front fork oil change

[scottiedoug 126]

changing the front fork oil on my NC750X-DCT 2015 model. Before you start make sure you have enought fork oil 10w. The usual things to come off. Take brake pads out first as it is easier then the wheel. Now the mudguard. before you slacken the fork legs slacken the fork alloy caps not off as there is a wee bit of spring tension. Now the top allan key clamp and the bottom bolt slide fork out. good time to polish the chrome legs. wrap fork leg with thick rag and gently clamp in vice and unscrew the alloy cap keep a little downward pressure till it feels free. cap off spacer out then washer. compress till you can get the spring and take out it will drip fork oil so have rag handy to dry . At this point you will now that used fork oil stinks Lol. 

Note the sping had tight coil at bottom. I drained oil pumping the fork leg to get oil out and  into a container to check how much was in the leg a tad over 500ml. but I also measured with the fork leg fully down it was 104mm from top to oil.

Do the same with the other leg.  Fresh 10w fork oil poured in till 104mm with leg fully compressed and no spring in. pump the fork leg to get the oil into the workings and when it is settled check the oil to top  with leg fully compressed (no spring) is 104mm. Pull up fork leg and keep it fully extended put spring in tight coil bottom washer then spacer, be carefull when screwing the alloy cap in do not cross thread it , it should be easy by hand till the rubber O ring bites. same with other leg. I coated the fork chrome with a light film of greaseslid into place and as I had lowered my rear suspension by 40mm,  the front forks are protruding through 10mm to compensate. mudguard back on, wheel  and brake caliper. thats the fork oil changed.

 

[trisaki 2,029]

See how you get on with the 104 air gap , a few of us have used 140 air gap and seems a lot less harsh over the bumps 

[skorpion 945]

Yes I also think the Honda fork oil height is a misprint,

 

102 mm for the S,  I think should be 120 mm.

104 mm for the X  I think should be 140 mm,  due to the longer stroke of these forks.

 

The later forks SDBV from 2016 is 180 mm for the X model.

 

To be sure check with a Honda dealer.

[trisaki 2,029]

I'm very happy with 140 , might have gone a little light with 5grade oil , next change may go slightly thicker  ,say 7.5 or maybe 10 , but at present it's very comfy 

[embee 7,288]

I use Fuchs/Silkolene "Maintain" RSF 7.5W oil, which actually has a viscosity much like many commercial 10W oils, and set it to 140mm in my 700 Integra, but I do have emulators in there so a slightly different animal.

I visited K-tech suspension in Leicestershire to get some fork springs for it, and when discussing the bike they suggested setting the level at 140mm and see what I thought. 

 

The principal effect of the oil level is how rapidly the apparent stiffness of the air-spring increases as you compress the fork leg. The air gap above the oil acts as a spring, and the smaller the amount of air the greater the effect of compressing it a fixed amount.

 

Someone (I forget who) on here opened up the restrictor holes in the damper rods from the std 4.5mm up to 5mm and reported good results. 0.5mm increase doesn't sound much but because of the relationship between pressure difference and flow rate through an orifice, it makes a substantial difference, and remember that you can easily take more metal out, tricky to put it back.

[Defender 3,837]

As usual, there's some really good and useful information above, this forum comes up trumps again .

I STILL have to do my forks, but as it looks as though I'll be having some 'down time' at home shortly, it seem a good time to do it?

[Ozzieflyer 15]

Forks have Honda 10w in there now.

If I change to Motul 10w do I have to take forks apart and clean before putting in new oil, as it is different brand?

cheers,

oz

[jeremyr62 2,545]

8 hours ago, Ozzieflyer said:

Forks have Honda 10w in there now.

If I change to Motul 10w do I have to take forks apart and clean before putting in new oil, as it is different brand?

cheers,

oz

Nope, just invert them and let them hang for a while. The old stuff will drain out.

[Ozzieflyer 15]

On 15/08/2022 at 17:10, jeremyr62 said:

Nope, just invert them and let them hang for a while. The old stuff will drain out.

Thanks for your reply. 
I figured it should be ok, but just wanted to check what others have done. 
cheers.