Topic: Forking Motor Oil

[Retro Rocket]

if you've never heard of increasing or decreasing the amount of oil in forks to adjust its ride im dumbfounded mick?its a normal thing to do.

Gday Dave, I've heard of adding more but never less, unless you've already added more.  I used to hang with quite a few racers and our shop had a resident racer as well {early GSXR750},  I also have a friend thats a suspension guru, and they always changed viscosity to soften the suspension, thats if the suspension adjustment wouldn't give the desired results. I've always been told to never use less fluid, never questioned it at all mate...

[dave500]

well maybe you should've questioned it,its a common thing im afraid,im sure a google search on fork oil level altering will net anyone interested in trying it out a bit of an education.

[Retro Rocket]

well maybe you should've questioned it,its a common thing im afraid,im sure a google search on fork oil level altering will net anyone interested in trying it out a bit of an education.

Dave, less oil in the front suspension means more travel, so unless you know exactly what you are doing you run the risk of bottoming out, I've had this happen and its not good, i reckon it could actually break your wrists if it happened hitting a pot hole, I did it going into my driveway and it hurt like hell, I cleaned out the forks and changed my oil {stock amount} and added a couple of small spacers {washers}and it made a huge difference.  Why question it when its coming from people that race successful race bikes...   It may be common with dirt bikes..?  They have far more travel. Its far more important to know how much travel your suspension is supposed to have and add fluid until you get the recommended number...  Unless you are experienced with suspension and know how to measure travel accurately, I wouldn't recommend reducing oil levels at all..

[dave500]

#$%* man im not talking like 50%less here!,has this never been discussed in the high performance threads?i don't know I rarely look in there.

[Retro Rocket]

#$%* man im not talking like 50%less here!

Yeah, I know, my reasoning is that, if you don't know where the suspension bottoms out, why would you even do it ? a slightly thinner oil will be easier and is the recommended way of doing it..  Do you know how much more travel there will be if you remove 5mm of oil level..?

[dave500]

well #$%* if it bottoms out add more,try braking #$%* hard and see how much it dives?maybe this isn't for the faint hearted?you gotta trial and error,i didn't like how stiff mine seemed for me with atf,so I lowered the level a little bit by bit until I liked it,doesent bottom out and im not buying over priced fork bloody oil,your sort of altering the air cushion on top of the oil,guys always seem to want to buy new springs and are still running the book listed oil amount,some are still not happy with the ride even with lighter oil,try using SLIGHTLY less oil,if your using volume measurements try perhaps 15ml less?

[Retro Rocket]

well #$%* if it bottoms out add more,try braking #$%* hard and see how much it dives?maybe this isn't for the faint hearted?you gotta trial and error,i didn't like how stiff mine seemed for me with atf,so I lowered the level a little bit by bit until I liked it,doesent bottom out and im not buying over priced fork bloody oil,your sort of altering the air cushion on top of the oil,guys always seem to want to buy new springs and are still running the book listed oil amount,some are still not happy with the ride even with lighter oil,try using SLIGHTLY less oil,if your using volume measurements try perhaps 15ml less?

Depending on the bike, 15mm could decrease travel by the same amount {15mm}thats quite a lot, Dave, don't get upset mate, Noobs shouldn't be doing sh1t like this, thats why we are commenting on it. You DON"T want to have your bike bottom out to find that your oil level is too low, believe me , if it happened at speed it could completely remove your hands from the bars, thats how violent it is, its like belting an iron bar into the concrete, it jars severely, you've obviously never had it happen..?  I agree, its not for the faint hearted or the novice, thats exactly why i'm saying not to do it.    Now shut up and have a fcuking beer, its too bloody hot ....

[dave500]

im not upset mick,just cracked a beer,there is nothing wrong with running a LITTLE lower oil than what the book states,novices have to learn sometime,you can hit a pot hole and have the same effect as bottoming out without actually bottoming out,you can hit a curb square on and its the same,you wont bottom out but itll feel like it has,you can bend bars doing it and not bottom out.

[ken65]

ive only ever changed the viscosity to  change the damping not the level, The bloke at RAD is a font of knowledge and hes helped me a couple of times. But hey thats just what ive experienced.. Having said all that im not an expert , but have to say i  serviced my fj forks a couple of weeks ago, wow , what a change a good clean and fresh oil makes......sometimes i think people over analyse the setup... hydraulics is hydraulics.     

[750cafe]

well maybe you should've questioned it,its a common thing im afraid,im sure a google search on fork oil level altering will net anyone interested in trying it out a bit of an education.

Well then, why not post some links? If it is such a common thing to do, you should have no problem whatsoever finding someone's blog perhaps even your own. 

Eric

[Retro Rocket]

you can hit a pot hole and have the same effect as bottoming out without actually bottoming out,you can hit a curb square on and its the same,you wont bottom out but itll feel like it has.

