Suspension heating up?

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KarlP
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Suspension heating up?

Post by KarlP »

I have a situation that is puzzling, but may be normal.

This is on the '99CR250 but it does have a KDX motor so I feel I can ask here. Anyway, you guys are smart.

When I am about 45 minutes into a ride, I feel like my suspension is getting harsh.
I've spent a lot of time tuning and am generally really happy with the bike. for the first 10 minutes or so, it is also kind of harsh/stiff, then it is great, then from about 45 minutes on it gets kind of harsh. It may be that I'm getting tired and can't keep my butt off the seat anymore......but something seems to be happening.

If the suspension is heating up and the fluid viscosity is changing, which way do you suppose I might go with the clickers to compensate? It seems to be shock only, but you never know.

I'd be O.K. with an even worser ride the first ten minutes if it meant an even betterer ride from 45 on.

The shock does get pretty hot, too hot to touch but not hot enough to sizzle water. About 130 F I'd guess.


Suspension was revalved and resprung by a local guy early this year. Last month I inspected and regreased the rear linkage.

Thanks for any help!
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Post by Colorado Mike »

I never felt my shock to see how hot it gets. I'm wondering since you had it revalved last year if the dude didn't bleed the shock properly. Air in the oil will cause it to foam and act wonky. Also, make sure it's not leaking oil, and that your nitrogen bladder and pressure is good. Testing this wih a tire gauge is bound to screw it up though. One pfft can be a loss of 20 lbs of pressure. better to just take it to a shop and have them vent and re-pressurize, that way you should be getting real nitrogen too.
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Post by scheckaet »

fork bleeder for the front end, degas when you feel them getting harsh.
shock beeing hot to the touch seems a bit odd. Never noticed anything like that (but I never tried to stick my hand on it either) Does the local shop know what they're doing? Good reputation? Type of oil used?
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Post by KarlP »

Yeah, I'm going to get some fork bleeders. I can't say the forks are getting harsh, it feels more like the rear. I stopped yesterday evening at 1/2 hour and opened the fork bleed screws. Pfffftt from each. When I continued the ride everything felt the same (still harsh) but it is hard to tell after taking a break like that
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Post by kawagumby »

+ 1 for having the shock bled and recharged.
Shocks do get very hot under riding stress, that part is normal.
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Post by canyncarvr »

Shocks get hot?

Oh yeah!!

A fluid that is worth anything is going to be able to handle it. I'm saying I would not expect a viscosity change that you would feel given the temp ranges a (good) shock oil works in.

Re: '..bled and recharged'

To be clear (I make things difficult on purpose)..that is NOT a reference to the bladder only...right? You mean a fluid change and bladder recharge?

Take your shock off, remove the spring. Manually compress the shock and let it rebound. You should hear nothing in the way of squirts, spurts, or champagne bubble pops. If you do, then..

+ 2 for having the shock bled and recharged.

If you don't hear any of that? Then....

+ 2 for having the shock bled and recharged.

:wink:

..and use some 'real' fluid.

What is the bladder pressure? Shock pumps have a no-loss valve. You should be able to thread a shock pump onto the cannister valve to check the pressure and not lose any of it. (Mine does..as far as I've been able to tell, anyway. I got it for my KDX shock, didn't use it, but do use it on my Honda forks.)

Maybe it's low. Maybe something leaked.

Maybe you don't HAVE any bladder pressure (leaks/loss already noted).

If your local guy is easy-local..I'm sure he'd be glad to check it for you and it wouldn't be a hassle for you.

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Post by KarlP »

Thanks for the help and input. I'm not going to heed it, of course (just yet. I know Stubborn)

"{{If the suspension is heating up and the fluid viscosity is changing, which way do you suppose I might go with the clickers to compensate? It seems to be shock only, but you never know.

I'd be O.K. with an even worser ride the first ten minutes if it meant an even betterer ride from 45 on.}}

I think I'm gonna try a couple clicks stiffer for both rebound and compression on the shock next time out. Or maybe up a bit on the HSC. Hopefully I won't break my neck in those first 10 minutes and all will be well.

If that doesn't work after a couple of tries I will pull the shock and check for squirts, spurts, or champagne bubble pops. My shock guy is local and will change the oil if I ask him to.

I have found that this chassis ('99 CR250) is very sensitive to suspension settings and sag/fork height change. It took a long time to get it this close. I think woods riding takes very carefully tuned suspension and it doesn't take much to get it out of whack. I know sometimes we'll come off the trail and take jeep roads home and I can detect no problem at all on the jeep roads.

