spydigtconv149
Registered
Hey guys and girls, I drag race my gen 1. I am in the process of lowering my internals of my forks. My question is could I use a motor oil instead of "fork oil"?
oil in forks
- Thread starter spydigtconv149
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spydigtconv149
Registered
Can I ask why?
My two cents are yes you can. My other two cents are why would you? (Two bottles of fork oil are cheap compared to the effort to take the forks apart.) The characteristics of the fork would basically be an unknown until you tested them. At that point if they didn't perform well you'd have to redo them. Not worth the effort if you ask me.
Stolen from another forum. It's an interesting read.
************************************************************
Subject: Oil Viscosities
Regarding the discussion of oil weight for front forks, I saved the
following post from the observed trials list because it addresses this very
question, and because I thought it was kind of cool that someone cared
enough to sit at his workbench with a stopwatch and run thickness tests on
all kinds of oils. You'll see there's a big difference in different kinds of
ATF.
Jim Winterer
St. Paul, Minnesota
Date: 16-Feb-1999 06:19pm CST
This is a reissue of previous info with some additions. The below is
valuable in evaluating what oil to use in forks (to set dampening speed)
and what oil to use in 2-cycle motor gearboxes (to affect clutch
performance), or just plain interesting to technonerds.
I wrote an e-mail some months ago describing my home made viscosity
meter, consisting of 50cc of oil passed through a vented plastic
container with a .140" orifice at bottom. Time to drain being the output
of the test. I was at the time measuring oil viscosity for gearbox use
to find a thin oil to eliminate drag with my Scorpa/Rotax clutch. Dexron
II ATF did just that.
My method is rough and not standard. The units are not Centisokes, but
seconds to empty with home-made set-up, similar in concept to standard
viscosity meters. My method is a handy comparative tool for determining
comparative oil viscosity at room temperature. I also do not care about
high temperature viscosity, or even viscosity index (which considers the
difference between high and low temp viscosities. Most two stroke gear
box and fork applications are relatively low temp, so one number is
goodnuff.
The bottom line is you simply cannot trust SAE weight range numbers as a
way to compare oil thickness. The SAE system is NOT a measure of
viscosity, but rather a range of viscosities. We are being robbed of
important information by oil re sellers, particularly suspension in oils,
by their not showing their actual viscosities. Sure makes it hard to
tune suspension or alter clutch characteristics! The SAE way of looking
at things allows sale of a 2.5 weight oil that is thicker than a 5 weight
oil! But who cares. That fellow who puts in Bel-Ray High Perf. Fork Oil
7 weight oil after taking out his Bel-Ray High Perf. Fork Oil 10 weight
oil will swear up and down his forks move quicker because it "says so
right there on the bottle!" Also, that fellow will also swear up and
down that his clutch drags less with motor oil instead of gear oil
because "them there numbers on the bottle is smaller." Well, gear oils
use a different SAE scale. Now that's really intuitive!
My results. Shorter time means thinner viscosity. There are some
surprises in there.
Gear Related:
---------------------
Stihl Chainsaw Bar Oil 2006 97s
Valvoline 85W140 Gear Oil 83s
Valvoline 10W40 Motor Oil 57s
Unilube Synthetic 75W-90 Gear Lube 50s
Belray Gear Saver 80 weight 50s
Citgo Chrysler Spec 7176 ATF 41s
Valvoline Dexron III ATF 26s (a great option for
eliminating clutch
drag in trials bikes)
Suspension:
---------------------
Bel-Ray High Perf. Fork Oil 10 weight 21s (same oil as 7 weight)
Bel-Ray High Perf. Fork Oil 7 weight 21s (same oil as 10 weight)
PJ1 Fork Tuner H.V.I. 5 wt. 16s
Bel-Ray High Perf. Fork Oil 5 weight 14s
Golden Spectro 85/150 2.5 wt. Very Light 13s (a petroleum/synthetic
cartridge fork oil)
Stock Paioli Fork Oil from Factory, Used 12s
Honda/Showa SS7 shock oil 5 weight 12s
Fox Racing Oil 5 weight J26 12s
Maxima Zero-Fade Light Shock Fluid 5 wt. 11s (white bottle)
Maxima High-Perf. Light Shock Fluid 5 wt. 11s (black bottle)
Stock oil out of a Boge shock 11s
Isopropyl Rubbing Alcohol 9s
Justice for Corrupt Powerful Politicians 11.76 Gigaseconds
Note how the 10 and 7-weight Bel-Ray fork oil is the exact same oil,
while the 5 weight is not. That's right, the exact same oil! Cheating?
