 0.7 pitch X 20 MM long) (FLT/FLTC/FLHT/FLHR/FLHTC= 8 MM X 1.25 pitch X 30 MM Long) and drilled through the center in a drill press to make it hollow , then I cut off the threaded hollow bolt about 1 1/2 inches long just below the head so that there is a smoothe end for the hose to attach to.. This bolt gets a piece of clear tubing attached to it (so you can see the oil) about 6" - 12' long. The shorter working length here will help you in the end result for drawing in more oil. This bolt gets threaded into the drain hole to be used to suck the premeasured oil for your application into the fork when you apply the vacuum to the air fill valve. Only apply enough vacuum to keep the oil in while you replace the drain screw with a new washer installed of course.This gets real easy if you have an extra set of hands around to pump while you do the rest.

Repeat this on the other side and you're done.
No tins have to come off and it is probably the easiest service you will ever do on a Harley. It usually takes me about 15-20 minutes or so once everything is set up and ready to go. Sure is quicker than removing all those tins or fairings.

To drill the bolt hollow for this , I bolted it into a piece of steel plating so it would remain perpendicular in the drill press using 2 nuts, one on top and one under the plate.

The green tubing is available from EMS services and has the adapter end built in for connection to an oxygen tank which fits very nicely over the 1/4" tubing in the tool.. It also has ridges on the inside of the tubing so it can't collapse under vacuum.

For the NON air assisted forks...

You can also use a vacuum pump to draw a vacuum from the drain hole (with the large tube) once it has drained if you make up a tool like I made shown below. The green hose on the left in the pic is substituted for the larger vacuum hose once the oil is ready to be siphoned in. The large hose is used for the vacuum process in the fork tube.
All parts are available in most hardware stores and it works well so nothing other than the drain screw has to come out. If you are using a heavier than normal oil, it may not draw in all the oil this way, that's the only drawback with doing it this way. Standard oils work fine. (5-10 wt). I used Screamin Eagle heavy (15 wt) and it pulled all but about 1/2 ounce into the fork. Then again , I run an additional 1/2 ounce over the factory specs in each fork leg for better handling.

The way it works is this..

You drain one leg at a time and when it is drained you attach the connector to the drain hole. You then draw as much vacuum as your pump will go and after that, you close the petcock so you can change the hose that was attached to the pump to a shorter one for drawing in the new oil. After the connection is made, you re open the petcock and in goes the oil. After it is all in, you work quickly and remove the connector and reinstall the drain screw. You only loose a drop of oil doing this and is nothing to be concerned about.

Repeat this on the other side and you're done.
Again, No tins have to come off and it is probably the easiest service you will ever do on a Harley. It usually takes me about 15-20 minutes or so once everything is set up and ready to go. Sure is quicker than removing all those tins or fairings.

Here's the tool for this and what it consists of.
The brake tubing (hard line in pics) along with the compression fittings is 1/4" and uses a larger (maybe 3/8") petcock with reducers to the 1/4" fittings. The clear tubing is 3/8" ID to fit over the ¼" OD brake tubing and a couple of mini clamps with an "O" ring on the end to seal it against the fork.