Fork Sag

[grubsie]

Last fall I was riding a 2002 RSV midnight with 47K on the clock when a deal for a 2008 RSV Standard with only 4,700 miles on it came along on a deal from the one owner bike that I just couldn't pass up.

 

During the winter, I stripped all the goodies from the 02 and put them on the 08. Everything but the rear lowering kit which I have that put aside in case I decide to put it on the 08 this winter.

 

While checking out the differences between a Midnight and Standard, I noticed that the fork tube covers on the Midnight were chrome and the Standard were stainless. But then I noticed something else with the bikes sitting on their side stands. The distance between the lower fork tube covers the fender mounts of the fork lowers seemed shorter on the 08 vs the 02 so I measured the distance. The 08 was 5" and the 02 was 3 3/4". Both bikes had 0lbs air pressure in them. Sat on both and noticed the 08 front end dropped considerably more than the 02. Applied the front brake and rocked both bikes and the 08 appeared much softer than the 02. The front end on the 08 also dipped much easier on the road than the 02 when I applied the brakes

 

I haven't checked the fork oil on the 08 yet, so maybe that is the culprit. Can't imagine that the oil could affect the sag like that when the bike is just sitting there. I just resorted to running 7lbs of air for this past riding season but it is on my todo list for this winter. Is there any other reason why they would be sagging besides the oil? This bike was untouched mechanically, so I know that no one has messed with anything previously.

 

That being said and since I am going to be tearing into the forks anyway, I read a couple of old threads on here about guys using Sonic springs with reviews about them giving a better ride. The details are limited though as nobody did any kind of detailed write up on them. They look like a low cost and effective improvement so maybe the way to go? I went to Sonic's website and there isn't a contact number posted so I used their online "Contact Us" form so hopefully I will hear back.

 

The older threads:

http://www.venturerider.org/forum/showthread.php?56603-Any-threads-about-resealing-the-front-forks-and-replacing-the-springs&highlight=sonic+springs

 

http://www.venturerider.org/forum/showthread.php?55285-Beefier-springs-fork-oil-change-and-steering-head-lubed!

[cowpuc]

In it's purest form, the sag height on a scoot is spring dependent. The oil in the system is used for dampening purposes = the oil is forced thru shim stacks or other forms of orvices that dampen by restricting the oil flow and therefore slowing down the bouncing up and down that would occur if you were running just springs.

IMHO, all things being equal = meaning the forks on both scoots are set at the same height in the triple trees, the bike that sits the highest (least amount of sag) with no air in them probably has a set of aftermarket springs in it and the one with the most sag has stock springs in it..

I have no experience with the 2nd Gens so I am sort of going out on a limb here in my reply but I can tell you this - from the factory Mom Yam used what I call "ink pen springs" in the front forks of the 1st Gens.. I say this cause if a person opened up the forks on a 1st Gen and removed the fork springs and laid them next to a set of,, sayy,, Progressives - that person would INSTANTLY see the difference. Quite frankly,, I always theorized that Mom Yam probably had stock in Bic Ink Pen Inc. and had access to their over stock of springs = it's that obvious.. It would not surprise me to find similar ink pen springs in the Gen 2 like you are having fun with.

Bottom line, if it were mine I would pull the springs and replace with a good set of aftermarkets (thinking "Sonic" springs may just be another brand of progressively wound springs? Not sure,, maybe someone who really knows what they are talking about will chime in and set us both straight ). Drain and refill the forks to spec with a good 12.5 weight fork oil. On my 1st Gens one of the things I never had to fool with again after doing what I am talking about here is running air in my forks. In my case (and this may be due to some extreme pounding I have put my forks thru) I noticed that my fork seals seemed to last longer if I refrained from using air over the hydraulics in my forks (no longer put any air in my forks). I also right away when ever I switch from stock springs to Progressives that my Ventures come out with a whole new handling charm - THEY LOVE TWISTIES and dont bottom out on rough roads even when two up!!

