2013 V7 - Fork Oil Capacity?

[cmgies]

Looking around on the site I couldn't seem to find the approximate amount of fork oil that the 2013 V7's take.  Any thoughts?  I'm in the middle of a front end upgrade and want to be ready with the fork oil for when the parts arrive.

Thanks!

[guzzisteve]

150mm below edge, tube extended

[cmgies]

150mm below edge, tube extended

Now I'm really confused.  I had read about how to do this with the measurement method, but it seems to me everything I have read, including the shop manual, says that you should have the fork compressed when measuring the oil level.

It says "Oil level (from sleeve rim, without the spring and with the stem at the end of the stroke) 150 mm.

[drlapo]

Damn that's a confusing statement
Every bike I've worked on, except bikes in the 60a and early 70s, measure the air gap with the tube compressed w/o spring
The manual says 150mm , 6inches and I just assumed that is with the tube compressed

[ohiorider]

My 2003 Bonneville fork oil was measured with spring removed and fork compressed.  Leave it to Guzzi to say 'at the end of the stroke,' but then not defining which end, extended or compressed. 

[malik]

From memory, the 150mm air gap equates to around 400ml, each leg. So a 1 liter bottle does the job. Do they sell fork oil by the liter in your neck of the woods? I am about to confirm that soon, the oil in the Special feels like it needs refreshing.

I can't remember whether the tube was pushed in or pulled out. I will have to check the carious instructions I followed, because whatever I did, it worked a treat.

[drlapo]

MG recommends 5-20 motor oil for the forks or 7.5 hydraulic fluid (fork oil)
I remember that early long travel USD forks on some MX bikes used 5-20 oil successfully

[pyoungbl]

Remember that the air gap is part of the progressive resistance of the suspension.  If you measure air gap with the fork compressed and allow 150mm air gap you will have a huge air gap to compress when everything is back together and the forks extended.  In other words, you'll only get about a 2:1 or 3:1 compression ratio...not enough to make much difference.  The thing is that you don't want so little air gap that the forks are locked up before full travel.  I settled on 130mm air gap as best for me.  Suspension settings are on the order of a black art, there are guidelines but they are just a reference point.  Oh, and I'm NOT a suspension expert.

Peter Y.

[Kev m]

Reviving this old thread.

Drained the fork oil on my 2013 V7 Stone w/ Kafia forks yesterday.

During disassembly I removed the spring, compressed the forks and measured the distance to the top of the fluid. It measured at 6.5" which is MUCH lower than spec (120 mm +/- 1.5mm / 4.72" +/- 0.06" for Kafia forks, the Marzocchi spec is 150 mm / 5.9").

After overnight draining I'm measuring that as only 350cc of oil.

I'm a little worried that filling it ALL the way up to spec 120 mm might be too much.

Thoughts?

[Kev m]

This thread suggests 400cc would equal the Marzocchi spec of 150 mm

https://wildguzzi.com/forum/index.php?topic=82139.0


I don't want to drastically overfill my forks. If they were working well enough at ~160-165mm of fork oil height then shouldn't they continue to work well at that height?

Also after installation I can pretty easily add more fluid if I want to, but I won't be able to easily remove it at that point if that makes sense.

I'm thinking I should match what I took out or increase it very slightly - maybe 400cc and match the 150 mm spec?

[Kev m]

OK, I'm going to answer my own question in the hope it helps someone else.

I tried filling with 400cc each, but found that the level was WAY TOO HIGH - like only a 95 mm air gap (no spring, fork compressed).

So I attached a length of tubing to a syringe and cut it to 130 mm (I figured I'd try a slightly larger air gap than spec) and drew out approximately 25 cc of fluid from each fork.

Meaning had I filled it with 375 cc instead of 400 I probably would have been much closer to spec. Though I guess if one was really looking for a 120 mm gap that 400 works just as well if you're drawing down to the proper level.

Looking at how drastically 25 cc or 50 cc of fluid changes the level got me thinking. I wonder how much fluid was still left on the spring and spacer when I pulled them before measuring what I drained? I bet measuring and matching isn't a good technique with forks because it is tough to compensate for how much is left behind on other components.

And I wonder to how much closer to actual air gap spec my forks really were filled in the first place. I bet it wasn't nearly as far from spec as I first thought. Maybe even filled completely to spec. Though it is interesting that what I actually drained from each fork measured almost exactly 350 cc.

* shrugs *

Will report back in a few weeks when I get it back on the road and test this fork fluid type/viscosity/level

Liqui-Moly 10W fork fluid / Kafia forks / 130 mm air gap.

