My CB900 seems to have developed a new, mild-but-detectable weave/wobble
going through medium- to high-speed turns. It feels like the front end is
seeking a line, but just wanders back and forth without settling down. It's
only there in a turn, no sign of wobble or headshake going straight. What
are the most likely causes of this behavior?

The tires are properly aired, the front is about 50% done with no obvious
cupping or unevenness. The rear is closer to done, starting to square off
some. I've had rear tires that were flatter than this without causing a
wobble, just that funny "step up/step down" feel to entering and leaving
turns.

My list of suspects, in order:

Rear shocks. I probably should have changed these long ago. Now they're
both covered in oil and road dirt, and might not be providing any real
damping anymore. They're the stock adjustable shocks. Last time I checked
they were still available from Honda, but for a pretty penny indeed. I know
that DK sells affordable aftermarket shocks that'll fit. They're
non-adjustable, but since I never carry a passenger I see no problem there.

Swingarm bushings. Anytime I've got the bike on the center stand I give it
a shake to see if they're loose (they aren't), and a frozen swingarm would
be too obvious to miss. I doubt anyone's actually serviced the swingarm
since the bike was built. It's about time for a new chain anyway, and if
I've already got the shocks off, why not do the swingarm too?

Head bearings. Also unserviced since the beginning of time. But I do check
them for play every now and then. I don't wheelie or run over curbs, so
they shouldn't have any notching. Doing an actual service on these is
something I very much do not look forward to.

Wheel bearings. They're the sealed type, and were in good shape when I last
had the wheels off two years (~5,000 mi) ago.

The tires themselves are five years old. Could the rubber age and change in
ways that affect handling like this? It's garaged full time, and I don't
see any cracks or other signs of weathering.

Forks. Unlikely, since I overhauled them two years ago (seals, bushings,
oil). No leaks, air pressure is OK. As air forks they're a little
"sticky", but they've always been. I'll go over the triple tree and
retorque all of the clamp bolts.

Brakes dragging. Shouldn't be, since I put anti-seize on the slide pins,
but I guess they might anyway. That one's easy enough to check.

The last, least likely possibility is that every single sweeper I've ridden
in the past 300 miles is all lumpy and frost-heaved. Not impossible,
considering the DOT in question, but still....

Looks like I've got a few shop days in my future. Anything else I should
look for?

--
'73 CB450K
'82 CB900F (x2)
'04 FSC600 (SWMBO)

On May 28, 8:15*am, nob...@xmission.com (Scott) wrote:
> My CB900 seems to have developed a new, mild-but-detectable weave/wobble
> going through medium- to high-speed turns. *It feels like the front endis
> seeking a line, but just wanders back and forth without settling down. *It's
> only there in a turn, no sign of wobble or headshake going straight. *What
> are the most likely causes of this behavior?

Your front tire's rubber is probably "dead", and it cannot absorb and
damp out small imperfections in the pavement. A matched set of new
tires will be "cushy" and the extra grip will damp out wobbles and
weaves.

If your rear shocks are worn out and don't damp the up and down action
of the
rear wheel very well, you'll notice a slow speed *wallowing* and the
handlebars will waggle back forth very slowly.

¿ <(E-Mail Removed)> wrote:

>
> Your front tire's rubber is probably "dead",

After five years? No.

> and it cannot absorb and
> damp out small imperfections in the pavement. A matched set of new
> tires will be "cushy" and the extra grip will damp out wobbles and
> weaves.

>
> If your rear shocks are worn out and don't damp the up and down action
> of the
> rear wheel very well, you'll notice a slow speed *wallowing* and the
> handlebars will waggle back forth very slowly.

No, you won't. You'll notice a bouncing of the back end, all spring and
no damping.

Wrong again.

--
BMW K1100LT Ducati 750SS Honda CB400F SH50 Triumph Street Triple
Honda XBR500 MZ TS250/1.
If you don't know what you're doing, don't do it.
chateau dot murray at idnet dot com

Scott <(E-Mail Removed)> wrote:

> My CB900 seems to have developed a new, mild-but-detectable weave/wobble
> going through medium- to high-speed turns. It feels like the front end is
> seeking a line, but just wanders back and forth without settling down. It's
> only there in a turn, no sign of wobble or headshake going straight. What
> are the most likely causes of this behavior?
>
> The tires are properly aired, the front is about 50% done with no obvious
> cupping or unevenness. The rear is closer to done, starting to square off
> some. I've had rear tires that were flatter than this without causing a
> wobble, just that funny "step up/step down" feel to entering and leaving
> turns.

