2015 Street Glide FLHXS Fork Oil requirements

[aussie123]

Rebuilding above bike Stock forks , (Harley rebuild kit no 91700025A.

Having some confusion regarding fork oil requirements...
Manual says , pour in 24oz,(710ml).. Pump fork 10 times , then check from top of tube, so there is 3.74in,, 95mm,(air gap), from top of tube to oil level ... Remove or top up fork oil to get the 95mm air gap....

The confusion I am having is, some info I am reading on the internet say the air gap is 110mm , others say 120mm...Less oil, bigger air gap... At the end of the day the air gap measurement ,(top of tube to oil level ), is the critical measurement.

I know I am double guessing the manual , but there is a couple of discrepancies in the manual, one being the 2015 Touring manual has the parts diagram of the front forks showing the older forks with the older axel holder, (two bolts),  instead of the one screw, (no axel holder)..
As a side note,, the most oil I got out of either forks was max 600ml , (say 650ml), because of oil still in parts etc.... No were near the 710ml, (24oz), that is originally asked for.... This is the first fork oil change , and no leaks ...

Hoping experience minds here may dispel my confusion regarding air gap measurement... Cheers...

[smoserx1]

IMO its not that critical.  The head space above the oil level simply acts somewhat like an "air spring."  I am betting if you went 95, 110 or even 120 mm you would not notice astronomical differences and any of the values are plenty enough to keep your forks lubricated.  Mine specifies an amount (somewhere between 8.5 and 10 oz) or similar (I can't even remember the exact values).  I just buy a 16oz container and put half in each leg.  Been doing it like that for 21 years on the same old FLHT.

[Pirsch Fire Wagon]

Rebuilding above bike Stock forks , (Harley rebuild kit no 91700025A.

Having some confusion regarding fork oil requirements...
Manual says , pour in 24oz,(710ml).. Pump fork 10 times , then check from top of tube, so there is 3.74in,, 95mm,(air gap), from top of tube to oil level ... Remove or top up fork oil to get the 95mm air gap....

The confusion I am having is, some info I am reading on the internet say the air gap is 110mm , others say 120mm...Less oil, bigger air gap... At the end of the day the air gap measurement ,(top of tube to oil level ), is the critical measurement.

I know I am double guessing the manual , but there is a couple of discrepancies in the manual, one being the 2015 Touring manual has the parts diagram of the front forks showing the older forks with the older axel holder, (two bolts),  instead of the one screw, (no axel holder)..
As a side note,, the most oil I got out of either forks was max 600ml , (say 650ml), because of oil still in parts etc.... No were near the 710ml, (24oz), that is originally asked for.... This is the first fork oil change , and no leaks ...

Hoping experience minds here may dispel my confusion regarding air gap measurement... Cheers...

I would stick with the Factory Service Manual. Engineered specifications are design criteria for specific operation. Increase/decrease the Air Gap may, or may not affect the performance under maximums. I have overfilled by mistake and it rode horrible. Corrected the fluid level and it was back to normal. I will say H-D tends to have more dive than others. But, nonetheless, like it or not, that's the engineering design.

Personally, I don't mess with Suspension, Handling, and Braking System limitations. All three can kill you.

[mkd]

aussie123.  i have replaced my 05 electraglide fork oil myself at 60,000 miles after the dealer did the fork oil at 20,000 and at 40,000 miles. my experience is that the dealership put in S E heavy both times so that is the oil i bought when i serviced the front forks myself. What i found out is the dealership fork oil change was approx 20-25% lower in capacity than the spec fluid capacity. when i did the same service and made sure the oil level when done was the correct amount in ounces the front end was way too stiff for my liking. i am guessing the less air at the top of forks the stiffer the fork action is? when the dealership did the oil fill to the lower spec the bike front end was not so harsh and stiff, same oil when i did the oil change and did not ride the same. i ended up draining the front fork oil out, contacting belray fluids, and got viscosity charts and blend charts to custom blend two oil weights to mid weight fork oil between stock and the S E heavy. very precise blending and notes allowed me to modify the fork dampening to whatever was my liking.

[boggart]

My 14' (same forks) manual also states 95MM for measurement.  This is 22 ounces, which jives with the "put 24 oz in, then use the tool to set" in the manual.  I can tell you from experience, it rides smoother with 22oz in the forks than it does with 24.  I recommend following the manual at 95mm.  Just rebuilt my forks last weekend.

[aussie123]

Thanks for your replies,,,
Poured in 24oz, (half at a time, or oil will spill out ),,, Pumped fork tube... Used Mitivac with 95mm tube marked and sucked out excess oil to manual recommended air gap , (I did'nt measure excess oil , but at a guess it was approx 1-1.5 oz)......
So after complete fork breakdown, (not just oil change), it is close enough to 22oz to get the 95mm air gap...

I decided on 15w fork oil. Well be interesting if any major improvements in ride , handling etc, with stock forks,,,, when it stops raining here...

TIP.... Screwing on the fork cap under spring pressure... It can be a PITA...
Temporarily remove top sleeve,
Get fork cap, and start to screw on fork cap,,,,, Identify where fork cap starts to take on threads,,,,, mark a line down fork cap and down top of tube,,,,, Reinstall top sleeve ,,,,, Push fork cap down, (with whatever tool you have),,, Line up marks ,,,,, Heave , curse and swear,,,,,,, Screw fork cap on ......

You will find this easier than not knowing where the fork cap will start to take on threads.....  Cheers...   

[smoserx1]

TIP.... Screwing on the fork cap under spring pressure... It can be a PITA...

Yes it can, especially with stiff springs or lots of preload.  This is how I did mine:
[attach=0]
Compress it till the threads meet then rotate the fork tube to get the threads started.  Or, use a helper, one to press down and the other to rotate the tube.  Lots easier than trying to both press and rotate just the cap bolt.  Glad you got them back together.