Kev

[Kev m]

Hey since I'm having a great conversation by myself I wanted to address one more point that was debated here and in other smallblock threads:

"How to measure air gap when setting up a smallblock fork?"

The question is fork tube extended upward of compressed into the lower.

Answer - COMPRESSED into the lower.

Explanation:

As noted earlier after removing the cap, spacer, and spring from each of Kafia fork I compressed the tubes and measured air gap. Even compressed the measurement was greater than the gap provided by the OEM.

Now these forks were factory filled and never leaked so we may want to question the factory spec, but there's no question that the spec must therefore have been to measure compressed. Because if you were to fill it to factory spec with the fork extended you would be using significantly more fluid than you drained.

Oh and to that point, trying to double check myself last night I scoured the usual Guzzi sources looking for info. The one thing I DID find was a post from Todd on Guzzitech. Shortly after draining a set of (then new) Kafia forks back in Dec 2013 he measured ~12 oz / 354 cc of drained oil, which is almost exactly the amount I measured (350 cc) from both of my forks. And the amount that gave a ~160 mm air gap.

I kinda wonder if the factory didn't set up, at least the early Kafia forks, with the same 150 mm air gap they were setting up the Marzocchi forks with in the same period of time.

10 cc could account for the amounts sticking to and wiped off the spacer and spring etc. And damn but wouldn't that sound like something that factory would do. Of course I kinda would have expected Kafia and Marzocchi to just provide the factory with while assembled forks so who knows.

It makes me wonder if that was one of the reasons I didn't hate the front end on that bike even stock when others really complained it was too harsh.

Stay tuned for more reports this spring we're I finally test it out.

[Bulldog9]

Kev, did you measure the air gap with the tube extended before draining?

As I said on ADV I'm almost positive when I swapped the fork springs on the MYS I measured the airgap with the forks extended and oil was close to the expected (110-120), but it could have been compressed......


Just checked my Service Notes.

Official Moto Guzzi Spec and Procedure (from V7 II Service Station Manuals)

Fork oil type: AGIP Fork 7.5W (or equivalent SAE 7.5W fork oil; some manuals allow SAE 5W or 20W as alternatives depending on climate/ride preference).

Air gap specification: Typically 150 mm (from the sleeve/outer tube rim to the oil level, with spring and preload spacer removed). The level must be identical in both legs for balanced handling.

Measurement position: Forks fully extended (stanchion/tube pulled out to maximum, fork leg upright and unloaded). This is the standard for air gap measurement on conventional right-side-up forks like those on the V7 II.
The manual states: Measure the air gap "from sleeve rim, without the spring and with the stem at the end of the stroke" — interpreted in context as extended position (full extension/end of outward stroke).

Do not measure compressed — that would give a falsely high oil level reading (smaller air gap) and lead to overfilling, which can cause harsh bottoming or fluid blowout.

Step-by-Step Fork Oil Level Procedure (per Manual)

Remove the fork cap, spring, and any preload spacer.
Ensure the fork leg is fully extended (bike on center stand with front wheel off ground, or fork removed and held upright).
Pump the fork a few times after initial fill to release air bubbles and fill internal passages.

Wait a few minutes for oil to settle.

Insert a ruler, dipstick, or fork oil level gauge straight down the tube (keep it vertical/upright).
Measure the air gap from the top rim of the outer sleeve to the oil surface — adjust by adding or sucking out oil to reach spec (e.g., 150 mm). Reinstall spring/spacer/cap, torque to spec, and test ride to confirm feel.

Why Extended? Compressed measurement is common on some inverted (USD) forks or older designs, but not for the V7 II's conventional telescopic forks. Extended ensures the full volume is accounted for, preventing issues like insufficient air space for compression or excessive pressure.

So I don't Know............. I do know that when Martin and I did Larry's Matris Fork kit at Bills a couple years ago, we measured the air gap with forks extended.

[Kev m]

Though I didn't specifically MEASURE the air gap with the fork extended I did peer into the tube and I'm but sure I could even SEE the level with it extended.

Your logic above claiming that measuring with it compressed would lead to overfilling is backwards. Extending the fork tube effectively increases volume (pulling the mounting point upward 130 mm of suspension travel from the top of the fluid). So if you use air gap to determine volume you will fill with much more oil to make the air gap in spec with the fork extended.

Now couple that with the fact that I've confirmed by at least one other source that my volume drained was correct/typical for a 2013 Kafia V7 fork AND the fact that I measured with the fork compressed before draining as well.