It's not so much the rear tyre wear (though this is shot) but the
combination oif one worn and one relatively unworn tyre. I'd replace
both.

>
> My list of suspects, in order:
>
> Rear shocks. I probably should have changed these long ago. Now they're
> both covered in oil and road dirt, and might not be providing any real
> damping anymore. They're the stock adjustable shocks. Last time I checked
> they were still available from Honda, but for a pretty penny indeed. I know
> that DK sells affordable aftermarket shocks that'll fit. They're
> non-adjustable, but since I never carry a passenger I see no problem there.

The shocks are shot, yes. Replace ''em.
>
> Swingarm bushings. Anytime I've got the bike on the center stand I give it
> a shake to see if they're loose (they aren't), and a frozen swingarm would
> be too obvious to miss. I doubt anyone's actually serviced the swingarm
> since the bike was built. It's about time for a new chain anyway, and if
> I've already got the shocks off, why not do the swingarm too?

Good plan.

>
> Head bearings. Also unserviced since the beginning of time. But I do check
> them for play every now and then. I don't wheelie or run over curbs, so
> they shouldn't have any notching. Doing an actual service on these is
> something I very much do not look forward to.

Have you checked for nothes? I bet they have 'em.

>
> Wheel bearings. They're the sealed type, and were in good shape when I last
> had the wheels off two years (~5,000 mi) ago.

OK
>
> The tires themselves are five years old. Could the rubber age and change in
> ways that affect handling like this?

Yes, but not in a mere five years, whatever Krsuty thinks.

> It's garaged full time, and I don't
> see any cracks or other signs of weathering.

Good.
>
> Forks. Unlikely, since I overhauled them two years ago (seals, bushings,
> oil). No leaks, air pressure is OK. As air forks they're a little
> "sticky", but they've always been. I'll go over the triple tree and
> retorque all of the clamp bolts.
>
Fine.

To be honest, it's most likely to be an evil combination of dodgy tyres,
worn head races, knackered shocks and a 30 year-old bike that wasn't a
great handler to begin with.


--
BMW K1100LT Ducati 750SS Honda CB400F SH50 Triumph Street Triple
Honda XBR500 MZ TS250/1.
If you don't know what you're doing, don't do it.
chateau dot murray at idnet dot com

On May 28, 12:03*pm, totallydeadmail...@yahoo.co.uk (Limey Wanna
Cracker?) wrote:
> ¿ <macmi...@gmail.com> wrote:
> > Your front tire's rubber is probably "dead",
>
> After five years? No.

Some rubber compounds can be "dead" in a matter of *hours*, asshole.

>
> > If your rear shocks are worn out and don't damp the up and down action
> > of the
> > rear wheel very well, you'll notice a slow speed *wallowing* and the
> > handlebars will waggle back forth very slowly.
>
> No, you won't. You'll notice a bouncing of the back end, all spring and
> no damping.

Don't understand much about hydraulic shock technology, asshole?

Always remember, I'm a cracker. You can eat me.

On May 28, 8:15*am, nob...@xmission.com (Scott) wrote:

> Forks. *Unlikely, since I overhauled them two years ago (seals, bushings,
> oil). *No leaks, air pressure is OK. *As air forks they're a little
> "sticky", but they've always been. *I'll go over the triple tree and
> retorque all of the clamp bolts.

Stop putting *air* in the forks. That could be a reason for why your
front tire doesn't stick well enough to go straight without weaving.

Google for "CB900 +fork springs -progressive" to find out what kind of
springs are available for the CB900, other than Progressive Suspension
springs.

The problem with PS springs is they have more coils so they take up
more space in the fork leg. That upsets the fork oil level, you cannot
use the recommended amount of fork oil called for in the owners manual
and PS cannot tell you the correct amount of oil to use because they
make the same spring for multiple motorcycles.

Oh, and don't pay much attention to "The Older Gentleman". He just
hangs around the motorcycle newsgroups looking for arguments.

Before you know it, he'll have you kissing his ass and apologizing for
somehow insulting his expertise...

On Thu, 28 May 2009 20:03:15 +0100, in rec.motorcycles.tech,
(E-Mail Removed) (The Older Gentleman) wrote:

>> Head bearings. Also unserviced since the beginning of time. But I do check
>> them for play every now and then. I don't wheelie or run over curbs, so
>> they shouldn't have any notching. Doing an actual service on these is
>> something I very much do not look forward to.
>
>Have you checked for nothes? I bet they have 'em.

