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post #1 of 6 (permalink) Old 10-17-2006, 10:22 AM Thread Starter
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Hello all, I'm trying to figure out my maintenance for next winter and I'd like to change the fork oil, is it necessary to remove the forks or is there a way to get the old oil out without removing the forks??? Also what weight of oil is used by most? Most of my riding is 2 up I'm 200lbs and my wife is 100lbs. Also should I change the fork seals? They are not leaking butI'm wondering if that would be good preventative maintenance???
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post #2 of 6 (permalink) Old 10-17-2006, 12:27 PM
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There's a "damping cylinder securing bolt" on the bottom of each fork. Maybe someone here can tell us what happens when you remove it. The manual says when you remove it you should replace its copper washer - that indicates to me that it is a fluid seal.

I don't know about your budget but you may want to replace the stock springs with variable rate springs, e.g. from Hyperpro. They're a few hundred bucks (US). Hyperpro would also advise you on what weight oil to use based on your weight.

Good luck.
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post #3 of 6 (permalink) Old 10-17-2006, 02:07 PM
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You must remove the forks from the bike.

I just did this last weekend, and here's how. Forgive me if this is old news. BTW, it is a good idea to do this every 12,000 miles/2years.

Remove both sections of the fender, and remove the brake calipers. Hang each caliper from the upper tree with a straightened wire coat hanger.
Remove the front wheel. (If you haven't already, go to the hardware store and buy a bolt with a 3/4" (19mm) head, and two nuts. Jam the two nuts on the bolt, and you have an axle wrench.)
Start with one leg. Loosen the cap with a 17mm wrench or socket, then loosen the tree and handlebar pinch bolts. Remove the fork leg, then CAREFULLY unscrew the cap. You get no bonus points for putting a dent in your ceiling (or face) when the cap comes free. Dump the old nasty fluid in a suitable container, pumping the leg gently; and then rinse the tube out with clean mineral spirits. Set aside to drain completely.

NOTE: I'd look at the fork seals (not the dust covers) and see if they look like they are deteriorated. I doubt they are. If they do require replacement, you will need to tear the legs down. Although there isn't much to it, I'd get the service manual. You will want the illustrations. An air impact wrench is the hot tip for removing and reinstalling the damper rod bolt (the one in the bottom of the tube, with the copper washer.)

The service manual says the capacity of the tube (dry) is 459cc. The factory fill is 8 weight, which is not available around here. I used Suzuki 10 weight. $4 per 16oz. bottle.

With the tube compressed (no spring), you fill the tube to 145mm from the top. Extend the tube, insert the spring (which you cleaned), and then put the cap back on. I had a buddy helping, so we put the fork leg on a couple of newspapers on the floor. He pressed the cap down flat against the tube, whereupon I turned the tube. Worked great!

Wipe the trees clean, and reinsert the tube. The top of the cap should be flush with the surface of the handlebar mount. Tighten the pinch bolts to 40nm (30ft/lb). Tighten the cap until it stops turning.

Repeat for the other tube. Reassemble all the hangers-on. Make sure you attach the speedo drive the way it came off (drive teeth engaged, and drive cable tending straight back).

Another tip is to use a big flat screwdriver to collapse the brake calipers. Do this with the caliper as close to the ground as you can, starting with the left hand caliper. If there was a bubble in the line, there won't be when you do this. You can also take the opportunity to syringe the old fluid out of the reservoir and replace it. Be sure you pump up the brakes before you take the bike out for a ride.

I am 205lbs, and my front suspension is too soft, but I like the performance of the 10 weight oil. I'm probably going to go with RaceTech ( springs, when I get the money.

I apologize for the excessive verbiage. Hope this helps!


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post #4 of 6 (permalink) Old 10-17-2006, 02:29 PM
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You can drain the oil without taking them out of the triple clamp but I don't recommend it. You can pump it out using a Mity-Vac for example. You can also drain it by removing the damper screws as mentioned above. What I recommend is to do most of the procedure that pushrOd explained and get new seals and bushings. Flush the fork out with something like kerosene or some super cheap 30wt. I'll bet my last paycheck you will find a lot of crud in there. Unless you are a real twistie maniac, I would highly recommend getting Hyperpro variable rate springs. I have them and RT emulators plus have installed RT springs and emulators on a previous bike. For 90% of the guys out there, the Hyperpro's will do the job and will be a big improvement over the stock forks. I won't recommend any particular fork oil. Hyperpro recommends 5wt, RT 15wt, stock is 8wt and I run 10wt (235lbs plus 50lbs of junk in my bags). It depends on who you talk to and how you ride. One thing you can do is adjust the oil level because stock has a lot of air and RT uses a lot more oil so by varying the amount of oil you can adjust ride AND you can do that by just pulling the caps on the forks to add and delete oil.

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post #5 of 6 (permalink) Old 10-17-2006, 03:18 PM
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All good advise from above. I would also recommend 'doing it the right way' and remove the forks. It's a winter project so you don't really need to cut any corners because of time.

I would only make 'other' suggestions for you to consider.

The Race Tech springs are a great upgrade to help cure the severe brake dive these bikes have with the stock setup. They have a calculator to figure which spring you should use based on your weight. I would recommend if you ride solo most of the time to use one spring softer if you like a cushy ride. Mine is not harsh by any means, but it is firm. I think they lean toward the firm side. Thats just MY opinion though.

My forks felt better if I put about 50cc more oil in each fork leg than recommended. It felt like the first inch of travel had an air pocket (the best way I can explain it) when you compressed the forks. This went away with the extra oil. The extra oil also helps with the brake dive as these is less air to compress in the fork tubes. I used 10 weight oil so someone who has used 15w may be able to tell you if this is necessary with the heavier oil.

For flushing the forks I would use the mineral spirits (or diesel fuel) or as I did plain denatured alcohol. The Alcohol would leave things VERY dry (Home centers carry it) so, I then flushed mine again with ATF and I would recommend this over using motor oil for a couple of reasons. Motor oil is not a hydraulic oil. ATF is. ATF can and is used as fork oil. (approx 5w) It is highly detergent so it will help remove any sludge that may be in the fork. You could even use it in place of any of the previously mentioned solvents if you are worried about them being a bit harsh.

Don't worry to much about the springs sending the cap across the room, they're not under that much pre-load. Just make sure you have a grip on them as you get near the last thread. They will only thread out about 3/8" before they are free.
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post #6 of 6 (permalink) Old 10-17-2006, 04:17 PM
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I too have done the process the easy way and the "right" way, take your pick. I don't think it makes that big of a difference.

I chimed in because I have 15wt in there now and think that it is alittle too stiff. I am also running Progressive springs and NO emulators. I ride pretty agressively and have considered the Gold Valves but really have not heard anyone say that they are real worth the money.

I think next month I am going to back down to 10wt and increase the volume a little.
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