Fork oil weight

[Grandpa]

I use motorcycle 20 weight fork oil and it works fine on my 1100. Change it every two years or so.

[rikusa]

weight

Hey, I'm 6'2" and 195. Because of this thread I've stopped worrying about being a fat bastard. Thanks, Rik

[rustybronco]

Rik, you'd better! i'm 6'-1" 235lbs (did i forget to mention old too!)

[KGB]

Rik, you'd better! i'm 6'-1" 235lbs (did i forget to mention old too!)

Me too
50 in a couple of weeks..........

[mhardig]

y'all are lightweights

6'2", 350.

I'm hoping the more I ride the less likely I am to eat.

[JHawkins]

6'2", 350.

I'm hoping the more I ride the less likely I am to eat.

Good Luck!

The problem with riding more is burning more gas, then stopping for gas, then since your stopped, you might as well get something to drink and a quick snack before hitting the road again....... and then REPEAT!

I have an L model, so the process is condensed even more, about every 100 or 120 miles.

[rustybronco]

MY son rides yammerha 650 6-3 375 ish... 25 years young

kgb happy early 50!!! been a few for me

[bwringer]

At the GS rallies, it becomes apparent that we could put together a pretty good rugby club or maybe hand out tights and put on a wrestling show. Lot of big fellas for some reason...

Back to fork oil:

I haven't been able to find 20W fork oil for a while, so I use 15W mixed with 10% "motor honey". Motor honey is that really thick gooey yellow stuff you can put in an expiring car engine to thicken the oil just before you sell it. (DO NOT put it in a motorcycle engine!).

You can adjust the ratio of motor honey to fork oil to suit you. The motor honey seems to do a nice job of coating parts and reducing friction and stiction for noticeably smoother fork action.

It's very important to remember that the recommendation in the manual has a couple of problems:

1) Wear -- the damping passages in forks slowly wear over the years and miles, so you'll need somewhat thicker oil.

2) Fish and rice diet -- the original suspension specs were developed by Japanese factory test riders who weighed maybe 130 pounds maximum. Compare that to your average American (or Brit, Aussie, or Kiwi) GS rider (see above), and there's obviously a problem...

3) Heavier fork springs -- The original fork springs, pitifully weak to begin with (see point 2), degrade and collapse with time. Heavier new fork springs are mandatory on any GS, and thus you'll need heavier fork oil to provide proper damping and control.

[mhardig]

Speaking of fork springs

I have a 'donor bike" i dug out of a dumpster. It has a lot of good parts which I'm using to put together my bike. It had a pair of fork caps which were anodized aluminum, drilled and tapped for 1/8 npt, and in the 1/8 npt holes, a tire-type schrader valve. I assume this was meant to add (air? Nitrogen?) to the front forks, making them springier. Anyone ever see/use this? does it make sense, and is it worthwhile?

[tfb]

Are you kidding me? Honda sells fork oil in qt bottles and you need about 30cc or less per leg. How can any bike use an entire quart of fork oil and then some?? BTW a bottle of fork oil is NOT expensive, unless you're buying it a Sachs Fifth Avenue.

Errm, we're a long way from Louisiana or even Sachs Fifth Avenue here in Australia, and believe me when I say that the fork oil here is (1) expensive, and (2) in dumb-sized bottles.

"30cc or less per leg"? No, for a Katana GS(X)1100 you need 227cc in each fork leg.

If things are efficient and cheap where you are, then you're in luck, and we're not. :-D

Mike.

[rustybronco]

TFB what do you use or what is commonly used in the land down under?
for oil-fork

[tfb]

Well most folks just pay out for the 'genuine' fork oil, but I got tired of that, so 12 months ago I put in some 15W mineral engine oil, and it's been FINE.

10W is the recommended viscosity in the manual, but as my forks are old and the internals are a bit worn, I thought something slightly thicker would be the go. For my weight (slightly above average at 80kgs... not sure what that is in lbs), the front end is still a bit too firm, esp. when on the gas and you hit a set of bumps mid-bend. So next time I'll just put in some 10W engine oil and see how that goes.

The only time I think a 'proper' fork oil would be useful, is if you're really hammering along and the suspension starts to lose its zing due to the oil 'frothing'. Hopefully (and you would hope so, for the money) a dedicated fork oil would minimise this.

Just my 2 cents worth.

Mike.

[tkent02]

Interesting way to clean out old fork oil....

1. Drain nasty old oil.
2. Pour in some ATF, straight.
3. Ride on bumpiest road around, long enough to get the ATF heated up.
4. Drain nasty ATF.
5. Pour in More ATF.
6. Repeat steps 2 through 5 untill the ATF is no longer nasty.
7. And my plan is to use 45% ATF, 45 % 10w30 and 10% Motor Honey

[rustybronco]

mine is going to be 50% 20wt engine oil + 50% atf (7wt) = 13.5wt with the anti-foaming properties of atf.
tfb thanks for the information about using 15w oil for 12 months that's what i was wanting to know.
how about you using 40% 15w oil + 60% atf =10.2 w ?
on a side note 1kg =2.2lb

[tfb]

Well that's an interesting idea about adding ATF to oil to come up with (i) the desired viscosity, and (ii) anti-foaming properties.

What I would like to know is, will adding ATF to conventional engine oil really cut back the foaming?

I ask the question because, what if the foaming is related to the properties of the engine oil, regardless of what's in the ATF? In other words, ATF by itself doesn't foam because it has had a certain chemical component removed, whereas the oil foams because it hasn't had the component removed? In which case, see, mixing the ATF with the oil would just result in a combined product which foams regardless!

Now, I'm just asking the question. You guys could be on to something here, or you could not... it all depends on knowing why the ATF doesn't foam; does it have an additive, or does it have something subtracted?

Maybe one of our chemistry fellas could chime in on this one? I'll certainly look at using some ATF if it turns out to be the ticket to anti-foaming. And Rustybronco, my body weight in lbs looks positively scary -- I think I'll stick to kilos!

Mike.