So anyway, here's my plan-
Up two clicks on comp. Go for a ride, 45 minutes minimum non stop.
Up two clicks on rebound (having put the comp back). Go for a ride, 45 minutes minimum non stop.
Up a 1/4 turn on HSC (having put the rebound back). Go for a ride, 45 minutes minimum non stop.

((Big sigh...)
Maybe I won't do anything. The above sounds like 2.25 hours of riding around wondering about oil and shims and viscosity and oil and settings and spring preload and .......

Hmmmmm
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Post by canyncarvr »

Re: '..which way do you suppose I might go with the clickers to compensate?'

Oh. You wanted an answer to your question??

picky picky picky...

If it's an issue of the viscosity changing due emulsification brought on by improper/wrong/failed pressurization or an improperly filled/bled shock body, the direction you would want to go is 'stiffer' on stuff.

But..you know that already.

Turns on HSC? :hmm:

I missed something. Where'd you get that?

A BTW...but what does 'harsh' mean in this case? Is it a matter of the suspension moving too far too fast? So, if you run over the proverbial 2x4 nailed flat on the road, your suspension is going to move 5"?

That you have the perception to notice a difference at the XX-minute mark says you likely have the ability to fix it.

Unfortunately, there is likely still something that needs to be repaired even if you DO get it 'fixed'.


('repair' being something done, a course of action taken to resolve a problem or issue, 'fix' being a work-around, band-aided, make-do, bootstrap event)

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Post by KarlP »

Yeah, it needs to be REPAIRED.

A few of us went out to a motorcycle trail in the DeSoto National Forest. Faster single track than I normally ride. There is a 17 mile loop, at 5 miles you can cut back to the parking area if you want.

While the other guys were getting ready I ran the 5 mile option. As usual shock action started getting harsh. I increased comp and HSC a bit and we all took off. The shock felt great again until about mile 10.

We took a little break and then started on another loop. Within a 3-4 miles the shock started harshing up again. I bailed out at 5 miles.


What "harsh" means to me is that the shock can become a bump amplifier. A 3" root hit at speed ought to be sucked up, not feel like a 6" root and a kick in the a$$. I also end up with crappy steering and it can become a scary ride.

I mention HSC because this is on the '99 CR250 hybrid.

Off with the shock!
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Post by canyncarvr »

Re: 'What "harsh" means to me is that the shock can become a bump amplifier.'

I'm not a shock doktor, and I don't play one on TV neither..but that sounds to me like an emulsification problem.

OK...so CRs have HSC shock adjustment. Neat!!

I tried to turn the nut on my KYB shock to adjust the HSC once. It appeared to be stuck. :hmm:



..just kidding.


Good luck getting it fixed. It might be time to try a different shock-guy..or just do it yourself.

I used RaceTech's oil when I serviced my shock awhile back. I'm not an oil doktor either, but I was happy to find that the shock worked as well when I was done as it has in the past when I sent it off to a REAL Shock Dr. I'll take that as at least some indication that the oil isn't complete crap.

How's THAT for an endorsement?
One user wrote:This product is NOT complete crap!!!

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Post by KarlP »

Yeah, I may well send it off elsewhere, or learn to do it myself. The guy I've used in the past has a very messy bench and a large assortment of hammers. :blink: The problem with doing it myself is that it WILL be more expensive and take longer. Experience has shown that I will have to do it twice (at least) to get it right.

I just got done reading a series of posts on the merits of nitrogen and proper gas pressures and the effects of heat on that pressure. Got me thinking, which is bad.

:lol:
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Post by canyncarvr »

I got a shock pump because I am not convinced that nitrogen is that big a deal. I have thought of putting the shock in a plastic bag..filling the bag with either compressed air (it will have less moisture in it than ambient air) or some dust-off stuff, THEN pump it up. A shock pump is quite small, the body would easily fit in the bag with your choice of 'gas'.

Otherwise, some shops will pressurize a shock they didn't put together...some won't. Check BEFORE you need it to keep the surprise level down. I did get my shock pressurized by the local Yamaha outfit. $15.

Just do it. There are a number of advantages. When you get it done the first time, you will think, 'Why haven't I done this myself ALL the time?' You will do it more often..and almost always, more often is better when it comes to suspension maintenance. How many riders actually change their suspension fluids even at a minimum level (annually)?

I KNOW my shock works MUCH better with new oil. I've proven that to myself over and over. ..and I STILL haven't gotten it done but around an 18 month timeframe. After finally getting around to doing it myself and being happy with the result...I don't suppose it will be 18 months any more.

Let us know how much fun you had doing it yourself!!!