[Du-Rron]

Drain and refill the forks to spec with a good 12.5 weight fork oil.

 

Hi jacking here...

 

Would you use fork oil, 5w-20 motor oil, or Automatic Transmission Fluid nowadays?

[M61A1MECH]

While checking out the differences between a Midnight and Standard, I noticed that the fork tube covers on the Midnight were chrome and the Standard were stainless. But then I noticed something else with the bikes sitting on their side stands. The distance between the lower fork tube covers the fender mounts of the fork lowers seemed shorter on the 08 vs the 02 so I measured the distance. The 08 was 5" and the 02 was 3 3/4". Both bikes had 0lbs air pressure in them. Sat on both and noticed the 08 front end dropped considerably more than the 02. Applied the front brake and rocked both bikes and the 08 appeared much softer than the 02. The front end on the 08 also dipped much easier on the road than the 02 when I applied the brakes

 

Just for grins, if you have the means, jack the bikes up and measure the distance between the tube covers and the fender mounts with no weight on the forks.

Also curious, did you check to see if the tins are the same length, maybe one type is longer than the other?

[grubsie]

Bottom line, if it were mine I would pull the springs and replace with a good set of aftermarkets (thinking "Sonic" springs may just be another brand of progressively wound springs?

 

I am with you on this cowpuc. Unfortunately, in all my searching on the web, there are all kinds of progressive springs for 1st Gen Ventures and 2nd Gen RSTD's, but nothing for 2nd Gen RSV's unless the springs in the RSTD's and RSV's are the same. My research shows different part numbers for OEM springs.

 

Just for grins, if you have the means, jack the bikes up and measure the distance between the tube covers and the fender mounts with no weight on the forks.

Also curious, did you check to see if the tins are the same length, maybe one type is longer than the other?

 

I sold the '06 this past spring M61A1MECH , I did all the things you mentioned. The tins were the exact same size. the distance between the tins and the fender mounts were the exact same length when on the jacks. I had them on jacks side by side when I took the measurements.

[cowpuc]

Hi jacking here...

 

Would you use fork oil, 5w-20 motor oil, or Automatic Transmission Fluid nowadays?

 

Sup Duey!! Because it's much against my upstanding club etiquette allow me to apologize too for participating in another ..

Back in my early days of MX'n after Yamaha invented the Mono shock and our MX scoots got some very serious suspention, the whoops got deeper and the jumps got farther apart.. During that time period it was not uncommon to swap out fork fluid between heats to refresh the suspention. I discovered by hap err chance (always playing with the scoot) that ATF was actually a very very good alternative to Belray Fork Oil and about 1/4 the price. It got to be a fairly common practice around the tracks.. By the mid 80's Honda was actually specing ATF for some fork applications in the dirt world and their engineers declared ATF as a 10wt Fork Oil..

Something to remember about dirt bike suspention (and other track bikes, like modern day MotoGP sport bikes = R1's-Gixxers and the like, as well as some uppity street bikes) is that the forks are usually equipped with "clickers" that adjust the shims/orvices that restrict the oil flow thru them that create dampening.

On my Gen 1's (and quite possibly on the Gen 2's too) there are no clickers and long ago I played with "dialing in" the forks on my Venture after replacing the OEM springs with Progressives.. Having no clickers to dial them in with and not seeing the advantage to tearing my forks apart to try a reshim/reorvice in forks dampner rods so I could change the fork oils every weekend like I use to do on my MX scoots - I decided to play the Fork Oil weight game and increase/decrease the dampening effect thru oil viscosity (this is another very common practice and why there are multiple Fork Oil viscosities in tiny increments)..

Thru testing, for my ride style, I found 12.5 weight to be perfect when utilized with Progressives and no air added. I have also found that in a pinch, 20 weight Fork Oil used when incorporated with partially sacked out stock Ink Pen springs can slow down the damping enough to keep the forks from bottoming out harshly giving me a chance to get some Progressives installed and keep from ruining the dampeners and having to get into a fork job..

