Topic: Fork oil level question

[Sweep]

I have had a funny front end for a while and I finally got around to re-addressing my forks.  I rebuilt the forks and installed new progressive springs, which came with a piece of PCV for preload.  The assembled height with the spacer is roughly even with the top edge of the fork when uncompressed so I'm good there.

I followed the instructions that came with my new springs on filling up the forks and leaving 5.5 inches of space above the fluid but somehow the fluid seems pretty high to me once I put the springs back in.  There is precious little airspace there, less than an inch and when I try to compress the suspension in the garage, it ain't budging.  So I'm assuming I have too much fluid in there. 

I'm guessing I shouldn't see the fluid near the top with everything installed in the fork?  I'm thinking of just removing equal amounts with a turkey baster but I'd like to hear what I did wrong.

Thanks.

[wireman]

I put in 6 oz. and reused the old springs.  They were a little bouncy and I talked with my parts guy and he said to take and cut some pvc pipe and get it level with the top fork or just above.  He said they used to do that in the old days instead of buying new springs.  I tried it today but haven't got out to try if it helped.  Actually my shop manual said to put in 7oz.  But that seemed a little much. I've heard anywhere between 5.4 to 6.5 oz. being put in.  I can't figure out why you have no compression at all.  SORRY not alot of help.

[Sweep]

For all I know there was too much compression before and I'm just used to it.  Like most of us here I'm flying blind until I make a mistake and adjust.

[Sweep]

So if I'm right the oil is the damping but with too much the spring will not compress, I need a certain amount of air in there?

[MCRider]

So if I'm right the oil is the damping but with too much the spring will not compress, I need a certain amount of air in there?

The measuring from the top method is what the racer guys use, and you got those instructions from Progressive. I'll be setting up my legs soon and need to revisit this skill long dormant.

http://www.unitconversion.org/volume/cubic-centimeters-to-fluid-ounces-us-conversion.html

If your forks were bone dry, you should fill with the manual amount, usually 200 to 240cc depending on the model, around 7oz, not much.

The measuring down method is when you've got a fork with residual oil in it and you don't want to overfill, or fill unevenly. I'm pretty sure it includes having the springs and all hardware in the tube first. I'm doing some searches now to refresh my memory. But my guess is you have way too much oil in the forks.

http://www.kneedraggers.com/details/Motion_Pro_Fork_Oil_Level_Gauge--56-MP-28.html


here's a thread that confirms what i said about a clean dry fork vs one with residual in it.  No comments on springs in or out though. Also, the tubes should be vertical when making the measurement. Likely out of the trees unless you have an elaborate swing affair. 

Also, in my mind the measuring down, vs the measuring cup is really getting too obssessive for most street riders.

[MCRider]

No compression at all would almost have to mean they are hydraulic locked. Too much oil.

On the bouncy question: most of our old forks, the spring provides virtually all the control on compression. The oil provides rebound damping. So if the fork is bouncy there is likely not enough oil or too light weight to suit. If you increase the preload with spacers, I think they will just get bouncier.

[MCRider]

Here's a good DIY on fork oil. Not our bike, but many steps are similar. With good tips on improvised tools.
http://www.bluepoof.com/motorcycles/howto/svs_fork_oil/

[MCRider]

here's an interesting twist. For this bike, the springs are out and the forks are compressed to make the top down measurement.
http://www.motorcyclekb.com/Uwe/Forum.aspx/off-road/1858/How-do-I-check-KTM-fork-oil-level

[MCRider]

And this ends the discussion for me. From our own forum, April 2 2009: Read the last post.
http://forums.sohc4.net/index.php?topic=49083.0

So I will have a dry fork. I will use this procedure, springs out, fork compressed, pour in the amount from the manual, using highest cc amount of the range, pump it a little. Then measure down and post for posterity.

In my searches, I found that those that seemed to know were perfectly willing to experiment with amounts, +/- cc, weights, etc. And for casual riding, measuring down from the top is not necessary, just better.

To answer your question, if your fork was extended when you put your oil in and measured, you have too much oil. I was wrong though in that the springs should be out.

