Can I replace the oil in the forks without pulling them apart?

[78550Detroit]

I bought a 78 GS550 last summer which I have been working on. I had a 79 gs 550E that a friend gave to me which I have been using as a parts bike since the carbs were missing on it. I had found the 78 on craigslist for $400.00. The guy I bought it off of said that the forks needed some attention. I have taken a few rides around the neighborhood and it seems to ride good but the front tire is somewhat dry rotted on the sidewalls. I am going to replace that soon. I don't have my cycle endorsement yet so for now I am just fixing the bike to get it road ready for when I do get my cycle endorsement.I don't know if that was the reason the guy said that the forks needed to be serviced cause when i get up to around 40 or 50 the front does seem to shake a little. Also when parked if I push up and down on the forks they sound kind of squishey like if you were walking with water in your tennis shoes. Should I replace the seals and put new oil in or is there a way I can just drain the old oil and put new oil in with out taking the forks apart? I am use to working on cars this is the first street bike I have worked on and have been using the parts bike for reference before I work on the 78.

[Suzuki mad]

Some of the GS's have a small philips/cross headed screw low down by the brake caliper which should be to drain oil out. Mostly these seize into the aluminium legs. The easiest way to drain the oil is to remove the legs and remove the top plug and tip them up into a pot/container, pumping the fork leg. Then let it stand to allow the remaining fluid drain away.

Beware the main spring will fall out during this process.

DO ONE LEG AT A TIME.

Suzuki mad

1981 GS1000ET
1983 GS(X)1100ESD
2002 GSF1200K1

[Steve]

Like SuzukiMad said, there is a drain screw at the bottom. If you can get that out, yes, you can do it without pulling the forks.

Do you have air caps on the tops of the fork tubes? If you do, it is much easier. Open the air caps before removing the drain screw. This does two things. 1) it allows the fluid (that is left*) in the fork tube to flow freely because it can breathe on top, and 2) prevents nasty oil stains on the far wall in case you forgot to release the pressure in the forks. 8-[
Drain the fluid, pump the forks to get the last bit of oil out. Install the drain screws, put some oil in there, just a couple of ounces in each leg will do, pump the forks to work the fresh oil through all the orifices, then drain that. Fill with the proper amount of the recommended weight fork oil. Install the top caps and enjoy the 'new' ride.

Having said all that, you would really miss out on the opportunity to inspect the bushings inside the fork tubes and to measure the spring length. If you have been using air to help support the front of the bike, you might also want to consider upgrading to Progressive springs and using NO air.









* I say that because if your seals have been leaking, you may not have much fluid in there to start with.

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[tconroy]

Make sure your seals are good and get a manaul so you can do it right.You need to put a certain amount in each fork or you can blow a seal.Go by the book.If your going thru the trouble of taking your forks off then i would go ahead and replace the seals.If it has been sitting very long then you probably nee to do it anyway.Pull your boot duct cover and see if there is oil sitting in there.If so your seals are leaking .

[78550Detroit]

Thanks for the help and advice

I drained the forks on the 79 parts bike today and pulled them off that bike just to see what would be involved in the process. Looking at the forks on the 78 which is the one I am working on the appear to be the same style forks. The drain screws came off easy on the parts bike and so did the top air caps. I noticed that there are two different springs in there a short one at the top then another long one. I did not take them apart fully for further inspection yet.The only thing that I saw that might be a problem is taking off the top air caps with the handle bar on. I did losen the bolts on the collar so I could slide the forks off the parts bike , after I had already removed the handle bar .I went up to rosenau powersports today and they have the clymer book for that series of bike. Is clymer a good manual? Like I said I am use to working on cars more then bikes and I usually either use Haynes or Chiltons manuals.

[Commodus]

For what it's worth, it's been my experience that changing the oil without disassembly is pointless, even when those little screws are serviceable - the new oil will get contaminated immediately.

I recommend taking them apart and flushing them thoroughly with solvent.

[Steve]

I agree that removal and disassembly is the best, but the original question was whether is was possible to avoid it.

Clymer manual is acceptable. Best will always be the factory manual, but many of us use the Clymer.

Two springs in each fork leg are standard on some bikes. That was an early attempt at a progressive-rate spring. The smaller one is usually the lighter-weight spring, it will handle the smaller bumps on the road. When it bottoms out, the longer spring, with a heavier spring rate, takes over.


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[bonanzadave]

I drained the forks on the 79 parts bike today and pulled them off that bike just to see what would be involved in the process. Looking at the forks on the 78 which is the one I am working on the appear to be the same style forks. The drain screws came off easy on the parts bike and so did the top air caps. I noticed that there are two different springs in there a short one at the top then another long one. I did not take them apart fully for further inspection yet.The only thing that I saw that might be a problem is taking off the top air caps with the handle bar on. I did losen the bolts on the collar so I could slide the forks off the parts bike , after I had already removed the handle bar .I went up to rosenau powersports today and they have the clymer book for that series of bike. Is clymer a good manual? Like I said I am use to working on cars more then bikes and I usually either use Haynes or Chiltons manuals.

Make sure your on more than just the center stand when you take off the fork caps. If not the forks will colapse and the bike will fall over.