[Brother Number One]

Changed mine the other day http://sawthingsclearer.com/2015/10/31/fork-oil-changed/

and noticed the oil colour was different in each leg (like the OP).  I used ATF with a 146mm (roughly) gap and I'd say the results are on the soft side.  I may be tempted to try motor oil, I like this guy's discussion http://www.deleveld.dds.nl/forkoil.htm (although he doesn't seem to know the difference between quick-steering and over-steering).

[Bixxer Bob]

Out of curiosity,what's your view on using engine oil? Some do?

The Haynes manual for my 1972 350 Yam says use 20.50 engine oil, but that was a long time ago.

[Sin_Tiger]

The Haynes manual for my 1972 350 Yam says use 20.50 engine oil, but that was a long time ago.

Multigrade? That's really going to give your viscosity phobia a workout 

[Mustang]

I bought  my 73 RD350 brand new and the first time I changed the fork oil it smelled like rancid fish oil  .
 

[KuzzinKenny]

  I want to see where this goes as i should be changin me fork oil over the winter.

also lookin for any comments about ........

race tech  Gold Valve Cartridge Emulators or other makes 

front springs and oil types 

and don't go quotin stuff in the £1000s 

cheerz

KK

ps anyone tried these.....

http://www.squaredeals-ltd.co.uk/yss-pd-triumph-fork-valves--fork-cartridge-emulators-43mm-diameter-forks-30318-p.asp

[threepot]

I bought  my 73 RD350 brand new and the first time I changed the fork oil it smelled like rancid fish oil  .
 

Back then,it probably was

[Sin_Tiger]

I bought  my 73 RD350 brand new and the first time I changed the fork oil it smelled like rancid fish oil  .
 

That would explain why it cornered like a dead flounder 

If I understand the workings of these "Emulator" & YSS valves, you are in fact replacing the effect of the stock valving by drilling them out and fitting a (hopefully) better quality adjustable valve body? YSS don't appear to list one for the Girly although they do for the Steamer and other 885's. I did fit the Ricor Intiminator valves to the Thruxton, they are a little different in that they don't take over the damping of the stock valving but try to limit dive by restitricting flow when braking using what appears to be basically a jiggle valve. They do work but you are still working with the stock damping which now has to cope with a restricted flow, hence they recommend changing to 5W oil. The advantage is that you don't have to terminally alter your stock fork internals, so you can whip them out if you don't like them.

For a more technical assesment I think we need to ask Sasquatch, he probably has had first hand experience.

I've never used synthetic fork oil, has anybody else? I would expect it to have a longer effective life span and be less prone to frothing but that doesn't really make a difference unless you're racing or giving it big licks on a forestry road - don't look at me 

[Sasquatch]

A lot to address here.

Motor oil in forks:  Why not.  The only draw back would to get your oil weight correct.  But in theory, it should work fine.  I am a huge fan of ATF.  It works great in damping tube forks like on the pre-1050 Tigers.  I use ATF in my own forks with RT Emulators.

Add on valving to damping tube forks:  I have used and tested both the Race Tech Emulators and Intimidators by Ricor.  I tested them back to back in my own Tiger.  I have to give RT the nod in having the better setup.  The RT emulators are also adjustable, although you have to remove them to adjust them.  I felt that the Ricor's were too harsh.

Springs:  You basically have two types available.  Straight rate and rising rate, commonly called progressive.  Some bikes work really well with a rising rate spring, and some customers really like them.  I am not one of them.  That said, I do have them on the back of my Tiger as the suspension is of a no linkage type.  Getting some more progression in the spring helped the ride.  But I do not like them in forks as a general rule. 

By design, springs are rising rate all on their own.  Say you have a 1.0kg/mm set of fork springs.  It takes 1kg to squish them 1mm.  It takes 2kg, to move them another mm, 3kg to move them another mm, and so on and so forth.  On a rising rate spring the amount of additional weight to move the next increment of distance is greater than the last one, so the compression curve goes up much steeper.  I simply do not like the feel of them.  Mushy then harsh.

[KuzzinKenny]

Cheerz Sasquatch  that info has help me greatly but has made a new ?? 

on the Mobil oil site they show 6 types O' ATF   

do you know what rate the standard cast wheel front spring are ??

as i might just fit the R/T emulators !!

KK

[Sasquatch]

I use Dextron III ATF.

[Bixxer Bob]

Looks like it's way cheaper than fork oil 

[JayDub]

Typical!! I just bought 2lt of Motul semi-synth 

[KuzzinKenny]

After a bit O' researchin i only came up these.....

Racetech gold valve emulators FEGV S4301

and

YSS 360

anyone have any preference 

the YSS is cheaper 

KK

ps does this still work.....

http://www.adventurepowersports.us/home.html

  

[Sasquatch]

Race Tech is the original designer.  I assume YSS just copied RT's design.  I am a YSS dealer and have used their shocks on some applications with good results but I have never tried or used their emulator valves.

[Sin_Tiger]

YSS 360

anyone have any preference 

Guinea pig