?Fork oil
frogliver
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.
S'mee
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.
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.
S'mee
> On Jun 12, 8:15 am, "frogliver" <f_gli...@nospam.com> wrote:
>
> > 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,
>
> 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.
Not true, not true at all...
> The other reason was that ATF used to contain whale oil as a friction
> modifier.
Maybe in the 50's you stupid git.
> Importation of whale oil was banned later.
iirc that was in the 50's.
> 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.
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.
frogliver
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
"S'mee" <steven...@hotmail.com> wrote in message
news:9cc87617-b00a-49ee...@u20g2000pru.googlegroups.com...
`
> Does anyone know what Honda meant by "use ATF" back in '79? You know, like
> was it a Dexron thing, or some other standard?
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.
S'mee
> 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.
exactly that. They were giving the best answer they had to the issue
"what do we use for oil in the forks Akama?"
>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.
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.
> Does anyone know what Honda meant by "use ATF" back in '79? You know, like
> was it a Dexron thing, or some other standard?
Answered already.
S'mee
SNIP
What utter shite. YOu know fuck 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.
> 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.
LOL see you prove me right.
> Maybe there's an emulator kit for your machine. Also, look up the
> recommended fork oil weight on that website.
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.
The Older Gentleman
> 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.
No, they don't
> This traps air, which effectively increases the spring rate by adding
> an unwanted air spring.
No, it doesn't.
> My 1968 Yamaha 250 Single Enduro had special air valves in the fork
> caps that could be used to "burp" excess air trapped pressure.
So why don't all motorcycles have them now, genius?
> The motorcycle magazines accused Japanese motorcycle manufacturers of
> using "fish oil" in their forks,
So this is where you got 'whale oil' from? And whales aren't even
fish[1].
[1] They're insects.
--
BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple
Suzuki TS250ER GN250 Damn, back to six bikes!
Try Googling before asking a damn silly question.
chateau dot murray at idnet dot com
ian field
On Jun 12, 4:13 pm, "frogliver" <f_gli...@nospam.com> wrote:
> 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.
exactly that. They were giving the best answer they had to the issue
"what do we use for oil in the forks Akama?"
>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.
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.
S'mee
wrote:
SNIP
> 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.
<rolls eyes> fat lot of help that was...
ian field
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.
S'mee
wrote:
> "S'mee" <stevenkei...@hotmail.com> wrote in message
Ineed...then again it's not quiet fast enough to be threat now is
it? ;^)
ian field
***************
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.
The Older Gentleman
> 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.
ian field
"The Older Gentleman" <totallyde...@yahoo.co.uk> wrote in message
news:1jk3gyz.14tdytzl9q7r4N%totallyde...@yahoo.co.uk...
> ian field <gangprob...@ntlworld.com> wrote:
>
>> 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.
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.
>
> 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.
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.
The Older Gentleman
> IIRC the CB175 is 20bhp and the CB200 only 17.
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.
>
> 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.
They're interchangeable, yes, but the parts aren't. Not like CD/CB175.
They changed a hell of a lot on the 200.
ian field
> ian field <gangprob...@ntlworld.com> wrote:
>
>> IIRC the CB175 is 20bhp and the CB200 only 17.
>
> 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.
>
>>
>> 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.
>
> 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.