As far as using 5w-20 motor oil? ,,, never tried it.. I personally dont see where using a multi-grade oil would be advantageous when used in a hydraulic fluid application.. If I found myself in the need of Fork Oil and in a bind - I think I would look for a straight viscosity motor oil to use instead but - on the same token,,, I would definitely try the 5w-20 before running em dry!!!!!!

 

Bottom line - in our day and age, Fork Oil is plentiful and highly purposefully engineered.. I would definitely advise to use nothing by Fork Oil for Fork applications.. I know,, I could have said that right at the beginning instead of writing that thesis like I did but I figured I may as well make this a good one as long as you and I are risking getting put on probation anyway

The End

[cowpuc]

I am with you on this cowpuc. Unfortunately, in all my searching on the web, there are all kinds of progressive springs for 1st Gen Ventures and 2nd Gen RSTD's, but nothing for 2nd Gen RSV's unless the springs in the RSTD's and RSV's are the same. My research shows different part numbers for OEM springs.

 

Grubs,, a quick shop on Ebay revealed this selection of Progressives for the RSV: https://www.ebay.com/sch/i.html?_odkw=sonic+springs+YAMAHA+VENTURE&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xfork+springs+Royal+Star+Venture.TRS0&_nkw=fork+springs+Royal+Star+Venture&_sacat=0

 

Also,, here is a thread that you might find interesting.. Lots of RSV Guru chatter happening in here IMHO: http://www.venturerider.org/forum/showthread.php?19608-Front-Fork-Sag/page2&highlight=sonic+springs

[cowpuc]

Here is another interesting point... These springs are OEM stock "ink pen springs" that are being sold as used parts = notice in particular how they are wound = look just like an ink pen spring IMHO:

https://www.ebay.com/itm/Yamaha-Royal-Star-Venture-XVZ-1300-Fork-Internal-Spring/381883488429?hash=item58ea0798ad:g:IpUAAOSw-0xYQMnv&vxp=mtr

 

and now a quick peek at a progressively wound fork spring.. Notice the difference?? That tighter winding at the end of the spring makes for a much more progressive and gradual increase in stiffness as the spring compresses and makes it very difficult for the spring to abruptly come to stop at full compression.. Word of note,, I am not sure this is correct but I have always installed those gradual increasing windings to the bottom of the fork when installing. Also, with the 1st Gen's = the OEM ink pen springs are much smaller diameter on the wire of the spring.. Definitely worth swapping out IMHO. Here is the comparison pic:

https://www.ebay.com/itm/11-1144-FRONT-FORK-SPRING-YAMAHA-XVZ-1300-TF-Royal-Star-Venture-1999/322544642189?hash=item4b1928a88d:g:uCEAAOSwZ4dZNnvE&vxp=mtr

[grubsie]

Grubs,, a quick shop on Ebay revealed this selection of Progressives for the RSV: https://www.ebay.com/sch/i.html?_odkw=sonic+springs+YAMAHA+VENTURE&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xfork+springs+Royal+Star+Venture.TRS0&_nkw=fork+springs+Royal+Star+Venture&_sacat=0

 

Also,, here is a thread that you might find interesting.. Lots of RSV Guru chatter happening in here IMHO: http://www.venturerider.org/forum/showthread.php?19608-Front-Fork-Sag/page2&highlight=sonic+springs

 

Thanks cowpuc.

Never even thought of ebay. I went to a lot of sites that had them for all kinds of Yamaha's except for the RSV.

 

I knew I would find someone here smarter than me. Don't think I'm flattering you cowpuc, 'cause I'm not very smart to begin with.

[BlueSky]

My 85 Kawasaki ZN700 Shop Manual specs SAE 10W20 oil in the forks? I actually put 5W30 in it the second time I replaced the fork seals and the forks are rather stiff. I plan to change it to 10W fork oil. Modern engine oils have the additives now that make them super slick and that may be why my second set of fork seals starting leaking recently?