The only logical conclusion is that measuring with the fork extended would lead to overfilling and the use of more fluid.

But I have no explanation why you wouldn't have run into trouble assuming your notes are correct and the forks on the Stornello are similar/same.

A few other techs/riders posting on the adv thread agree with my recollection that compressed is the standard method in the industry and the correct way to read the otherwise ambiguous Guzzi manual translation.

* Shrugs *

[Bulldog9]

Though I didn't specifically MEASURE the air gap with the fork extended I did peer into the tube and I'm but sure I could even SEE the level with it extended.

Your logic above claiming that measuring with it compressed would lead to overfilling is backwards. Extending the fork tube effectively increases volume (pulling the mounting point upward 130 mm of suspension travel from the top of the fluid). So if you use air gap to determine volume you will fill with much more oil to make the air gap in spec with the fork extended.

Now couple that with the fact that I've confirmed by at least one other source that my volume drained was correct/typical for a 2013 Kafia V7 fork AND the fact that I measured with the fork compressed before draining as well.

The only logical conclusion is that measuring with the fork extended would lead to overfilling and the use of more fluid.

But I have no explanation why you wouldn't have run into trouble assuming your notes are correct and the forks on the Stornello are similar/same.

A few other techs/riders posting on the adv thread agree with my recollection that compressed is the standard method in the industry and the correct way to read the otherwise ambiguous Guzzi manual translation.

* Shrugs *

Being that you have everything apart, why not measure it BOTH ways?  Extended and compressed to see if there is a correlating change and what the difference is?  I note that Guzzi Steve mentioned above that it is measured with Fork Extended.

 

[Kev m]

Being that you have everything apart, why not measure it BOTH ways?  Extended and compressed to see if there is a correlating change and what the difference is?  I note that Guzzi Steve mentioned above that it is measured with Fork Extended.

Ha ha, because that ship sailed. They're installed lol.

But I cannot see how the level could be the same extended as compressed.

[Bulldog9]

Ha ha, because that ship sailed. They're installed lol.

But I cannot see how the level could be the same extended as compressed.

I wouldn't expect it to be, but it would have been interesting to see what the difference is. I'll let you know this spring when I tackle the Stornello.

It's interesting that no one has weighed in on this.

[Bulldog9]

OK,

Just spent the morning looking through the V7ii ABS Service Manual.  Dang it........... I owe Kev another Beer.............. From the SUSP 171 page.


Filling oil
· Place the sleeve upright in a vice fitted with protection jaws.
· COMPRESS the sleeve in the stanchion.
· Pour part of the fork oil into the sleeve.
· Wait some minutes until the oil fills all the ducts.
· Pour the remaining oil.
· Pump a few times.
· Measure the air gap between the oil level and the rim.

THE SLEEVE MUST BE PERFECTLY UPRIGHT IN ORDER TO MEASURE THE CORRECT OIL LEVEL. THE OIL LEVEL MUST BE THE SAME IN BOTH STANCHIONS.

Characteristic
Oil level (from sleeve rim, without the spring and with stem at end of stroke) 120 +/- 1.5 mm (4.72 +/- 0.06 in)

[Kev m]

Will report back in a few weeks when I get it back on the road and test this fork fluid type/viscosity/level

Liqui-Moly 10W fork fluid / Kafia forks / 130 mm air gap (no spring/fork compressed)

Kev

Ok, winter got nasty and I didn't get back into the shop to finish putting the V7 fully back together until last week. And it wasn't nice enough to test until today.

As a recap, I overfilled using 400cc/tube and drew back down to this level by taking out of excess, I bet filling with about 375cc would have been about right.

I took her out for 100+ miles today on some of my favorite roads.

Unless by some miracle those roads repaired themselves over winter  the thicker fork oil and slightly larger air gap than spec worked wonderfully for me!

There is no doubt in my mind that I've gained some stability and damping from this change.

[faffi]

Oil viscosity determine damping, in both directions, while air gap affect springing. Some prefer more damping because it slows down the action at the front at the expense of grip. To a point - too little damping will also negatively affect grip, but in general a little soft damping will give more grip but also more movement and more rapid dive under braking, which is not to everyone's liking.

If the fork spring is correct for the load you carry, meaning you plus any passenger and luggage, air cap can be adjusted to prevent bottoming under maximum braking, since a smaller air gap will make the fork spring act more progressively. If your fork is far from bottoming when braking as hard as the front tire will allow, you can reduce oil level to soften the ride a bit, but more likely you are looking for softer springs.

