Author Topic: Yet another suspension rebuild  (Read 2552 times)

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Offline batboy

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Yet another suspension rebuild
« on: October 02, 2018, 12:03:01 pm »
In the 3 weeks since I bought my 1988 Concours, I've done the Mean Streak 17" wheel/brake conversion and several other little things. Once I got the bike back on road, I decided to let Connie tell me what she needed next. The bike's suspension is mush and bumps are jarring. The nose dives excessively during braking. In another year or two, I will probably swap in a ZRX front end. So, I don't want to spend a lot of dough right now on the forks. But, I figure it needs more than just changing the fork oil. I have a new Race Tech 1.0 springs and 15w fork oil on order. I also picked up what I need to do an oil refill for the rear shock.


While waiting for parts, I was messing around and decided to check the air pressure. Front and back tires are at 42 psi (that seems a bit high?). Air pressure in the forks and in the rear shock was basically nothing (maybe 1 or 2 psi at best). I don't care about the front forks, I'm putting new springs and fork oil in and eliminating the air valve. I ordered manual preload adjuster fork caps from the later ZG1000 and hope they fit the early models. I know people will tell me I should get the emulator valves too, but that raises the ante a bit more than I like (I might swap in different forks, remember).

I'm very concerned about the rear shock. If the air pressure leaked out years ago, I figure the shock is toast. But, since I'm waiting on parts, I plan to put 25 psi into the rear and check it daily to see if it leaks immediately. If so, I'll replace the shock. if no significant leak, I'll try refilling it with fresh shock fluid (actually I will be using 10w hydraulic jack oil in the shock).

I plan to change the fork springs with the forks left on the bike (the early ZG1000 has drain holes). But, I did want to lower the front a little (maybe 1/2 inch) since I have a low profile rear 17" tire. I know that I need to slide the tube up to do this task. Do you have to loosen the pinch bolts on both upper and lower triple tree clamps? Is there a step by step guide? I looked in the tech pages, but didn't see one for lowering the front.
1988 Kawasaki Concours ZG1000 - Ninja Edition
Bike has the usual accessories and modifications

Offline Pbfoot

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Re: Yet another suspension rebuild
« Reply #1 on: October 02, 2018, 01:51:46 pm »
Yes. You have to loosen the upper and lower triple tree.
If you don't have time to do it right, when do you have time to do it over.                                                                17" wheels, Nissin 4 piston calipers.1kg Sonic Springs.Cartridge Fork Emulators. KB Brace. Galfer brake lines  Free power mod.

Offline works4me

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Re: Yet another suspension rebuild
« Reply #2 on: October 02, 2018, 02:38:17 pm »
And while you’re in there, check your steering head bearings.
Clean, lube and properly set preload.  :great:

Offline batboy

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Re: Yet another suspension rebuild
« Reply #3 on: October 04, 2018, 05:00:11 pm »
Okay, I've loosened the 4 lower triple tree pinch bolts and the 4 upper triple tree pinch bolts, but the forks would not slide up. Before long I have pipe wrenches, big hammer and chisel, and cutting torch out and soon everything is mangled, melted pile of junk. I see there is a pinch bolt on each of the two handlebar risers, which nobody told me about, so presumably that needs to be loosened too.

The middle sentence was a joke.
1988 Kawasaki Concours ZG1000 - Ninja Edition
Bike has the usual accessories and modifications

Offline works4me

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Re: Yet another suspension rebuild
« Reply #4 on: October 04, 2018, 06:08:11 pm »
Yes, also loosen the handlebar pinch bolts.

Offline batboy

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Re: Yet another suspension rebuild
« Reply #5 on: October 04, 2018, 06:26:53 pm »
I removed the handlebars and using little bungee cords, I carefully hung them out of the way with the brake and clutch reservoirs as level as possible. Now that gives my lots of room to work on the forks. I have the bike jacked up and front tire barely suspended. Think I'll first adjust the forks up (lower the front end) and once that's done, I'll replace the springs and refill the fork oil.

