BassCliff's Service Manual and Fork Oil Level

[Mith]

I'm all set to fill my forks and replace the seals. I looked up the level needed in the manual from BassCliff's website. It left me confused. It lists the level at 219.6ml. I saw the spring length service limits listed and compared them to mine and mine match the second set of numbers that have an (E-28) next to them. There is a second set of numbers for the fork oil level that says 208ml. This is all on page 454. Should I be filling it to 219.6ml or 208ml? What does the (E-28) represent?

This is a 1981 GS550L which is the X model.

Thanks for your help!
Pete

[Nessism]

A 11 mL different is not important, what is important is that both fork legs are filled to the same level. To check level the springs need to be removed and the forks fully compressed. Dump in the quantity of oil you decide upon (I’d use the lower amount) and then measure with a ruler to see how far up the tube the oil comes. Once you have one fork done, fill the other fork to match the first.

[Mith]

Thanks! I'll get to work on filling them immediately.

Best Regards;
Pete

[Steve]

I just looked at that manual and I am confued, too.

pdf page 566 says Fork Oil capacity 249 ml
pdf page 575 says Fork Oil level 201 mm (7.91")
pdf page 576 says Fork OIl capacity 190 ml
pdf page 586 says Fork Oil level 208 mm (8.19")
pdf page 587 says Fork Oil capacity 249 ml


Yet you say that page 454 (which is pdf page 460) says Fork Oil level 219.6 mm.
However, you need to look at the model listing at the top and note that this is for the standard model, you also mentioned that you have an L. The quotes I have above are for the L model, which has different forks than the standard model.

You also need to note the difference in wording in the specifications. There are measurements for CAPACITY and LEVEL. Capacity is how much oil you should have to put in. Level is how much room there will be above the oil. As an example: If you have completely drained and cleaned the fork tubes so they are DRY (no residual oil in them at all), and you put in 249 ml of oil, then stroke the tubes a few times to make sure there are no air bubbles in any of the damping passages, when you compress the tubes fully, there should be 201 mm of space from the oil to the top of the tube.

Most people feel that it is the level that is more important than quantity. If you don't completely disassemble the forks, there will be a bit of oil left in them. If you simply add the 249 ml of oil, the level will be higher, resulting in a smaller number from the oil level to the top of the tube, so go for the level, just use whatever quantity of oil that it takes to get it there.

The reason that matching oil levels in the fork tubes is important? Air is trapped inside the tubes. (Some bikes have fittings so you can add additional air.) When the forks compress, the air also compresses, adding to the spring rate. If the oil levels are different, the spring rates on the two fork tubes will be different, which can lead to some interesting handling problems.

.

[Mith]

Steve -
I do have the 'L' model bike and I have completely disassembled and cleaned everything. There is no oil or crude in them anymore. I interpretted the terms capacity and level differently then you discribed. It's much more clear now. I'll have to go over those pages you noted and try to figure out how many ml to put in.

Pete