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KYB Shock Bleeding with a Mountain Dew Bottle

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I just got done replacing the shock oil in my kids YZ125. When I went to put it back together I couldn't get the compression adjuster back in without trapping a pocket of air.:banghead::foul:

I read many post about different methods, like drilling and tapping a bleeder in the shock body, but didn't want to go that route. Submerging the shock in oil would work, but use way too much oil.

I decided to try something else. I cut the top and bottom off of a Mountain Dew bottle and attached it to the shock using duct tape.:lol: Cause we all know that stuff can do anything!:):smirk:

kybairbleed2.jpg

This worked better than I ever thought it would. The higher oil level allowed me to cycle the shock through it's stroke to remove any last air bubble without worrying about drawing air back in or shooting oil all over the place.

Once I was sure I had all of the air out, I submerged the compression adjuster in the oil upside down to let all the air escape then flipped it over and installed it, ensuring virtually no air in the shock.

Only about 200ml of oil was wasted and I probably had about 5-10 minutes to do everything before I noticed some oil starting to work it's way through the duct tape. Not the most technical method, but it worked great for me!!:cheers::ride:

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good idea :lol:

when I serviced my first shock ('83 RM125) I used a tin can which was

bigger than the shock and reassembled the shock in this can full of oil... :)

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I used the same "concept" and after the first experiment with tape with the same result, oil all over, i made a coupling from silicone. No more oil lose and don't have to rush the work :lol:

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I was thinking about this the other day. My idea was to put the adjuster in, and extend the reservoir housing up and the seal head portion so that it was above the shock body and you could over fill it that way.

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a use a similar metod with a little cone bottle over the cadj thread , fixed with american taper,i cut a plastic funnel.

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I would love to see pics of your various ways of doing this:worthy:

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kyb on www.motocrossmarketing.com in italy sell a alloy funnel maked for bleed the shock .have the thread for fix it on shock near 60 euro.but with this tool you can bleed the shock but can t put in the cadj without removing it. i use a big funnel and put the cadj in without remove it

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I was thinking about this the other day. My idea was to put the adjuster in, and extend the reservoir housing up and the seal head portion so that it was above the shock body and you could over fill it that way.

this is the cup I use to extend the shock body

shockbodyring.jpg

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if you drill and tap the seal head assembly you could use the space above to bleed it

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dont you overfill the shock doing it like this? when you do the final bleed thru the comp adjuster,it releases the x-tra oil and air right?

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dont you overfill the shock doing it like this? when you do the final bleed thru the comp adjuster,it releases the x-tra oil and air right?

I don't think it can overfill it. The compression adjuster traps a small amount of air inside of it as you thread it in and I don't know of any other way to get it all out without taking the shock apart.

I tried bleeding it, but when moving the shock through it's stroke I could feel the air and the shock shaft wouldn't fully extend on it's own.

People are using many different methods, this one just seemed to work best for me for a quick oil change. No drilling/tapping, quick, minimal wasted oil, and no mess if your careful!

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if you drill and tap the seal head assembly you could use the space above to bleed it

Or if you replace the seal head use an aftermarket such as All Balls. Comes with a bleed hole.

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I like Dave J's procedure of letting the air through the hi-speed comp bolt. It's very easy and it effectively empties that air pocket. I found a trick to make sure to keep intact the o-ring at the base of the stem in the compression adjuster. While i bleed the shock i will put the stem and o ring in the freezer. When i re-assemble with the frozen stem and o-ring, the o-ring never snags and cut like it used to. I always get the squirt in my face though, too dumb to remember to not look so close...

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the bleed hole isnt the same as what i mean, if you had a bleed screw, the area above the seal head(the end of the shock body) would make a nice little reseviour for the oil to sit, and you could bleed it over and over till no more air comes out.

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if you are not doing a final bleed on the shock,you are still running the risk of overfilling it.i guess time will tell.keep us posted

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you won't overfill a shock by fitting a comp adjuster ? it takes up very little volume ?

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I like Dave J's procedure of letting the air through the hi-speed comp bolt. It's very easy and it effectively empties that air pocket. I found a trick to make sure to keep intact the o-ring at the base of the stem in the compression adjuster. While i bleed the shock i will put the stem and o ring in the freezer. When i re-assemble with the frozen stem and o-ring, the o-ring never snags and cut like it used to. I always get the squirt in my face though, too dumb to remember to not look so close...

Dave's method of disassembling the compression adjuster works exceptionally well. You can find it here:

http://www.thumpertalk.com/forum/showthread.php?t=645284

There are, I think, a couple of keys to it that are worth mentioning.

First is to work through one or two fill and purge cycles with none of the exchange valve parts in place, but with the shock closed by having the adjuster screwed in. The bladder should be charged to around 25 psi to hold the seal head against the lock ring and prevent sucking air past the seal. Work the shock a number of times, release the air pressure, remove the adjuster housing and add more oil if necessary. Repeat this until you are satisfied that you have the air out of the main body and reservoir. I also might note that if you are reusing a bladder that tends to pucker or pleat when deflated, you'll want to retain just enough air to keep it from doing that.

At this point, install the exchange valve assembly (Great tip on freezing it, BTW, I'll try that on the next one), set the adjuster screw in place, and charge the bladder with about 5 psi. Fill the shock to the extent possible and position the adjuster housing, filling the small remaining void with an eye dropper or syringe. You will usually have to thread the adjuster screw into the housing a little way before you can engage the housing threads to the shock body, then alternate between turning the screw and the housing as Dave describes.

Pretty easy, and very effective.

if you are not doing a final bleed on the shock,you are still running the risk of overfilling it.
If the shock is filled for the final time with the rod extended and the bladder expanded with 3-5 psi, the available oil volume is exactly what it should be, and it can't be over filled. If the bladder is not charged with a low pressure, and tends to collapse as mentioned above, then you could possibly overfill it, but it's easy to avoid that.

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The bladder should be charged to around 25 psi to hold the seal head against the lock ring and prevent sucking air past the seal.

:lol:

good point, will do this next time I service a shock...

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A few quick shots from Innovera`s "Duster" compressed gas, also works quite well at shrinking small o-rings and bearings:) Watch your fingers though....:lol:

Spraying while can is upside down works best.

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