Not exactly. The weight of an oil is not the viscocity but rather the
SAE viscocity RANGE, so you can have overlap in the ranges, and
legitimately can sell two different weight oils of the same viscocity,
though this is misleading. Because oil is highly a subjective
experience, like spark plugs and the myths surrounding them, there will
be fellows who will swear their forks move faster with that 7 weight
verses 10, even though it's the exact same oil! Too bad the actual
viscocity numbers of oils are hardly ever listed on the bottles. On rare
occasion you will get the SAE weight expressed as the lower and higher
viscocity numbers. Case in point: Golden Spectro Synthetic/Petroleum
Cartridge Fork Fluid. They say on the bottle:
85/150 is equivalent to 2.5 (light) fork fluid for SHOWA forks.
125/150 is equivalent to 7.5 (medium) fork fluid for KAYABA forks.
Thus you see in the above statements the association of viscocity numbers
with their corresponding ranges. Note how the upper limit of 2.5 weight
is the same as the 7.5 weight? Confusing, isn't it! Perhaps I should
buy only Golden Spectro, as they at least are up front with what's in the
bottles.
Note also how the higher gear lube weight is thinner than the motor oil
of a lower weight number. That's because motor and gear lubes use a
different scale, though they are still called "weights". It is also why
motor oil can cause more clutch drag than a "heavier" gear lube. To
those on the 650 list: Obseved Trials riders use their clutches almost
like an automatic transmission, especially when stopped or barely moving.
Clutch drag is thus a bad thing, as it tends to make you want to roll
forward when you don't want to. It upsets contol while balanced and
makes shifting while stopped and balanced very hard and notchy.
Back to the forks. Conclusion. I used 300cc of the Maxima shock oil in
the rebound side, as the viscocity was the closest of the available oils
I had. It turned out to be right upon riding the bike later in the day.
Shock oils, however, get sticky when they dry out. Hopefully that won't
have any bad effect on the fork seals. It should not, as I have long
used shock oils in forks with no harmful effects. For years I used Showa
(now Honda) 5 weight shock oils in forks. Shock oils tend to be very
light, therefore conducive to most trials bikes with their fast
suspension speeds. Shock oils also tend to be of higher quality as the
application is much more severe than that of forks.
Have fun digesting this info.
Chris Johnson, Engineering Director,
College Park Industries, Inc.
Stolen from another forum. It's an interesting read.
************************************************************
Subject: Oil Viscosities
Regarding the discussion of oil weight for front forks, I saved the
following post from the observed trials list because it addresses this very
question, and because I thought it was kind of cool that someone cared
enough to sit at his workbench with a stopwatch and run thickness tests on
all kinds of oils. You'll see there's a big difference in different kinds of
ATF.
Jim Winterer
St. Paul, Minnesota
Date: 16-Feb-1999 06:19pm CST
This is a reissue of previous info with some additions. The below is
valuable in evaluating what oil to use in forks (to set dampening speed)
and what oil to use in 2-cycle motor gearboxes (to affect clutch
performance), or just plain interesting to technonerds.
I wrote an e-mail some months ago describing my home made viscosity
meter, consisting of 50cc of oil passed through a vented plastic
container with a .140" orifice at bottom. Time to drain being the output
of the test. I was at the time measuring oil viscosity for gearbox use
to find a thin oil to eliminate drag with my Scorpa/Rotax clutch. Dexron
II ATF did just that.
My method is rough and not standard. The units are not Centisokes, but
seconds to empty with home-made set-up, similar in concept to standard
viscosity meters. My method is a handy comparative tool for determining
comparative oil viscosity at room temperature. I also do not care about
high temperature viscosity, or even viscosity index (which considers the
difference between high and low temp viscosities. Most two stroke gear
box and fork applications are relatively low temp, so one number is
goodnuff.
The bottom line is you simply cannot trust SAE weight range numbers as a
way to compare oil thickness. The SAE system is NOT a measure of
viscosity, but rather a range of viscosities. We are being robbed of
important information by oil re sellers, particularly suspension in oils,
by their not showing their actual viscosities. Sure makes it hard to
tune suspension or alter clutch characteristics! The SAE way of looking
at things allows sale of a 2.5 weight oil that is thicker than a 5 weight
oil! But who cares. That fellow who puts in Bel-Ray High Perf. Fork Oil
7 weight oil after taking out his Bel-Ray High Perf. Fork Oil 10 weight
oil will swear up and down his forks move quicker because it "says so
right there on the bottle!" Also, that fellow will also swear up and
down that his clutch drags less with motor oil instead of gear oil
because "them there numbers on the bottle is smaller." Well, gear oils
use a different SAE scale. Now that's really intuitive!
My results. Shorter time means thinner viscosity. There are some
surprises in there.