[Kev m]

Oil viscosity determine damping, in both directions, while air gap affect springing. Some prefer more damping because it slows down the action at the front at the expense of grip. To a point - too little damping will also negatively affect grip, but in general a little soft damping will give more grip but also more movement and more rapid dive under braking, which is not to everyone's liking.

If the fork spring is correct for the load you carry, meaning you plus any passenger and luggage, air cap can be adjusted to prevent bottoming under maximum braking, since a smaller air gap will make the fork spring act more progressively. If your fork is far from bottoming when braking as hard as the front tire will allow, you can reduce oil level to soften the ride a bit, but more likely you are looking for softer springs.

So here's the thing. If I'm understanding you correctly in theory the two small changes seem to have made might work against each other slightly.

I will say that my impressions of the stock front suspension were that it was a little too soft, dampened slower and bottomed out too easily.

What appears to have happened from my test ride is it doesn't dive or bottom out as much and dampens more (doesn't pogo as much under some of the usual and unavoidable bumps in my favorite routes).

The slight change in viscosity would explain the pogo-ing.

The air gap would in theory have done the opposite of what it seems to have done.

However I'm still doubting the air gap spec as published from the factory vs what was done to my bike prior to delivery.
 
I'm leaving behind this record of what I did, how I did it, and the results for anyone else who faces the same conundrum.

Upon draining, I carefully measured the oil removed from both forks. I compared that to the spec Todd published on GTM early on with another 2013 w/ Kafia forks. It was very nearly identical.

I then filled with about that amount and air gap was way too big according to spec (160mm vs 120mm)

So I added more and drew it down to an air gap that, though 10mm larger than supposed SPEC was in theory 40mm smaller than what actually filling with the same amount achieved.

I settled on that level as a compromise between what I drained and what the factory seemed to suggest. I figured I could always remember the caps and add a bit more if needed though I hoped that would not be necessary.

100+ miles yesterday tells me that it is not.

Ymmv but I hope this helps someone else.

[Bulldog9]

I'll be doing the forks in the Stornello this spring/summer. I'm toying with putting a fork kit in it to match the nice BiTubo shocks I mounted on the rear, but MTF.

Fork oil does a couple things. It affects compression and rebound damping, keeps the fork lubed, and its level effects the spring rate. My XS11 and the Convert have 'air bladders' (lack of a better term) in the fork that you can raise or lower front spring rate by adding air pressure. More pressure, higher spring rate. Neither have any setting for compression and rebound settings, so oil viscosity has significant impact on compression and rebound.

The stock V7 forks have no adjustment for spring rate (air or otherwise) or compression and rebound, so oil viscosity and level are critical. As air compresses more than liquid a larger air gap will have a lower effective spring rate, a smaller air gap will have a higher effective spring rate. A heavier fork oil will slow damping in both directions, a lighter weight fork oil will have lower damping thus faster suspension response. It's a balancing act and is good and bad.

Before I changed the Fork springs in the Stornello, I bottomed the front forks all the time. NOT from braking, but from large bumps. The stock V7ii suspension front and rear is horrible, at least for someone 200lbs and rough roads. I imagine it is fine for some skinny jean wearing 150lb latte sipping hipster...... 

Once I added heavier fork springs (KTECH 7.5lbs), the front suspension has been very good if a little tall. Certainly not sport bike level, but for its purpose and with the Shinko 705's, it left nothing to desire. The Front Fork and Hagon rears were perfectly matched. I do find the damping a little light and need to do a fork oil service so will mirror what Kev did when I change the oil.

These new Bitubos have spring, compression and rebound settings so I will be able to match it to the front. Unless of course I stumble on an extra $800 and buy a Matris or Bitubo kit for the front forks......

I've found that porpoising is a result of mismatched damping, but mostly rebound damping. Spring rates matter too. This is true for cars and automobiles. I chased a porpoising issue on my 912 for a year until I changed out the rear shocks to firmer. So Kev, the firmer front fork with higher viscosity and firmer damping probably brought it in line with the rear. KUDOS!

If the front or rear are slower to rebound, be it from a mismatched spring rate or damping, the bike will pitch back and forth. Can happen with compression too, but I think it is more noticeable on rebound. I like a medium to high compression and medium to low rebound. The faster the wheel rebounds the higher your traction level, but ZERO rebound is not good either, it makes the ride very busy. It's a fine balance. 

[Kev m]

Yeah I probably have got it balanced better finally with how I've set up the YSS shocks on the rear.

And yes effectively I seen to have reduced the air gap from actual (not from theoretical "spec"), which better matches the soft OEM spring to my less than diminutive size (currently ~240 but shrinking).