Marzocchi Forks

[docc]

Well done, guys! Just to restate and share what I learned here about tuning with fork oils, not all "5 wt" or "10 wt" fork oil is the same. Thinner oils do seem to flow better through the Marzocchi's tight damping.

 

See Peter Verdone's great work on listing many common oils using centiStokes@100ºC (a much more accurate unit than "# weight" ):

 

http://www.peterverdone.com/archive/lowspeed.htm

 

(I have had good results with BelRay HV1 5W that I understand comes in at 19.50 cST)

[Lucky Phil]

Well done, guys! Just to restate and share what I learned here about tuning with fork oils, not all "5 wt" or "10 wt" fork oil is the same. Thinner oils do seem to flow better through the Marzocchi's tight damping.

 

See Peter Verdone's great work on listing many common oils using centiStokes@100ºC (a much more accurate unit than "# weight" ):

 

http://www.peterverdone.com/archive/lowspeed.htm

 

(I have had good results with BelRay HV1 5W that I understand comes in at 19.50 cST)

Because not all brands of fork oil weights are the same viscosity for their advertised weight what I do when I pull down a set of forks is measure the viscosity of what comes out so I have a baseline for what goes in irrespective of brand. So I use a very rudimentary method of a syringe cylinder with the plunger removed and a stop watch. Fill the syringe with your finger over the outlet and then remove and time the emptying or a set volume and compare it to the new oil you are putting in.

Then mix and match weights to get what you want. If you need a different weight to whats in there at least you have a baseline and can estimate the change based on how it compares to the new oil.

Its annoying when you're happy with the damping the way it was and refill with the same weight only to find the damping has changed.

 

Ciao 

[Chuck]

Well done, guys! Just to restate and share what I learned here about tuning with fork oils, not all "5 wt" or "10 wt" fork oil is the same. Thinner oils do seem to flow better through the Marzocchi's tight damping.

 

See Peter Verdone's great work on listing many common oils using centiStokes@100ºC (a much more accurate unit than "# weight" ):

 

http://www.peterverdone.com/archive/lowspeed.htm

 

(I have had good results with BelRay HV1 5W that I understand comes in at 19.50 cST)

Thanks for the link, Docc.. I've never seen it. 

[knumbnutz]

Hi Everyone,

Small update, I assembled the forks last night and used 10wt Motul fork oil and there is a definite improvement but not what I expect for the compression cycle.

So I then I assembled the Rebound and used the same fork oil. Big change!

Now the rebound has compression and rebound.

MMM... I then assembled the entire front end and checked (as best as I could) how they felt combined.

I think it is much better and so I then compared it to the TRX (R1 2007 forks) and Ducati ST2 I have and it was somewhere in between the two, the ducati felt soft and the TRX quite firm.

 

Im now going to run with this and finish the bike. If it turns out poxy on the road then there is nothing more to try without getting different front end.

Im also confident that it will be ok though, there is now dampening both ways.      

[gelos]

Hi, It is very interesting report. Do you know what oil type you had before repair/rebuild? I thought that specification on 10W oil from the Guzzi workshop manual is not very regular. I feel the bike run especially at cold temperature as much overdamped. But I use Putoline HPX 10W fork oil, according to 40/100°C viskozity equals Motul 15W. I think its time to change my oil.

 

[knumbnutz]

15wt would make sense !

It was far too light for 15wt oil though, I reckon the spec for the fork was 15wt and the factory fitted "15wt" which was more like 5wt hence the softness everyone feels