[coyotecowboy]

I just got my frontend back together tonight, and found out that 7.5 to 7.8 oz. that the Honda manual recommends is....



drumroll please.....


ONE CUP!!

made that easier!  And man does it ride better!

[MCRider]

I just got my frontend back together tonight, and found out that 7.5 to 7.8 oz. that the Honda manual recommends is....



drumroll please.....


ONE CUP!!

made that easier!  And man does it ride better!

Well isn't that con veeenient?  (church Lady)

A plastic baby bottle is marked off in cc s for any one who cares.

This is convenient too. http://www.pitposse.com/ramecup.html

[Sweep]

Thanks for all the info.  MCRider it's funny because the last time I actually used my baby's formula storage bottle with cc markings to the side.  The only problem is that with the addition of progressive springs and the fact that I think my forks are longer than stock (forgot to mention) I was looking for a more sure method.

[Sweep]

I see the mistake I made, I measured the 5 1/2 inches UNCOMPRESSED and I thought I read that in the instructions but I assume either they are wrong or I misread them.  Off to the garage to do this over!

[MCRider]

Thanks for all the info.  MCRider it's funny because the last time I actually used my baby's formula storage bottle with cc markings to the side.  The only problem is that with the addition of progressive springs and the fact that I think my forks are longer than stock (forgot to mention) I was looking for a more sure method.

Yes changing the springs changes things in that the newer springs often have more bulk to them taking the place of oil. All my searches led me to this conclusion. Any amount of oil is OK as long as its relatively near the original amount and that its even on both sides. Hence the measuring technique. Then you can add or subtract in increments with a syringe depending on ride feel.

The high performance guys are adamant about using the measuring down from top technique, but its as much to make them equal as to how much is in them. How much is personal preference within limits.

The length of the tube BTW, will have no effect on how much oil should be in them. Still use the stock amount. The extra air may give it some ride improvement. I'm using 2" over stock tubes with air caps, hoping to get some more adjustability. I'm going from a 19" wheel to a 17", and I'll slide them up the triples to maintain stock ride height +/-.

Have we determined what was locking yours up?

PS: I just looked at my Clymers and for oil it recommends ATF or 10w-30 motor oil. So essentially the oil to use is personal preference also. But it should be changed every 6000 miles or once a season (due to condensation/water pollution). I have been very bad about that over the years with my bikes.

[Sweep]

Well I took my coffee and went out into the garage and tackled it this morning.  The spray bottle idea is genius, I put a piece of tape 5 1/2" up the tube and sprayed the excess oil into the bottle.  Now my shocks seem better than ever, in fact completely different and correct, I should have used this method last time because I must have had way too little fluid in there.  Thanks for the info.

If the ride seems stiff I'll take out another inch of fluid but they do feel right.  I also have my shocks pulled up over the trees by a few inches and have clipons installed there.  Now I can move on the to fun stuff, wiring up my new horn and turn signals.

[MCRider]

Well I took my coffee and went out into the garage and tackled it this morning.  The spray bottle idea is genius, I put a piece of tape 5 1/2" up the tube and sprayed the excess oil into the bottle.  Now my shocks seem better than ever, in fact completely different and correct, I should have used this method last time because I must have had way too little fluid in there.  Thanks for the info.

If the ride seems stiff I'll take out another inch of fluid but they do feel right.  I also have my shocks pulled up over the trees by a few inches and have clipons installed there.  Now I can move on the to fun stuff, wiring up my new horn and turn signals.

Too little fluid?

[Sweep]

Well I took my coffee and went out into the garage and tackled it this morning.  The spray bottle idea is genius, I put a piece of tape 5 1/2" up the tube and sprayed the excess oil into the bottle.  Now my shocks seem better than ever, in fact completely different and correct, I should have used this method last time because I must have had way too little fluid in there.  Thanks for the info.

If the ride seems stiff I'll take out another inch of fluid but they do feel right.  I also have my shocks pulled up over the trees by a few inches and have clipons installed there.  Now I can move on the to fun stuff, wiring up my new horn and turn signals.

Too little fluid?