Dave, it may bend your bars mate but from what you've written you've never had a fork bottom out, there's nothing like it, i've hit some very big pot holes, I hit a huge pot hole near Ballina, pissing down rain at around 2 oclock in the morning, enough to shoot me across the road in front of an interstate bus and into a cane paddock, A guy in a Porsche hit the same pot hole and rolled his car {same night}, thats the biggest pot hole i've ever hit and still felt nothing like the fork bottoming out, I bottomed out braking reasonably hard going into my driveway on the sunshine coast, i had almost stopped but the suspension was already loaded, it hurt like hell and i thought i may have broken my wrists....It felt like being dropped on concrete from about 10 feet upside down with your elbows locked out I know hitting a pot hole sucks but as long as you've got some suspension left, it doesn't matter what you hit, it doesn't feel like bottoming out, you'll know when it happens and its worse under brakes... .....

[gregripko]

I personally will stick with stock amount and just change the weight depending on the feel I'm attempting to achieve.... Been busy working with an occasional ride here and there

[dave500]

well maybe you should've questioned it,its a common thing im afraid,im sure a google search on fork oil level altering will net anyone interested in trying it out a bit of an education.

Well then, why not post some links? If it is such a common thing to do, you should have no problem whatsoever finding someone's blog perhaps even your own. 

Eric

you too #$%*ing lazy eric?

[dave500]

yeah just use the stock amount gregripco,we cant you have you bottoming out all over the place like mick,and heres a link for eric.

http://lmgtfy.com/?q=http%3A%2F%2Fwww.4strokes.com%2Ftech%2Fktm%2Fforkoil.asp

[750cafe]

well maybe you should've questioned it,its a common thing im afraid,im sure a google search on fork oil level altering will net anyone interested in trying it out a bit of an education.

Well then, why not post some links? If it is such a common thing to do, you should have no problem whatsoever finding someone's blog perhaps even your own. 

Eric

you too #$%*ing lazy eric?

NOPE. It is NOT MY JOB to DEFEND YOUR incorrect statement.

The forks have a piston the displaces the required amount of fluid through orifices to dampen the piston travel. If it is sucking air, it is NOT GOING TO WORK!

Have a great time with the harsh ride on your bikes. 


Eric

[750cafe]

Just think about this as it is incredibly EASY to understand.
If your rear shocks bleed oil do they not then only rely on the springs? Thus the pogo stick ride... NO DAMPENING!
Now, isn't that simple enough?

Eric

[Duke McDukiedook]

Does a harder tire vibrate more?

I have noticed harder durometer rubber tends to transmit vibrations and bumps more.

[Duke McDukiedook]

I personally will stick with stock amount and just change the weight depending on the feel I'm attempting to achieve.... Been busy working with an occasional ride here and there

I broke down and bought a plastic graduated cylinder from the local hobby/science shop. Was a couple of bucks and I knew I would use it a few times when I need to be accurate within 5-10ml.

[dave500]

well post a link eric to anything strictly against using a lower oil level?im enjoying my softer ride thanks,(jeeze what a grouch!)

[750cafe]

Sorry Dave the term is not grouch it is called Mechanical Engineer. 
Who do you thinks designs these things??? Flying monkeys?

Eric

[Retro Rocket]

yeah just use the stock amount gregripco,we cant you have you bottoming out all over the place like mick,and heres a link for eric.

http://lmgtfy.com/?q=http%3A%2F%2Fwww.4strokes.com%2Ftech%2Fktm%2Fforkoil.asp

Sorry Dave, you missed my point...

[dave500]

still waiting on your link eric,i guess you didn't like what you read in any of mine?

[Retro Rocket]

Dave, I read through those links you posted and lots were about dirt bikes with far more suspension travel than our bikes, the only one i read that was about road bikes was about an SV650 and it said what i said, reducing oil levels reduced suspension travel, it was almost MM perfect, 3mm less oil gave 3mm less travel and so on, that guy was trying to get the recommended travel for his bike...

This one from your link says it all....

The real reason for setting the fork’s oil level is to achieve a certain air chamber size and to maintain tuning consistency, but most of all because of the way a sealed fork system works. If the oil level is set correctly, after about 1/3 of a fork’s total suspension stroke (or travel) there should be more air pressure inside the fork than there is fork spring force (or spring tension). In other words, you could remove the springs after 1/3 of the fork’s stroke and you wouldn’t miss them. At this point, the fork relies on air pressure to control the action and to resist bottoming.

Exact control of the air chamber volume in each fork leg is important. Equal air pressure in both legs achieves full benefit from the system. As little as 5mm (1/4 inch) change in fork oil level (or air chamber size) will affect the way your fork feels, controls action or resists bottoming. It can be that critical.

And thats also for a KTM dirt bike, the underlined sections are exactly what i'm talking about...

[dave500]

so you can infact use lower than the manual spec oil level?like I said not 50% less or such,and it doesent matter brand or road or dirt,show me where you must never ever use less than the spec level?most manuals say do not overfill!pretty feeble argument against never using less fork oil so far.

[strynboen]

vhen do you afterfill  engine oil ??


vait to it reacth at buttom line or,, vhen it goes under the mittel of the marked areia.?

.it dont make any difference..at long at it not komes under the lowest marked..but the oil gets to hot..running at low marked...some says..as there are less volume oil to cool..

.war goes on...