?Fork oil

The manual for my 1979 Honda CB 650 simply calls for using ATF in the front
forks, no specs given. Can someone translate 1979-speak "ATF" to the kinds
of ATF available nowadays to choose from? Thanks,

frog

 

The reason for using ATF in those days was two-fold.

The first reason was that it didn't entrain air (foam up) during rapid
stroking, which caused inconsistent damping over rough surfaces.

The other reason was that ATF used to contain whale oil as a friction
modifier.

Importation of whale oil was banned later.

ATF might be about 2.5 weight or 5 weight and you'd probably be better
off using
a light weight fork oil intended for motorcycles.

 

That is because nobody was making fork specific oils at the time. I'd
suggest start with something in the 10wt range and working from there.
Most likely you'll end up with a heavier oil as the only way to adjust
your front suspension is with the oil weight and the springs.

http://www.google.com/search?source...lz=1T4GGLL_enUS374US374&q=motorcycle+fork+oil

is good start. I also suggest you look up some type specific web pages
for your CB650.

I've GL1000 of similar vintage and am running 10wt, may bump up to
12wt or even 15wt but that is becasue I don't piddle along...I push
that old frame and suspension technology to it's limits.

 

Not true, not true at all...

Maybe in the 50's you stupid git.

iirc that was in the 50's.

There is little consistance in weights of atf. That's a fact that you
obviously aren't aware of.

Then again considering that YOU Krusty Kritter don't know much about
anything you can't wiki it's not surprising.

 

Thanks for the info, but that brings it back around to my question about
what did Honda mean when they used the term "ATF" in 1979. You can read
hundreds of well-versed opinions from here and from Googling, many by oil
experts (as in "Amsoil 5wt. is less viscous than other 5wts". HUH?). If
going from 5wt. to 15wt. makes that much difference (or not) it's all
guessing unless you know how your bike handles with one or the other.

I would like to change my fork oil to the factory recommendation to start
with. Then if it needs a little heavier or lighter I can have an optimum
baseline to judge from.

Does anyone know what Honda meant by "use ATF" back in '79? You know, like
was it a Dexron thing, or some other standard?

Thanks, frog

That is because nobody was making fork specific oils at the time. I'd
suggest start with something in the 10wt range and working from there.
Most likely you'll end up with a heavier oil as the only way to adjust
your front suspension is with the oil weight and the springs.

http://www.google.com/search?source...lz=1T4GGLL_enUS374US374&q=motorcycle+fork+oil

is good start. I also suggest you look up some type specific web pages
for your CB650.

I've GL1000 of similar vintage and am running 10wt, may bump up to
12wt or even 15wt but that is becasue I don't piddle along...I push
that old frame and suspension technology to it's limits.

 

Automotive transmission engineers formulated different ATF's because
of problems inherent to automtive transmissions.

A motorcycle fork doesn't *have* those problems.

Most riders don't know that a fork seal works like a one-way air valve
when the forks are stroking rapidly over rough pavement.

This traps air, which effectively increases the spring rate by adding
an unwanted air spring.

My 1968 Yamaha 250 Single Enduro had special air valves in the fork
caps that could be used to "burp" excess air trapped pressure.

Air also gets entrained in the fork oil as the fork strokes up and
down.

Also, remember that a damper rod fork is velocity sensitive because of
the rebound orifice holes limiting flow exponentially at higher
stroking speeds.

The Japanese motorcycle industry used the thinnest oil they could use
and still get rebound damping.

Maybe it was 5 weight, 10 weight at the maximum.

The motorcycle magazines accused Japanese motorcycle manufacturers of
using "fish oil" in their forks, and the motomavens would recommend
switching to an American brand of fork oil, which helped out the
aftermarket lubricant industry.

Unaware of the orifice flow limitations, American riders would install
15, 20, or even 30 weight oil in their forks and they got a very harsh
ride over sudden sharp-edged bumps.

Some American suspension "experts" started talking about air getting
trapped in the forks and entraining in the fork oil because they
didn't know that fixed orifices were so velocity sensitive,

An article in one of the magazines (Cycle?) during the late 1960's/
early 1970's involved filling up forks with various fork oils and
stroking them on a machine while measuring the damping curves.

Spikes in the damping curves were noted, and oil consistency was
questioned.

The series of tests was performed with a certain laboratory oil and
interested riders demanded to know where they could get that oil,
which was unavailable at a price that riders would be willing to pay.

The motomavens suggested using ATF as a consistently formulated
suspension oil, even though there were definitely differences in the
consistency from one manufacturer to another.

The ATF recommendation got back to Japanese engineers, so they adopted
the
suggestion, just as they adopted many other ideas which came from the
Southern California hot rodding community, where the enthusiast was
often working in the *movie industry* and, if they had a degree, it
was in *cinematography*!

The California hot rodders simply had more practical experience than
the Japanese engineers!

As S'mee said, 10 weight fork oil will probably give you a baseline
feel and what you want to do is go out and ride your typical road and
see if you feel like the motorcycle controllable over undulating bumps
and that the fork doesn't feel harsh over sudden, smaller, sharp-edged
bumps.

If your wrists are getting tired and it feels like you're riding a
jackhammer, the oil weight is too heavy to flow consistently through
the orifices in the damper roads.

Race Tech (www.racetech.com) has developed the adjustable Gold Valve
Emulator which makes a damper rod fork behave like a more modern
cartridge fork by blowing off excessive oil pressure on rapid
compression.

Maybe there's an emulator kit for your machine. Also, look up the
recommended fork oil weight on that website.

 

exactly that. They were giving the best answer they had to the issue
"what do we use for oil in the forks Akama?"