Gear Related:
---------------------
Stihl Chainsaw Bar Oil 2006 97s
Valvoline 85W140 Gear Oil 83s
Valvoline 10W40 Motor Oil 57s
Unilube Synthetic 75W-90 Gear Lube 50s
Belray Gear Saver 80 weight 50s
Citgo Chrysler Spec 7176 ATF 41s
Valvoline Dexron III ATF 26s (a great option for
eliminating clutch
drag in trials bikes)
Suspension:
---------------------
Bel-Ray High Perf. Fork Oil 10 weight 21s (same oil as 7 weight)
Bel-Ray High Perf. Fork Oil 7 weight 21s (same oil as 10 weight)
PJ1 Fork Tuner H.V.I. 5 wt. 16s
Bel-Ray High Perf. Fork Oil 5 weight 14s
Golden Spectro 85/150 2.5 wt. Very Light 13s (a petroleum/synthetic
cartridge fork oil)
Stock Paioli Fork Oil from Factory, Used 12s
Honda/Showa SS7 shock oil 5 weight 12s
Fox Racing Oil 5 weight J26 12s
Maxima Zero-Fade Light Shock Fluid 5 wt. 11s (white bottle)
Maxima High-Perf. Light Shock Fluid 5 wt. 11s (black bottle)
Stock oil out of a Boge shock 11s
Isopropyl Rubbing Alcohol 9s
Justice for Corrupt Powerful Politicians 11.76 Gigaseconds
Note how the 10 and 7-weight Bel-Ray fork oil is the exact same oil,
while the 5 weight is not. That's right, the exact same oil! Cheating?
Not exactly. The weight of an oil is not the viscocity but rather the
SAE viscocity RANGE, so you can have overlap in the ranges, and
legitimately can sell two different weight oils of the same viscocity,
though this is misleading. Because oil is highly a subjective
experience, like spark plugs and the myths surrounding them, there will
be fellows who will swear their forks move faster with that 7 weight
verses 10, even though it's the exact same oil! Too bad the actual
viscocity numbers of oils are hardly ever listed on the bottles. On rare
occasion you will get the SAE weight expressed as the lower and higher
viscocity numbers. Case in point: Golden Spectro Synthetic/Petroleum
Cartridge Fork Fluid. They say on the bottle:
85/150 is equivalent to 2.5 (light) fork fluid for SHOWA forks.
125/150 is equivalent to 7.5 (medium) fork fluid for KAYABA forks.
Thus you see in the above statements the association of viscocity numbers
with their corresponding ranges. Note how the upper limit of 2.5 weight
is the same as the 7.5 weight? Confusing, isn't it! Perhaps I should
buy only Golden Spectro, as they at least are up front with what's in the
bottles.
Note also how the higher gear lube weight is thinner than the motor oil
of a lower weight number. That's because motor and gear lubes use a
different scale, though they are still called "weights". It is also why
motor oil can cause more clutch drag than a "heavier" gear lube. To
those on the 650 list: Obseved Trials riders use their clutches almost
like an automatic transmission, especially when stopped or barely moving.
Clutch drag is thus a bad thing, as it tends to make you want to roll
forward when you don't want to. It upsets contol while balanced and
makes shifting while stopped and balanced very hard and notchy.
Back to the forks. Conclusion. I used 300cc of the Maxima shock oil in
the rebound side, as the viscocity was the closest of the available oils
I had. It turned out to be right upon riding the bike later in the day.
Shock oils, however, get sticky when they dry out. Hopefully that won't
have any bad effect on the fork seals. It should not, as I have long
used shock oils in forks with no harmful effects. For years I used Showa
(now Honda) 5 weight shock oils in forks. Shock oils tend to be very
light, therefore conducive to most trials bikes with their fast
suspension speeds. Shock oils also tend to be of higher quality as the
application is much more severe than that of forks.
Have fun digesting this info.
Chris Johnson, Engineering Director,
College Park Industries, Inc.
Salty
Registered
More so I would recommend running a stiffer oil than factory, talk to your local motorcycle shop about running a race weight oil in your forks. I switched my coil size on my gen 1 and switched to a race grade fork oil and found it a lot more to my liking over the squishy stock oil/coil combo.
spydigtconv149
Registered
This is what I feel like motor oil will do
I use Dexron III ATF.
There is much debate about this. Back in the day, all the MC forks contained ATF. There was no such thing as special fork oil. I changed the fork seals on my Hayabusa a couple years ago and refilled with Dexron III ATF. I've gone about 11000 miles like this. Nothing has blown up. I don't race... I just tour.
There is much debate about this. Back in the day, all the MC forks contained ATF. There was no such thing as special fork oil. I changed the fork seals on my Hayabusa a couple years ago and refilled with Dexron III ATF. I've gone about 11000 miles like this. Nothing has blown up. I don't race... I just tour.
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