Evo fork oil - Page 3

crawsue · 21-10-2024, 03:46 PM

Been rereading some threads including this one re the Evo Marzocchi forks , although I had mine “K-teched “ a couple of years ago I still feel that they are too firm, the invoice for the work is showing that they used “HPSF -017 “ in the rebuild. I notice in this thread that someone is running SAE 5 …..Unfortunately our technical sage Vince has stopped contributing at the moment, has anyone any experience in this field ? Regards Crawsue.

Dukedesmo · 21-10-2024, 04:59 PM

My Monster forks are 916 Showa units which I took to Ktech for valve kit & re-spring as the springs from the 916 were too firm due to the Monster being a lighter bike.

Ktech used 5w oil in them (they also used 5w in my 916 Ohlins) when they did the job, IIRC they said because it makes them smoother/more progressive?

They work nicely but I found that they would bottom out under extreme braking. I asked Ktech and they advised to add an extra 5 or 10ml of oil to each leg. I did and this solved the bottoming out.

So I guess the oil and the quantity can be used to alter the way the forks work however, if they're just too firm then maybe you need lighter springs?

crawsue · 23-10-2024, 02:28 PM

Unfortunately K-tech only supply springs down to 8.5…which should be spot on for my dressed weight…..can anyone confirm that the HPSF -017 specification is in fact SAE 17 ? It seems an arbitrary spec/ number….?

Mr Gazza · 23-10-2024, 04:26 PM

I just googled HPSF -017 and that specific oil didn't come up but it does seem that the number after HPSF (high performance suspension fluid.) doesn't bear any relationship with the viscosity. So I doubt it is 17w.
I did note that they go down as low as 2.5w and maybe lower, so you shouldn't have any trouble finding a lighter oil.
Best people to ask is going to be K-Tech.

Regarding the "firmness" of your forks. Have you tried adjusting the damping? if indeed you have adjustable damping?

Darren at MCT actually put thicker than standard oil in mine (15W I think) And that certainly made the adjustments more vivid than previously.
I backed off the compression a couple of clicks to make it more comfortable over the Norfolk B-roads and likewise the rebound.
That made it worse and so I called Darren and he said always do more to the rebound than compression. So I backed off the rebound a couple more clicks and that did the trick, it's been fine ever since.
Just wondered if it just needs a little play? Note your current setting before you adjust though.

Edit.. Just found this. https://www.propowermx.co.uk/product...EaApHCEALw_wcB
Looks like you already have 5w?

crawsue · 24-10-2024, 11:16 AM

Thanks for doing that research Garry,I’ve phoned K-tech this morning and they’ve suggested some rebound adjustments to try….and if it’s still too firm remove some oil. They confirmed that the 8.5 nm springs should be correct for my all-up weight. Annoyingly the factory set up on my compression only Trumpet 1050 st forks gives a much superior ride …..maybe I’m just too demanding….��

21-10-2024, 03:46 PM	#31
crawsue Bronze Member Join Date: Nov 2016 Location: Glasgow Bike: M1100evo Posts: 276	Evo fork oil. Been rereading some threads including this one re the Evo Marzocchi forks , although I had mine “K-teched “ a couple of years ago I still feel that they are too firm, the invoice for the work is showing that they used “HPSF -017 “ in the rebuild. I notice in this thread that someone is running SAE 5 …..Unfortunately our technical sage Vince has stopped contributing at the moment, has anyone any experience in this field ? Regards Crawsue.

21-10-2024, 04:59 PM	#32
Dukedesmo Registered User Join Date: Sep 2010 Location: Leics Bike: M900 Posts: 2,894	My Monster forks are 916 Showa units which I took to Ktech for valve kit & re-spring as the springs from the 916 were too firm due to the Monster being a lighter bike. Ktech used 5w oil in them (they also used 5w in my 916 Ohlins) when they did the job, IIRC they said because it makes them smoother/more progressive? They work nicely but I found that they would bottom out under extreme braking. I asked Ktech and they advised to add an extra 5 or 10ml of oil to each leg. I did and this solved the bottoming out. So I guess the oil and the quantity can be used to alter the way the forks work however, if they're just too firm then maybe you need lighter springs? __________________ M900, 916, LeMans II.

23-10-2024, 04:26 PM	#34
Mr Gazza Lord of the Rings Join Date: May 2013 Location: Norwich Bike: M900sie Posts: 5,961	I just googled HPSF -017 and that specific oil didn't come up but it does seem that the number after HPSF (high performance suspension fluid.) doesn't bear any relationship with the viscosity. So I doubt it is 17w. I did note that they go down as low as 2.5w and maybe lower, so you shouldn't have any trouble finding a lighter oil. Best people to ask is going to be K-Tech. Regarding the "firmness" of your forks. Have you tried adjusting the damping? if indeed you have adjustable damping? Darren at MCT actually put thicker than standard oil in mine (15W I think) And that certainly made the adjustments more vivid than previously. I backed off the compression a couple of clicks to make it more comfortable over the Norfolk B-roads and likewise the rebound. That made it worse and so I called Darren and he said always do more to the rebound than compression. So I backed off the rebound a couple more clicks and that did the trick, it's been fine ever since. Just wondered if it just needs a little play? Note your current setting before you adjust though. Edit.. Just found this. https://www.propowermx.co.uk/product...EaApHCEALw_wcB Looks like you already have 5w? __________________ Last edited by Mr Gazza; 23-10-2024 at 04:34 PM..

23-10-2024, 02:28 PM	#33
crawsue Bronze Member Join Date: Nov 2016 Location: Glasgow Bike: M1100evo Posts: 276	Unfortunately K-tech only supply springs down to 8.5…which should be spot on for my dressed weight…..can anyone confirm that the HPSF -017 specification is in fact SAE 17 ? It seems an arbitrary spec/ number….?

24-10-2024, 11:16 AM	#35
crawsue Bronze Member Join Date: Nov 2016 Location: Glasgow Bike: M1100evo Posts: 276	Thanks for doing that research Garry,I’ve phoned K-tech this morning and they’ve suggested some rebound adjustments to try….and if it’s still too firm remove some oil. They confirmed that the 8.5 nm springs should be correct for my all-up weight. Annoyingly the factory set up on my compression only Trumpet 1050 st forks gives a much superior ride …..maybe I’m just too demanding….��