Has anyone changed the early air pressure to the later style manual preload adjuster with a bolt? Hope it can be done and if so, a few hints on how you did it would be great.
1988 Kawasaki Concours ZG1000 - Ninja Edition
Bike has the usual accessories and modifications

Offline Daytona_Mike

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Re: Yet another suspension rebuild
« Reply #6 on: October 04, 2018, 06:37:26 pm »
The gold emulators are really a must but if $$$ is an issue then there are  cheapo knock off emulators which should work just fine. I run 1.2 Sonics with emulators and 50w shock oil. the front is just about perfect as it can be  with emulsion tubes.  I think you would be happy with the Sonic and emulators that you  see no need to go to the ZRX front. To be honest I prefer the 18" wheel on the C10. I think it handles better than the 17 inch.
The stock  rear shock is really not worth the  will be time of day. It is just no good no matter what you do to it..
 I know you dont want to hear this but the Progressive 465 is a really good option for that bike. This is a valved shock. ( the stock rear is not)
The other option is a c14 shock. The spring is soft with that  c14 shock   on our c10's but   you are  already running soft front springs so it should be a good match.
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Re: Yet another suspension rebuild
« Reply #7 on: October 04, 2018, 10:10:04 pm »
Does the 86 bike you have, have spacers in the forks?
Do you know if the new springs will be used with spacers?

All of this will be very important if you use the adjustable fork caps.
Reason is; The adjustable caps may be longer than the original so they will add preload.
If they are; You'll need to shorten your spacer to adjust for that extra length.

Why are you wanting to lower the front of your bike?
The change to a 17" rim already lowered the front of the bike..

Ride safe, Ted
« Last Edit: October 05, 2018, 12:04:47 am by connie_rider »
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Offline batboy

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Re: Yet another suspension rebuild
« Reply #8 on: October 04, 2018, 10:38:46 pm »
The bike is a 1988 model year. The springs I took out were 20.25" long and did have a 2" long steel spacer. The new springs came with a piece of PCV to use as a 6" spacer in each fork. The new spring is 14" plus 6" spacer for 20" length almost the same as the stock spring. I assumed I was supposed to use the 2" steel spacer too.

The manual fork adjustor cap from the later C-10s will not work. They do not fit into the tube. I think the early C-10 inside fork tubes cap threads are down lower on the inside of the tube. Anyone with a later C-10 need a fork pre-loader cap? I now have a couple extras now.

I'm having trouble compressing the fork springs enough to put the old caps back on.
« Last Edit: October 05, 2018, 11:48:39 am by batboy »
1988 Kawasaki Concours ZG1000 - Ninja Edition
Bike has the usual accessories and modifications

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Re: Yet another suspension rebuild
« Reply #9 on: October 05, 2018, 12:16:55 am »
STOP!!
You can not lower the front of an 88 as it has a crossover tube between the forks.
The ends of it set over holes in the tubes that allows oil/pressure to pass between the tubes.

The rear shock is probably ok.
Someone may not have serviced it.
Low or no pressure would also help explain the rough ride.

NOTE: Be careful when you try to put air in the rear.
          If you use a std air compressor that is set to high pressure, It is very EZ to overpressure.
               {as there is little volume in the shock}
          Max pressure is 50 psi.
          Use a regulator to reduce available pressure prior to putting air in the shock.

NOTE II: Because of the low volume, checking the air with a gauge will probably loose 5- 10 psi every time you do it.
                   Makes checking for leaks difficult...

Use a speed handle to install the fork caps.

Ride safe, Ted
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Offline batboy

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Re: Yet another suspension rebuild
« Reply #10 on: October 05, 2018, 02:55:21 am »
Yes, my bike has the crossover tube between the forks. Yes, it can be lowered, I've already done it. I raised both forks together, not a problem.

I haven't done anything to the rear shock yet other than add air with a wimpy wore out 12v compressor you plug into a cigarette lighter. No worries on over-pressurizing, this old pump gives up at about 30 psi. I'm a little confused about what kind of air gauge to use. The manual says don't use a tire gauge, but then doesn't say what kind to use. Thought I'd do the front forks first before messing with the rear shock. Just taking one step at a time.

As for starting the fork caps, I don't have one of those speed handles. Trying to use a deep socket and ratchet, but I  can't seem to press it down far enough to get it started. These new springs are much stiffer than the old ones. I'll give my cordless impact a try tomorrow and hope I don't get it cross threaded.

I only have one tube refilled. I accidentally spilled my expensive fork oil. Hope I have enough for the other fork now.
1988 Kawasaki Concours ZG1000 - Ninja Edition
Bike has the usual accessories and modifications

Offline Bob_C_CT

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Re: Yet another suspension rebuild
« Reply #11 on: October 05, 2018, 09:43:38 am »
You need a no leak tire/air suspension hand pump/pressure gage, Harley sells one. Part Number 54630-03A
You may find a cheaper gage or gage pump look for one no air loss connection. I had a 12v air compressor with gage and I would pump up to 40psi and quickly disconnected.