After 67,000 miles? I'd hope for more life out of them. And I'm intimiated
by the job. I'll have to talk myself into it.

>To be honest, it's most likely to be an evil combination of dodgy tyres,
>worn head races, knackered shocks and a 30 year-old bike that wasn't a
>great handler to begin with.

I wouldn't know, I've got very little experience on other bikes. But it
handled a lot better this time last year, so something's wrong.

--
'73 CB450K
'82 CB900F (x2)
'04 FSC600 (SWMBO)

On Thu, 28 May 2009 17:24:37 -0500, in rec.motorcycles.tech, "Who Me?"
<(E-Mail Removed)> wrote:

>Do you date fat chicks too ?? ;-)

Only the ones my wife tells me to.

>Do the tires.....one at a time if you insist; back first.......before you
>start "fixing" things that aren't broken.

That's fair. Also easier. But it's called "preventive maintenance" for a
reason. Personally I don't wait for my camshafts to spall before I add more
oil.

--
'73 CB450K
'82 CB900F (x2)
'04 FSC600 (SWMBO)

On Thu, 28 May 2009 14:25:50 -0700 (PDT), in rec.motorcycles.tech,
=?ISO-8859-1?Q?=BF?= <(E-Mail Removed)> wrote:

>Stop putting *air* in the forks. That could be a reason for why your
>front tire doesn't stick well enough to go straight without weaving.

As long as they're stock forks, I'll follow the manufacturer's directions.
I already tried running them with no air. It was NOT an improvement.

>Google for "CB900 +fork springs -progressive" to find out what kind of
>springs are available for the CB900, other than Progressive Suspension
>springs.

Yeah, I've tried to find progressive springs that aren't Progressive
springs. Clever bastards, aren't they?

>The problem with PS springs is they have more coils so they take up
>more space in the fork leg. That upsets the fork oil level, you cannot
>use the recommended amount of fork oil called for in the owners manual
>and PS cannot tell you the correct amount of oil to use because they
>make the same spring for multiple motorcycles.

The same oil level (distance from the top of the tube) should be pretty
close to right, or a good place to start. Some manuals give that figure.
Mine only gives the volume of oil, so I'll have to measure the level myself.

>Oh, and don't pay much attention to "The Older Gentleman". He just
>hangs around the motorcycle newsgroups looking for arguments.

And you're dumb enough to oblige him! Both of you are smart and have
offered many pieces of good advice (and some bad), but both of you are
attention whores. If you didn't enjoy arguing in public so much, you'd KF
or ignore each other.

--
'73 CB450K
'82 CB900F (x2)
'04 FSC600 (SWMBO)

On May 28, 6:34*pm, nob...@xmission.com (Scott) wrote:

> As long as they're stock forks, I'll follow the manufacturer's directions..
> I already tried running them with no air. *It was NOT an improvement.

Air-assisted forks use a weaker spring than non-assisted forked would
use and
no air at all would probably tend to make the handling squirrely on
corner entry when riding vigorously.

> Yeah, I've tried to find progressive springs that aren't Progressive
> springs. *Clever bastards, aren't they?

I installed PS springs in two motorcycles before I realized what was
going on.

I tried to road race the first bike and the handling was terrible. I
had no idea what was going on to make the bike wobble so badly.

Race Tech makes all straight wound springs, but I doubt they have any
for your machine. If you're going to try running with no air, use a
pair of short compression springs to replace any spacers on top of the
stock springs.

I'm amazed at what Lowes has in all those boxes in their hardware
department..

> The same oil level (distance from the top of the tube) should be pretty
> close to right, or a good place to start. *Some manuals give that figure.
> Mine only gives the volume of oil, so I'll have to measure the level myself.

Progressive recommended 150 mm or less of oil from the top of the
inner tube with the fork tube compressed all the way.
>
> >Oh, and don't pay much attention to "The Older Gentleman". He just
> >hangs around the motorcycle newsgroups looking for arguments.
>
> And you're dumb enough to oblige him! *Both of you are smart and have
> offered many pieces of good advice (and some bad), but both of you are
> attention whores. *If you didn't enjoy arguing in public so much, you'dKF
> or ignore each other.

I tried to ignore the asshole for the first eight years he followed me
around from group to group.

He's like a fag, he can't be insulted into shutting up.