DR650 static sag

[ducatijim]

Without a shock out revalve this cant be done on a DR650 which is a real pain as the standard rebound is to low (well I recon it is anyway).

Cheers R

Oops, too far out in left field.

I own one and know well the shortcomings of the Japinc suspension.

My comment was sarcastic. As Bass well knows.

If you increase the preload, the rebound damping will need to be increased to reduce the classic 'DR pogo', encountered with any bump in the surface bigger than a dead midge.

[Bass]

Right, for anyone who is interested, the static sag was 50mm with a spring length of 246 mm.

It's now 35 mm with a spring length of 239mm and will come back to about 50 mm with some baggage aboard.

This actually ties in quite well with the numbers that both Nordie Boy and Crisis Management suggested.

The bike is significantly more stable on the side stand too so, objective achieved. We will see what the ride is like on the weekend, but since all I have done in effect, is change the ride height, I don't expect to feel any difference.

However, ROLL ON MR OHLINS.

Oh and Jamie mate, at the risk of my accomodation for tomorrow night and just to be my usual anal self for a moment, increasing the preload does not of necessity mean an increase in rebound damping because it does not affect the spring stiffness in any way. The main effect is to increase the ride height.
However the 2 adjustments tend to be linked because the most common reason for a preload increase is more weight on the bike and very often, the extra weight requires more rebound damping for optimum control.
In this case, all I wanted was more height.
However, as we both know, the rebound is not adjustable on the DR so it's all bloody semantics anyway.
CU tomorrow

[Ocean1]

Right, for anyone who is interested, the static sag was 50mm with a spring length of 246 mm.

It's now 35 mm with a spring length of 239mm and will come back to about 50 mm with some baggage aboard.

This actually ties in quite well with the numbers that both Nordie Boy and Crisis Management suggested.

The bike is significantly more stable on the side stand too so, objective achieved. We will see what the ride is like on the weekend, but since all I have done in effect, is change the ride height, I don't expect to feel any difference.

Be interested to hear what you think about the change. Cranking the rear up 15mm on the KLX makes a big difference to steering.

[Crisis management]

Be interested to hear what you think about the change. Cranking the rear up 15mm on the KLX makes a big difference to steering.

Yup, it tank slaps at about 120........

I'm fairly light so with just me on it gets a bit vaque over 110 and keeps on getting vaquer (is that a word or should it be vaquerer?) until it wants to go look at bushes and othe interesting things not in the direction I want to go. Bit like a dog really, you know, Ooooh lets have a look at that....

Put 15kgs of gear on the back and it settles down and becomes stable, you'd think with 28 degrees of rake this wouldn't happen but it bloody well does.
The other contributing factor to this is the screen I have fitted. After extensive wind tunnel testing with cardboard & scissors (back & forth over the mangere bridge, handy having a motorway within 1km) I found that a small screen was workable but as soon as it got over 350mm high the front end got steered by the screen.

So, Bass shouldn't have much of a problem as he doesn't run with a screen and is slightly "bigger boned" than me. Be interesting to see tho...

Must hide now.

[Bass]

Be interested to hear what you think about the change. Cranking the rear up 15mm on the KLX makes a big difference to steering.

Any idea why?

It's a tiny change to the steering angle after all.

[Bass]

So, Bass shouldn't have much of a problem as he is slightly "bigger boned" than me.

Must hide now.

Bastard!!
True but Bastard anyway!!

[ducatijim]

The main effect is to increase the ride height.

However the 2 adjustments tend to be linked because the most common reason for a preload increase is more weight on the bike and very often, the extra weight requires more rebound damping for optimum control.

We have been over this crap time and time again. My comment relates to the second quote above, being the most common reason to raise the ride height.

As for the first, well I have never heard of increasing the RIDE height in order to shorten the SIDESTAND!!! Who is the engineer here? Get ur fucken angle grinder out, cut the cunt back then weld a bigger foot at the bottom. Done.

[Ocean1]

Yup, it tank slaps at about 120........

I'm fairly light so with just me on it gets a bit vaque over 110 and keeps on getting vaquer (is that a word or should it be vaquerer?) until it wants to go look at bushes and othe interesting things not in the direction I want to go.

That's one of the negatives at the extreme end of fwd/aft sag adjustments. Sounds like yours is worse than most though. The KLX does get a more vague and willful if it's arse-up or nose-down but not that bad. The badness at the other end is a tendency to wash the front out, and that's more difficult to predict. And just as painful.