Don't use impact wrench, take spring out and start cap with no pressure and mark cap and tube when threads disengage. Now replace spring and start cap where both marks align on the cap and on the tube. Maybe use your impact wrench with no power to add some weight behind your push and twist to start the threads. You don't want to cross thread. Impact wrench has many good uses but starting a fine threaded cap is not one of them.
« Last Edit: October 05, 2018, 09:54:33 am by Bob_C_CT »
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Offline batboy

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Re: Yet another suspension rebuild
« Reply #12 on: October 05, 2018, 12:10:25 pm »
Daytona Mike, The progressive 465 series shock is what Murph's sell, right? If this OEM shock won't hold air pressure, I'm definitely getting the 465 shock. Does the replacement 465 shock use air pressure too? The C-14 shock is not an option for me, because I have Soupy's lowering links that will interfere with the spring on the C-14 shock.

Bob, thanks for the air pump info. I hear you loud and clear about not wanting to strip out the fine threads. That's what kept me from using the impact up to this point. I ate a bowl of Wheaties this morning, so I'll try using the manual method one more time before my flabby arm muscles get too tired. By golly, 20 years ago when I was younger and stronger, I could have done this one handed... mumble mumble.


EDIT: Okay, I got the first fork cap back on. I think the Wheaties helped. Now to drain the oil from the other fork and see if I can make an even bigger mess than the first fork. Maybe I'll try the Homer Simpson breakfast to give me strength on the next fork cap (i.e. donuts).
« Last Edit: October 05, 2018, 12:41:09 pm by batboy »
1988 Kawasaki Concours ZG1000 - Ninja Edition
Bike has the usual accessories and modifications

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Re: Yet another suspension rebuild
« Reply #13 on: October 05, 2018, 12:33:52 pm »
My concern is; I think the crossover is positioned over the holes, by resting against the lower triple tree.
I don't recall a clamp?
The way you have it now, it's above the triple tree. Could possibly move?

I was pointing out that if your checking for a leak, the pressure will drop from checking.
ie; Realize it will drop pressure every time you do it.
         Not an ideal way to determine if/how much the shock is leaking air.

Ride safe, Ted
« Last Edit: October 07, 2018, 02:40:31 pm by connie_rider »
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Offline batboy

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Re: Yet another suspension rebuild
« Reply #14 on: October 05, 2018, 12:51:22 pm »
Ted, the crossover consists of two band clamps that fasten to the forks and a tube that goes between them. Stock position is right above the lower triple tree. Now the crossover is higher by a half inch (I can see a space between the triple tree and the crossover). You can't go down (raise the front) more than stock, but you can lower the front (raise the forks). Don't try to move the fork tubes independently or you'll mangle or break the tube. I moved the forks together and carefully measured how much stuck above the top triple tree to make sure both forks were exactly the same.

EDIT: Ted, I looked it over again and checked the manual. I thought the clamps were part of the crossover, but I guess you're right. The clamps are separate parts and are mounted above the crossover to prevent it from moving up. When the crossover is in the stock position, the triple tree prevent it from moving down. Looks like I need to get a couple clamps to attach onto the fork tubes below the crossover now. I don't see why I can't use worm-gear style hose clamps for this situation. Thanks for pointing that out.
« Last Edit: October 05, 2018, 01:08:24 pm by batboy »
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Bike has the usual accessories and modifications

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Re: Yet another suspension rebuild
« Reply #15 on: October 05, 2018, 01:00:44 pm »
Ok, best of luck.

Ride safe, Ted
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Offline batboy

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Re: Yet another suspension rebuild
« Reply #16 on: October 05, 2018, 01:11:45 pm »
Ted, look at my last post, I added a bit to it. You're right about the crossover. In theory the way I have it now, the crossover could technically be able to move down up to a 1/2 inch. Unlikely because it's a tight fit, but possible. Add a couple clamps to the bottom of the crossover and it should be good to go.
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Bike has the usual accessories and modifications

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Re: Yet another suspension rebuild
« Reply #17 on: October 05, 2018, 01:22:01 pm »
I agree. That should "safe" it...