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Post by Colorado Mike »

changing the shock oil reall isn't that big of a deal, I can't remember needing any special tools either. If you decide to do it yourself change the seal and bushing. When I do it again I'm going to just buy a complete seal head assy. from Race Tech or similar. un-crimping the seal head is kind of time consuming I thought, and the assy, wasn't much more than the parts. Like CC said, Use good oil, it's expensive but you're saving a ton by doing it yourself, and there is a difference.

When I was done, I charged it with air to about 20 lbs. just to see if it would hold together, and hold pressure. it did, so I charged it to about 120 psi and left it like that so the bike shop couldn't whine that they can't take the risk of it blowing apart after a know-nothing dweeb like me rebuilt it instead of paying their know-nothing retards. They charged me about $15 to recharge with Nitrogen.
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Post by muddertrucker »

RE:Yeah, I may well send it off elsewhere, or learn to do it myself. The guy I've used in the past has a very messy bench and a large assortment of hammers.

But he probably calls them calibrated taping devices...right :lol:
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Post by canyncarvr »

Your shock's a Showa?

RaceTech seal heads for Showas run $50-65.

The KDX KYB comes apart simply enough. Don't know about a Showa. I know a shock off a ('a' meaning one..not ANY one...so don't pick about it) Yamaha requires some metal removal in the cap area to get the outer clip out/off 'cuz there is an INNER clip that won't let you push the cap in.

If you compress the cap enough to see a clip with 'ends' on it you can get to with a snap ring plier, you're safe.

IF the cap doesn't want to push...there may be a clip on the INSIDE. Put too much pressure on the cap and you WILL damage the shock....it's not going to squeeze past the inside clip (assuming in this made-up example that there is such a thing).

Ask bradf. He's got a Showa on his bike.

Good luck with it!!!

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Post by grump99 »

>|<>QBB<
canyncarvr wrote:I got a shock pump because I am not convinced that nitrogen is that big a deal.
Out of curiosity, have you tried this setup yet? Have you noticed any difference in performance compared to nitrogen?

I'm due for an oil change and the closest place that does the service is about an hour away. I'd rather just pump it up myself if it works just as well.



:mrgreen:
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Post by canyncarvr »

No. I have not.

I'm waiting for YOU to tell me how well it works!!


A shock pump runs around $50. Make sure you get one that has the correct scale on it. A pump guage that shows a max of 120psi isn't going to work. When I got mine (a Progressive pump) I could specify which guage I wanted.


There are lots of opinions from lots of people that say using anything BUT nitrogen is just plain stoopid. I think they've all talked to each other and agree to say the same thing. AIR is 80% nitrogen..so, using a baseball analogy, batting .800 is a winner, ain't it?

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Post by scheckaet »

It is my understanding that one of the reason to use nitrogen is because it's an inhert gas and it won't eat the rubber part of the bladder like air would (air = 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide)
Some other said the N2 will not heat up as fast as air (i.e expand and increase pressure = messing up your VERY WELL TUNED suspension :mrgreen: ) but I'm no good in thermodynamics so can't really comment on that, make sense.
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Post by canyncarvr »

I'm familiar with all the arguments.

If 'air' put into a bladder is going to 'eat it'...then breathing all of a sudden becomes a very dangerous event, donut?

And how about moving your family at 70mph down the freeway on rubber things filled with air? Better drive faster!!!...'cuz the tires are getting EATEN as we speak!!

:wink:

Not to mention that the same air is on the OUTside of the tires..doing MORE eating!!

I haven't used air..I can't comment on its use one way or the other. I do think the N2 only crowd makes a bit a big to-do over not much.

If I as a world-class super-crosser, maybe it would matter.

BTW...I happen to know that 'air' is made up of considerably more things than the list above. Here's the facts of the matter:

The rest (other than nitrogen) is made up of oxygen, argon, water vapor, cat dander, bad breath and coal-plant particulates.

I know that's true 'cuz I read it on the innernet.
.
.
.
.
an everyone knows THAT'S mostly nothing but hot air.

:wink:

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Post by scheckaet »

Yes indeed breathing air is dangerous it causes free radical in your body and gives you cancer and such :mrgreen:
More seriously, I would think it makes the rubber more porous and turns into a slow leak, not as bad in a tire as it would on a shock.

Note: I did try air in my shock a few time (used a very "accurate bicycle pump") and couldn't tell any difference. Could be:
a, cuz I'm not a world class rider
b, my shock was already shot and needed a real rebuild
c, all of the above

Yeah you guessed it c is right. I sent the shock to fredette (did a revalve at the same time) and wow made a world of a difference.
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