Why go with the OLD ineffective fork oil? It doesn't work as well as
newer better oils do. Also there is absolutly no way to tune your
front end with ATF it's shit, period.

Answered already.

 

SNIP

What utter shite. YOu know **** all about motorcycles and have rip off
web sites to get your info. You do not ride and you've NEVER riden a
motorcyclye in your pathetic life.

LOL see you prove me right.

Maybe? MAYBE? they don't and guess what they haven't suggestion for
his bike. I know I've been through their excellent page looking up
stuff for my self. I suggest you stick to what you know...being a
racist pedarast and shetland molester.

 

No, they don't

No, it doesn't.

So why don't all motorcycles have them now, genius?

So this is where you got 'whale oil' from? And whales aren't even
fish[1].

[1] They're insects.

 

exactly that. They were giving the best answer they had to the issue
"what do we use for oil in the forks Akama?"

Why go with the OLD ineffective fork oil? It doesn't work as well as
newer better oils do. Also there is absolutly no way to tune your
front end with ATF it's shit, period.

**************

In my CB200 I used a 50/50 mix of teflon grease and Slick50, firstly I don't
like wallowy bikes that dive to the stops on heavy braking, secondly it
doesn't dribble out the bottom of the fork gaiters when the knackered seals
leak.

The ride was just how I like it and it would have passed the MOT if the
swingarm hadn't rusted through.

 

On Jun 13, 2:17 pm, "ian field" <>
wrote:
SNIP

<rolls eyes> fat lot of help that was...

 

On Jun 13, 2:17 pm, "ian field" <>
wrote:
SNIP

<rolls eyes> fat lot of help that was...

I was slightly puzzled that the MOT test guy didn't seem to have noticed
that the speedo was stuck at just over 30mph. He didn't write it on the fail
report.

 

In those days, ATF could mean several things. Usually, it
meant a Dezron spec which was formulated to the specs of
several automakers. Dexron was the successor to the old
Type A designation . General Motors was the primary but,
Chrysler had used Type A from the early sixties and went
along with GM adding their own spec reference as do Ford
starting with the 1976 model year. Somewhere in the early
seventies, the Dexron designation replaced the Type A
designation. If you test samples from various makers of
Dexron or any of the others, you will find rather large
variations in the viscosity which is a primary consideration
in motorcycle fork oils. In 1979, a reference to "ATF"
would usually have meant Dexron or Dexron II since it was by
far the most common. Type F spec'd for older Ford products
would not have been used since it has a friction modifier to
help the trans clutches get a bite at lower pressures.

I have had several seventies machines on which I replaced
the fork oil during maintenance. By far, the best thing to
do and save yourself much consternation, swearing and time
is start with a name brand fork oil since the viscosity is
well controlled within brand lines. The same viscosity in a
different brand may perform differently. My personal
favorite is Bel-Ray - there are several other excellent
brands. They are all available in various weights as well
as multi-grades.

My own preference for fork oil in all street/highway riding
is determined by ride quality and handling. An oil too
light allows the fork to compress or rebound too quickly and
possibly bottom out on sudden hard braking and allows too
much nose dive for me. Too viscous and you will find your
teeth rattling on rumble bars. You can tune the fork to
your preferences. At 240 lb, I am sure the forks require a
different oil for me than a lighter rider for similar
results.

Bottom line, pick your brand and weight of fork oil as a
starting point. Measure the oil level and quantity very
carefully. On my bike, the manual gives an oil level as
measured from the top of the fork tube with the spring
installed. To get this, I use either a piece of wooden
dowel stock readily available at places like Home Depot or a
piece of small diemeter pvc or cpvc marked with a sharpie
for the correct oil level. For best results and least
hassle, just forget the "ATF" and go with a good fork oil
unless you like to work for giggles instead of results. You
will be pleased with the result.

Lugnut

 

Ineed...then again it's not quiet fast enough to be threat now is
it? ;^)

 

Ineed...then again it's not quiet fast enough to be threat now is
it? ;^)

***************

The engine I took out of a scrapper I bought to break for spares could just
about touch 70 in favourable conditions, but there was the unmistakable
knocking of a fucked big end - they're needle roller bearings so complete
failure would be soon and catastrophic.

There was a crank in the box of bits that came with it and both big ends
checked out ok, but since rebuilding with that crank its never gone over 65.

I think the carbs are knackered too, but despite having scrapped about half
a dozen CB200s over the years I can't seem to find a better pair.

Although I did find a spare speedo at the back of the garage while looking
for something else.

 

Not really the best of engines, the CB200: the CB175 that preceded it
was better. Smoother, sweeter and (in my experience) faster, too.

And the CB175 had a decent TLS front brake. The first version of the
CB200 had that, too, and then they ditched it for that awful cable
thing.

 

IIRC the CB175 is 20bhp and the CB200 only 17.

I'd be more than happy to get hold of a 175 lump - the last 175 I bought had
a 200 lump in it, so there's no reason to expect the other way round
wouldn't fit.

Mine is an old version with TLS front brake.

The last cable-disk brake CB200 I had, I put the front fork assy from an
RD200DX on it - I had to pack the yolk clamps with strips cut from a Coke
can as the Yammy stanchion diameter was just enough smaller diameter that
the clamps closed without gripping tightly.

 

Didb't know that but it would explain a lot. I've owned three or four
CB175s and they'd all hit an indicated 80, whereas the CB200 would
struggle to see 75.

They're interchangeable, yes, but the parts aren't. Not like CD/CB175.
They changed a hell of a lot on the 200.

 

They changed pretty much everything - I think the clutch plates might be
interchangeable. Oh - and the spark plugs.