Fork oil replacemen.

[Shane]

Hi Can someone tell me how to replace the fork oil on the st1100 and when does it need to be replaced. the manual does not seem to give me clear intructions although i am no mechanic.

[Brock]

As far as I know, its not one of those regular items. The oil is replaced when work is done on the springs, or if you want to try a heavier oil to change the damping rate. (Thicker oil slower/better damping)

[saaz]

Every few years is a good idea, as it does get dark and horrible.

The proper way to do it is to drain the oil, remove the springs, rinse the forks out, collapse the forks and put in new oil up to the specified oil level.  The fork that has the anti-dive on it (right on standard models, left on later ABS) can be a pain to do as the spring has to be compressed to fit under a collar.

A shortcut way is to drain the oil in each fork into a measuring container, and put the same amount of new oil back in.

[Bikebear]

To drain the forks (at least on the '99 model I have) the forks have to be removed from the bike and the oil tipped out the top.  I have planned to do mine since I want to check everything out and maybe up the viscosity a litle since I am 2XL size.

I guess when I do it I should take photos (or maybe get the missus to)and do a write up.

[saaz]

I forgot that the 96 on ABS models don't have drain screws in the forks, so you have to remove them.  I have never worked on one of them.

And should also mention that anyone with a police version, the correct oil level (and springs if you are replacing them) is the same as the pre-96 ABS models, not the same as the standard civilian models.  The Honda police supplement has the correct specifications. The oil weight in the police model is 10W equivalent.

[Abe]

Just changed the fork oil in my 94 Non abs, out of bike (have photo's and will write up)  However, oil was black and smelly.
Unknown when oil was lasted changed.  Front end handling on the RTE to Rylstone was very ordinary to say the least when cornering in the wet on the Putty Rd.

Noted that the rebound on both original forks where different, once removed from the bike:-

Right fork (O/S) was very soft hitting bottom, and a very slow rebound,
Left fork (N/S) (anti dive) was not as slow.

Forks drained over night, washed out with petrol and dried.

Left fork contained 400ml of oil - original spec's say oil amount is 435ml - replaced to 435ml Castrol 10W

Right fork contained 350ml of oil - original spec's say oil amount is 385ml - replaced to 410ml Castrol 10W

Reason being for the extra oil in right fork was to create the same/similar rebound time in both forks.  I have 105mm of fork travel on each fork, when I push them down under my body weight (76kgs).
My PC is in getting fixed so I'm using a laptop without my bookmarks, BUT, I found a UTube video on tuning the forks to rebound the same by adding more or less oil, which I have done.  I think is was from Dave Moss of www.openthethrottle.com  ???

So, I'm going to be putting it all back together over the next couple of days between shifts, so if anyone has any advise, please let me know.

Cheers
Dave

[saaz]

Dave, you will never be able to get the two forks to act exactly the same. The RHS has a damper cartridge that provides both compression and rebound damping pretty consistently. The shims in it can be changed to fine tune it, but best left alone. The LHS fork has a damper rod that does not provide consistent compression and rebound damping, as the holes in the damper rod control compression, and the weight of the fork oil does some work to provide rebound damping (Honds used this system as a cheap way to put on anti dive).

Some have played around with using different weight oils in each fork (say 10W in the right, 15W in the left) as a way to get it to feel better.  Just having new fork oil at the right quantity will probably do what you want.  The oil level when fully compressed with no springs in is the proper way to set it up, then if you vary it you know how much the oil level has changed.

A different oil level will affect the spring rate, as a higher oil level means less air space, so it helps the spring feel stiffer the more it compresses.  My old bike had air forks, so it was easy to play around with different air pressures and fork oil levels.

[alans1100]

Unknown when oil was lasted changed. 

Probably the last time the fork seals were done ......if ever.

That's when I change my oil. Mine is due since the RH seal has just started to weep.........but I'm upgrading to progressive springs at the same time.

[Abe]

On the Castrol 10W container states every 10,000 kms and when I searched the "web" some were saying everytime you change your front tyre, change your fork oil to retain optimum performance.

Cheers
Dave

[Bikebear]

Hmmm..  can't see meself pulling the whole front end out of the bike everytime I replace the front tyre

[alans1100]

On the Castrol 10W container states every 10,000 kms and when I searched the "web" some were saying everytime you change your front tyre, change your fork oil to retain optimum performance.

Cheers
Dave

I tend to go with The Honda maintenance schedule. It doesn't appear to be there so not a big issue it seems. Possibly meaning the oil if it's any good should last between for fork seal replacement.

I had just had a look in the Honda common service manual and it says to use ATF (auto trans fliud) in the forks but that's something I get done professionally; so I learnt something new today.  No hint of fork service interval in there either.

[alans1100]

Hmmm..  can't see meself pulling the whole front end out of the bike everytime I replace the front tyre

Big enough hassle removing the calipers last year, never mind the forks!!!!...........but that was 'cause it was the first time I removed the front wheel myself in six years.