redelk
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posted June 11, 2002 11:44 AM
BLADDER QUESTION
The OEM specs for the nitrogen in the shock is 142 PSI. In a "total rebuild", with includes replacing the nitrogen bladder, RaceTech specs it at 200 PSI. On my 7R's shock it was around 235 PSI. Does anyone think taking the OEM bladder up to 200 PSI would create any problems?
I personally don't think there will be any problem from a capacity or pressure aspect. One of the reasons I think RaceTech replaces the bladder is to get rid of the valve that requires a "needle" in favor of the one with a "tire" valve.
Opinions?
   
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Ballisticzx12r
Zone Head
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Posts: 940
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posted June 11, 2002 11:51 AM
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Bart
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redelk
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posted June 11, 2002 01:34 PM
Okay, just for you, Bart...
I'll go though it R E A L S L O W...
If you'll re-read the first sentence, "The OEM specs for the nitrogen in the shock is 142 PSI.", you can see that I'm talking about the rear shock.
If you look closely at your shock, you'll see a small "canister" that is attached, at an upward angle, to the top of the shock. This is where the nitrogen is stored in what is called a "bladder".
At the end of this canister will be a silver cap with a "hump" in the middle. In the case of most Kawasaki shocks, if you remove this cap, what appears to be a tire valve stem will be exposed. You've probably seen them on aftermarket shocks. This valve is how they bleed and recharge the shock with nitrogen.
Sadly, Kawasaki doesn't tell you that can be done with their OEM shocks. To make matters worse, on the 12R, Kawasaki chose to use a "needle" type valve instead of one with a core (like a tire valve). Most OEM and aftermarket manufacturers have quit using the "needle" type. Why KHI chose this type of valve for the 12R, beats me.
Anyway, even though nitrogen has the capability of maintaining a constant pressure under a wide temp range, it doesn't last forever. Buying a new aftermarket shock would be nice, but really isn't within my meager budget. For the most part, the majority of the shock's internal parts (seals, valves, oil, etc.), have a lifespan that far exceeds that of the nitrogen.
So, after close to 33K miles, recharging the nitrogen is a VERY CHEAP way to bring one's rear shock back up to snuff. Recharging a rear shock usually runs from $10 to $15. This is probably due to the fact th MX riders do it so often. Most shops have a nitrogen tank in back, but most of them do not have the needle attachment.
I convinced my dealer to bring one in (a $28 Motion Pro Needle Kit from Parts Unlimited) and have them ship it second day air. That means that it should be in on Thursday and my RaceTech fork springs (1.0 kg/mm) should be in at that time.
Is it as good as sending everything off or buying new forks and shock? Of course not. But for a total investment of around $100, I will not only have a suspension that is as good as new, it will be even better. That's cheaper then just the shipping costs of sending it off. Not to mention less the 1/10 the cost of having the forks redone and getting a new rear shock.
So, unless you want to "loan" me the money (after you get your lap timer) for new stuff, this is about the best I can do for now. Since I'm improving the forks with stiffer springs, I was wondering about the posibility of increasing the pressure of the nitrogen in the shock.
THAT... is why I'm asking the question about the OEM 'bladder". Does that make it any clearer, birthday BOY! 
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slug
Pro
Out in search of my mind...
Posts: 1433
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posted June 11, 2002 07:44 PM
you prolly need to explain KHI to him as well ;P
  
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Y2KZX12R
Needs a job
CompetitionCNC.com
Posts: 3762
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posted June 12, 2002 01:45 AM
Red, I havent been inside the rear shock. I dont know what would work well. But racetech seems to know what works well.
Schrader valve bladder (tire stem type) is a welcome swap. But not needed if cash is short. Your call.
Good luck.
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EastBayDave
Needs a job
Posts: 2245
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posted June 12, 2002 05:34 AM
before you spend the money & time/effort you should give Jim Lindermann a call. He does the suspension for many of the AMA Superbike teams as well as local racers. He was one of the founders of Fox shocks, provided me with a wonderous prototype shock for the GPz series KAW's ("twin-clicker") back in 83', & has various options for forks & shock rebuilding.
He had some surprising things to say about the ZX12R shock, like the "barely usable compression adjuster," & has a fix for this that comes standard with a rebuild / recalibrate. It's about $300 for each end (shock/forks) if memory serves...
www.le-suspension.com
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Enjoy the ride!
02' ZRX1200
00' ZX12R sold
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redelk
Moderator
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posted June 12, 2002 06:36 AM
Thanks guys
Y2K, I seriously thought about swapping bladders since I could score one pretty cheap, but since this will be the only time I do anything to the shock (and my dealer didn't have the bladders in stock), I'll probably just settle with a recharge. By end of next year, my baby will be getting close to 50K miles and it'll be time to put her out to pasture.
EBD, I'd love to go that route but there are three things holding me back...
1. Down Time - It'd be a remote possibility if it was the dead of winter, but it's not. Since every weekend that it's not raining is so damn precious to me, I couldn't stand give one (or more) up while waiting for my suspension parts. In doing all the work myself, I might end up giving up a Saturday ride. To me, that will be painful enough.
2. Money - I have NO DOUBT that it would be worth it. The ballpark price range you mentioned is VERY competitive and I'm sure he does nothing but quality work. It's just that since I've taken over payments on my late brother's car, it's caused a strain on a already tight budget.
A expense of $600 is really rather small for what I'd get in return, but spending around $100 is about the best I can do. Even though I'm just getting the heavier fork springs and the shock recharged, I can't help but believe that there's going to be at least some improvement. In other words, I'm figuring it's better then nothing.
3. Money - It's worth saying again.
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There are only three sports: bullfighting, motor racing, and mountaineering; all the rest are merely games.
-Ernest Hemingway
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EastBayDave
Needs a job
Posts: 2245
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posted June 12, 2002 07:11 AM
Yeah I understand man. Being out of work 2+ years has me down to the bare bones. I really want the high-end Penske, or Ohlins; but that's out of my reach. I tried selling the Ninja, but the best offer I got was $6000! The dealers wouldn't offer me much more; I tried trading on a ZZR1200; but no dice. Considering the extras I have on the bike (Dymags/Akro/etc.), I may as well keep it...
As for LE, you should at least give Jim a call. He spent the time to chat w/me at length about the Ninja's shock. It was quite some time ago now, but I seem to recall him saying "they all leak, I fix that. The compression adjuster is almost non-functional. I fix that on every shock that comes through here."
I talked to one guy who had it done at a local "bike-night" here, & he was very happy with the results. Sure beats the price of a Penske shock & Ohlins forks!  Soon as I have a few spare bux, I'm at least doing the shock. FYI, almost ANY moto-x shop can rebuild the shox/forks. You just need to walk in with the items in hand, & don't tell them it's a streetbike... (I discovered this w/the ZRX1100 shocks, cost $90 for a rebuild of both!) 
____________
Enjoy the ride!
02' ZRX1200
00' ZX12R sold
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