Yes, they were way too bouncy, compressible, and unstable on the highway.

[Sweep]

Also I don't remember what oil I used, not good.  I was in a rush to get the bike back together to test out the motor and figured I'd readdress the forks and other details later, as I am now.

[MCRider]

Also I don't remember what oil I used, not good.  I was in a rush to get the bike back together to test out the motor and figured I'd readdress the forks and other details later, as I am now.

Glad they're working now.

So this is your motor? '76 cb750K Wiseco 836|ape crank/head|Carillos|CR29s|Dyna 2k|Kerker
Pretty nice, bet its quick? Or you haven't had it running yet?

if you ever get real ambitious, put Race Tech Gold Valve cartridge emulators in your forks. You won't believe the difference. Like putting an 836 kit in your forks.   

[Sweep]

Also I don't remember what oil I used, not good.  I was in a rush to get the bike back together to test out the motor and figured I'd readdress the forks and other details later, as I am now.

Glad they're working now.

So this is your motor? '76 cb750K Wiseco 836|ape crank/head|Carillos|CR29s|Dyna 2k|Kerker
Pretty nice, bet its quick? Or you haven't had it running yet?

if you ever get real ambitious, put Race Tech Gold Valve cartridge emulators in your forks. You won't believe the difference. Like putting an 836 kit in your forks.   

Yes this is the bike, the motor and tranny are perfect so now I just work on other details.  I'm concentrating on brakes, controls, suspension, and electrics but the bike runs and I ride it for pleasure.  The bike is scary fast, made more so by the comparative weakness of the rest of the bike compared to the monster motor.  I've got so much money and time into this bike now that I have no problems spending $$$ on modern brakes and suspension upgrades as I can afford them. 

[MCRider]

Very nice. You mention tranny, what did you have done there?

[Sweep]

Very nice. You mention tranny, what did you have done there?

Oh nothing major but I did completely rebuild it and go over it to spec.  I replaced some gears and shift forks with better OEM pieces.  I also have a Barnett clutch and springs.

[MCRider]

Very nice. You mention tranny, what did you have done there?

Oh nothing major but I did completely rebuild it and go over it to spec.  I replaced some gears and shift forks with better OEM pieces.  I also have a Barnett clutch and springs.

I see. That second gear shift fork can wear over time. Results in second gear jumping out.

I've had mine undercut on the 1-2, 2-3, and 3-4 upshifts and the 3-2 downshift. (budget) by APE. Haven't installed it yet.

[Sweep]

Very nice. You mention tranny, what did you have done there?

Oh nothing major but I did completely rebuild it and go over it to spec.  I replaced some gears and shift forks with better OEM pieces.  I also have a Barnett clutch and springs.

I see. That second gear shift fork can wear over time. Results in second gear jumping out.

I've had mine undercut on the 1-2, 2-3, and 3-4 upshifts and the 3-2 downshift. (budget) by APE. Haven't installed it yet.

I with I did it now but I really was at my max expenditure at that point.  I have almost to qualms about pulling the motor to do it in the future.  I've done it before, just pull the motor turn it upside down and pull off the bottom of the crankcase.  The gears work well for now but once in a while in 3rd or 4th I forget which it will slip out if I haven't put it into gear with enough authority.

[MCRider]

Very nice. You mention tranny, what did you have done there?

Oh nothing major but I did completely rebuild it and go over it to spec.  I replaced some gears and shift forks with better OEM pieces.  I also have a Barnett clutch and springs.

I see. That second gear shift fork can wear over time. Results in second gear jumping out.

I've had mine undercut on the 1-2, 2-3, and 3-4 upshifts and the 3-2 downshift. (budget) by APE. Haven't installed it yet.

I with I did it now but I really was at my max expenditure at that point.  I have almost to qualms about pulling the motor to do it in the future.  I've done it before, just pull the motor turn it upside down and pull off the bottom of the crankcase.  The gears work well for now but once in a while in 3rd or 4th I forget which it will slip out if I haven't put it into gear with enough authority.

Yeah you may be in line for an upgrade, but like you say it can be done easily later.