Gents:

I need to replace the seals on my forks and have a couple questions.  Do I need to replace anything else other than the seals?  I read the thread were someone mentioned it was good to have some of the extra washers and so forth.  Also, I would like to have the forks a lot stiffer.  Can someone recommend a good oil to stiffen them up a bit.  I suppose the amount of oil in the clymer's is correct as well.  Thanks for your assistance.  

Best regards,

Dave:

The one fork seal is starting to leak pretty bad so I need to fix those.
Generally speaking, I would prefer to have a stiffer front end.  They bottom out more than I would like; although, that has probably more to do with the condition on the roads.  I don't want to rebuild everything, but it does need some attention so I thought it would be a good opportunity to message it bit.  

Best regards,

The stock spring is progressively wound. In order to achieve the correct amount of preload I would suggest that you set the total sag at 35mm. If you are blowing through that value you will need to add washers between the fork cap and the spacer. This should help improve the first 1/3 of fork travel.

Adding fork oil only effects the last 1/3 of travel. The stock oil height is 75mm from the top of the tube (measured with the spring out, tube at the bottom of the stroke). This is a very high value, you can try to add an additional ounce for a total of 16 oz.

Adding thicker oil (the stock is 15w) effects rebound only and is not a way of stiffening the suspension.

Forks with progressive springs are difficult to properly tune, but sometimes small changes can get you over the line between to soft/harsh and acceptable.

Being an old bike I suppose these will go bad eventually.  Considering I added the 12.25 rear shocks, would the angle change in the front end contribute to the failure as well?

Best regards,

I'll give that seale mate a try sometime today.  I'm not optimistic; although, I'll give it a go.  What kind of oil should I get assuming I will need replace the seals?  I wouldn't mind adding washers just to firm it up as well.   Is this the correct part #?

http://www.partsfish.com/oemparts/a/suz/506b36c1f870022ba8af9e61/front-damper

WASHER
51158-14100

Thanks,

The ID of the fork tube is 33mm and the OEM spacer has an OD of 31.8mm (1.25"). Any washer with an OD of 1.25" will work fine. If you need to add more then 3 or 4 washers...it's probably best to make a new spacer. PVC piping with an OD of 1.25" would work just fine.

Any brand 15w fork oil will work fine as will Dextron ATF. If you are able to resolve the leaking fork by simply removing debris, you won't have to remove the forks from the triple clamps to set the sag or adjust the oil level. If you find that the seals need to be replaced the forks will have to be removed. This is a good opportunity to clean out the old fork oil. You'd be amazed at how dirty it gets.

Make one change at a time. Don't set the sag and add fork oil because if you don't like the result, you won't know which change to reverse. You may find that simply getting the sag correct solves all of your ride/handling issues. If however you are still blowing through the last 1/3 of stroke, then you can start to experiment with the fork oil level. As I mentioned, the LS650 oil is already very high, so just a little additional oil may make a big difference. Keep notes on what you do. This way if the forks need to be serviced in the future, you'll know exactly how much oil to fill the forks. The OEM oil is 441cc's (14.91 oz) resulting in a height of 75mm.

For reference, every well sorted fork I've every worked on has had an oil height of 120 to 130mm. Suzuki has really overfilled the LS650 forks in an effort to hide the extremely poor damping and performance of the chosen progressive rate springs.

Gary_in_NJ wrote on 02/12/15 at 06:31:51:


Which explains the tendency to blow out the seals when you do wheelies.

Quote:

You already have up to 1/2" of preload.  Adding more could get real interesting.

Ok, I just about got the forks torn apart.  I made the tool to that extends to the bottom of the fork with the 24mm head.  I'm waiting for the JB weld to dry before I can split them apart.

I got some spacers to stiffen up the shocks; although, I'm not sure where to put them when I go to reassemble everything.  Can someone offer some insight?  Thanks.  

Best regards,