[Mike G in SC]

I just ordered/received a Progressive Suspension spring set for my "new" 2006 RSTD per my tech. But for a different reason.

Amazon $87. https://www.amazon.com/gp/product/B000GTXIM2/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

 

On my old 2006 RSTD (110K miles), years back a friend lowered the front, similar to you do on the RSV, but only 1/2" to 3/4" as that is about all you can do before the Schrader valves hit the handle bars.

I also lowered the rear with the Barons kit but fabricated links that only drops the rear 3/4". So it was leveled, perfect for me with 29" inseam.

 

I got the new RSTD and moved "my stuff" over, including the rear lowering kit. (Gave the old bike to my son-in-law yesterday,, happy boy.)

I asked my tech to drop the front like the old bike and he suggested that instead of just dropping the triple tree on the forks as before, to get the Progressive Springs and he can cut the spacer to lower the front internally instead.

It will still be a tear down of the front forks, about the same labor, but will have much better results because of the new springs.

 

For those who know the use of the Progressive Suspension kit,,,, does this idea for lowering the front pan out?

 

Thanks, Mike G in SC

[cowpuc]

Here's my take on lowering with spring height instead of raising the forks in the trees Mike. The problem with cutting down the preload on the springs (cutting the spacers) to reduce overall height of the scoot is that you are essentially reducing the amount of travel that you have in your front suspention. I suppose that the arquement could be made that raising the tubes in the trees actually changes the steering geometry but,, I have a hunch that reducing the travel by allowing the tubes to travel into the fork legs (increasing sag) will have the same effect because the forks move at a rear ward angle when they compress too.. I think if it were mine and knowing the type of riding I do (pack heavy, get a little off roading in once in a while so I need all the travel I can get) I would be inclined to move the forks up in the tree's even if I had to get short set of bar risers to make the job doable..

Another thought,,, I have found that on my 1st Gens that I ALWAYS swap in Progressives on that when I do go with the Progressives I NEVER run air in my forks.. If I am understanding you here (thinking your shrader's on are the fork caps?) = I think I would consider removing the shraders and capping the holes and see if the fork caps would then fit.. Wonder if the flat caps off a 1st Gen would fit your scoot and give you the added clearance you need??

I know,, ol Puc is all ,,, all comin from a good heart though

[Mike G in SC]

Here's my take on lowering with spring height instead of raising the forks in the trees Mike. The problem with cutting down the preload on the springs (cutting the spacers) to reduce overall height of the scoot is that you are essentially reducing the amount of travel that you have in your front suspention. I suppose that the arquement could be made that raising the tubes in the trees actually changes the steering geometry but,, I have a hunch that reducing the travel by allowing the tubes to travel into the fork legs (increasing sag) will have the same effect because the forks move at a rear ward angle when they compress too.. I think if it were mine and knowing the type of riding I do (pack heavy, get a little off roading in once in a while so I need all the travel I can get) I would be inclined to move the forks up in the tree's even if I had to get short set of bar risers to make the job doable..

Another thought,,, I have found that on my 1st Gens that I ALWAYS swap in Progressives on that when I do go with the Progressives I NEVER run air in my forks.. If I am understanding you here (thinking your shrader's on are the fork caps?) = I think I would consider removing the shraders and capping the holes and see if the fork caps would then fit.. Wonder if the flat caps off a 1st Gen would fit your scoot and give you the added clearance you need??

I know,, ol Puc is all ,,, all comin from a good heart though

 

Puc, thanks for the input. I will talk to my guy. (He is actually a lead tech at a dealer.) This bike is now just my solo bike (We got a GW trike for two up and trailering). Mike G in SC

[ragtop69gs]

My '01 was sagging and diving upon brake application, it also always wanted to track to the outside of any sharp curve. The following cured all of this.

 

Another option is Sonic Springs. They are a straight rate spring, I installed the 1.2 rate springs, along with going to 15W fork oil, new bushings and seals. Made for a much better handling bike.