How did you come to discover the tankslapperofdoom tendency? were you trying for a lower seat height?

Any idea why?

It's a tiny change to the steering angle after all.

It is, and I agree that it seems an unreasonable effect for such a small variable. I think it's as much to do with the slight reduction in trail as the change in rake. I wouldn't expect a DR650 with 27deg rake to be as sensitive as CM has found, but there you go.

FWIW even smaller adjustments on the Buell produce quite large effects, presumably because of the very short wheelbase and 21 deg rake. 10mm down on the back changes the steering from a seriously sudden and surgically precise, (if a little twitchy) to almost cruiser-like, (slight exageration but you get the idea...)

[Crisis management]

How did you come to discover the tankslapperofdoom tendency? were you trying for a lower seat height?


I wouldn't expect a DR650 with 27deg rake to be as sensitive as CM has found, but there you go.

Tankslapper....a combination of rear ride height / rake and the screen I fitted. DR's are fairly light/vaque in the front IMHO and it obviously doesn't take much to tip the balance. I've not reduced the preload on mine as the springs are marshmellow enough as it is. I'm sure with some set up I could get rid of the tankslapping but it's not much of an issue as most backroads stuff is well below those speeds.

(I grew up on Kawasaki H1's and Suzi T500's so handling has never been something I stress about)

As far as being sensitive....this is Auckland your talking about, we're all new age sensitive types up here!

[Bass]

As for the first, well I have never heard of increasing the RIDE height in order to shorten the SIDESTAND!!! Who is the engineer here? Get ur fucken angle grinder out, cut the cunt back then weld a bigger foot at the bottom. Done.

Well, while I claim to be an engineer, I never claimed to be a good one and I kinda thought that Mr Suzuki was pretty likely to be better than me. So I figured that when he designed the bike, he probably had all this stuff pretty much in balance. Having come to this conclusion, I thought it pretty unlikely that I should have to chop up the machine to get this sorted out.

There are a limited number of adjustments that he left for me to play with (sensible fellow) - suggest to me another adjustment I could use O wise guru.

On top of that, it was pretty much OK when delivered, but started to settle a bit during the last weekend excursion we attended, from which I conclude that the spring and linkages have settled a bit.

Besides, it's only short arse cow cockys whose ring pieces drag on the ground, that have to lower adventure bikes and hack side stands, is it not? (or women, but we won't go there)


P.S. It's also why Mr Suzuki makes quads for cow cockys isn't it?

[Bass]

We have been over this crap time and time again. My comment relates to the second quote above, being the most common reason to raise the ride height.

Excellent!
I see that you retain some of the stuff I taught you!
I just thought that some stroppy heifer might have kicked you in the nuts again and caused you to forget it all.
I see I was wrong though and I humbly apologise.

[Ocean1]

I grew up on Kawasaki H1's and Suzi T500's so handling has never been something I stress about

Ah, quite.

Ain't modern bikes great, one doesn't actually need to stop for corners, get off, push it around and take off agin'.

[Bass]

The badness at the other end is a tendency to wash the front out, and that's more difficult to predict. And just as painful.

Again I fail to comprehend, which is not all surprising and almost commonplace.
Why would this adjustment influence front end grip?

I can see that changing the rake influences the lean angle that the wheel adopts as it turns, but we are still talking miniscule changes.

[Bass]

Tankslapper....a combination of rear ride height / rake and the screen I fitted. DR's are fairly light/vaque in the front IMHO and it obviously doesn't take much to tip the balance.

I fiddled around with model aircraft for years - in particular the racing kind. Along the way, I learned a little about aerodynamics and stability. I strongly suspect that the screen is responsible for the much greater proportion of the problem, particularly since as you point out, the steering is pretty light anyway.

While on this topic, what symptoms was it that pushed you out on to the Mangere bridge with cardboard and scissors?

[tri boy]

[QUOTE=Bass;1373318]I fiddled around with model aircraft for years - in particular the racing kind. Along the way, I learned a little about aerodynamics and stability. I strongly suspect that the screen is responsible for the much greater proportion of the problem, particularly since as you point out, the steering is pretty light anyway.

...or that Ian's piddly little biceps couldn't hold a teaspoon of sugar in a stable manner, let alone a motorcycle handlebar