Ride safe, Ted
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Offline batboy

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Re: Yet another suspension rebuild
« Reply #18 on: October 05, 2018, 03:33:06 pm »
Well, I'm no longer a forks virgin. The new Race Tech 1.0 springs are in and the forks are refilled with 15w fork oil. I got lucky and had barely enough fork oil (after knocking the open bottle over yesterday). I just have to put the handlebars/riser back on. Oh, and round up a couple clamps. Thanks to all those people that helped, including past posts that I read during my research on how to do this. Apparently not many folks are doing much suspension work on the early C-10s anymore.
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Offline batboy

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Re: Yet another suspension rebuild
« Reply #19 on: October 06, 2018, 01:47:58 am »
I took a test ride and grinned like an idiot the whole time. The new springs and fork oil refill was much needed. The bike rides much more smoothly. Diving when hitting the brakes hard is vastly improved. I hear people say lowering the front makes the steering quicker. Honestly, I don't know exactly what that means, but the bike seems to be more willing to sweep into the curves just a bit faster. New springs and fork oil only cost $110.

Rear  suspension: I don't know how fast the rear shock loses air psi, but the pressure drops off significantly after a couple days. I don't want to mess with a 30 year old shock that leaks.. Since I stayed under budget on the front suspension, I'm going to bite the bullet and get a new 465 rear shock from Murph's. Hopefully after the shock, that will be about all I need to do for now.

I ran it up to 100 mph to "blow the cobwebs out" as my Dad used to say. Funny thing is before I did that, it idled low and sounded like it was about to die sometimes. Now, after that brief blast to triple digits, it's idling too fast, and seems to be more zippy. I wonder if there was gunk in the carbs that got flushed out when I twisted the throttle?
1988 Kawasaki Concours ZG1000 - Ninja Edition
Bike has the usual accessories and modifications

Offline Daytona_Mike

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Re: Yet another suspension rebuild
« Reply #20 on: October 06, 2018, 10:49:03 pm »
When you took it for a nice run you burned off the carbon on the valve seats and now you have more compression.
 Run the crap out of that engine and keep the revs over 4k.. do not short shift it.. That engine loves to rev and will love you back as long as  long as you dont lug the engine.
Oh your going to love the 465 (no it does not use any air)
Normally aspirated engines have perpetual turbo lag
2000 Red C10 1052 kit 100+HP  + way more torque.
2008  C14 Silver Dammit Full AreaP- Flies are put back in SISF_Flash
2011  KLR650   688 piston ported and polished
2011  KTM 530    This thing is FUN!!

Offline batboy

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Re: Yet another suspension rebuild
« Reply #21 on: October 07, 2018, 11:39:12 pm »
I placed an order for a rear shock. Murph's informed me they've been backordered for 3 months. They will contact their supplier and see what's going on and get back to me.

Well, that don't sound good. Not many options since I have Soupy's lowering links. Guess I'll wait it out and see if they can get restocked.
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Bike has the usual accessories and modifications

Offline Bob_C_CT

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Re: Yet another suspension rebuild
« Reply #22 on: October 08, 2018, 11:43:43 am »
Are you sure that shock will fit with adjustable lowering links.
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Offline batboy

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Re: Yet another suspension rebuild
« Reply #23 on: October 08, 2018, 07:34:21 pm »
Well, considering this is the first time I've worked on a motorcycle rear shock, I must honestly say I personally don't know. But, I stayed up late for a couple of evenings searching through forum discussions. People say the 465 will fit. Others say the C-14 shock and ZZR shock will not. I think there was a mention that Soucy's links works with the C-14 shock, but Soupy's don't. Those names being so similar and both made lowering links, that can't be a coincidence. So, I'm trusting COG members when they said the 465 plays nice with my lowering links. Of course, I can't find that particular post right now. However, I think most of you are very trustworthy from what I've seen, Salute!
1988 Kawasaki Concours ZG1000 - Ninja Edition
Bike has the usual accessories and modifications

Offline MAN OF BLUES

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Re: Yet another suspension rebuild
« Reply #24 on: October 08, 2018, 07:43:12 pm »
Well, considering this is the first time I've worked on a motorcycle rear shock, I must honestly say I personally don't know. But, I stayed up late for a couple of evenings searching through forum discussions. People say the 465 will fit. Others say the C-14 shock and ZZR shock will not. I think there was a mention that Soucy's links works with the C-14 shock, but Soupy's don't. Those names being so similar and both made lowering links, that can't be a coincidence. So, I'm trusting COG members when they said the 465 plays nice with my lowering links. Of course, I can't find that particular post right now. However, I think most of you are very trustworthy from what I've seen, Salute!


name's don't mean a thing...
both products are completely different..
Norm's lowering is not "links", it's the actual rocker the shock and standard links attach to....

http://forum.cog-online.org/c-10-emporium/fs-norm-soucy-link-and-c14-shock/msg650965/#msg650965

Soupy's are the adjustable "dog bones", which by them selves, when using the standard rocker, may not fit correctly with the shock from Murph...

two different methods.

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