Race Tech Gold Valve Cartridge Emulator Install (FEGV-S4301)

Well, as many might know, Race Tech (www.racetech.com) does NOT make anything specifically to fit Guzzi Stone/Jackal/Special Sport with 45m Marzocchi forks.  They DO however make them to fit 43mm Showa forks.  In the general instructions for these (http://www.racetech.com/articles/EmulatorFitting.htm) they say the emulator can be up to 4mm smaller in diameter than the inside diameter of the fork tube.  Well, the 45mm Guzzi tubes measure 39.5 mm inside.  The Race Tech FEGV-S4301's are 36mm outside diameter.  Simple math tells you 39.5-36=3.5!!!  Well, in my book, that is less than the 4mm in the instructions.  So, having found a set that will fit (buy them at www.parts411.com as they are cheaper there than directly thru Race Tech), now all we need to do is adapt them to the stock damper tube.  The top of the Marzocchi damper tube is NOT flat.  The tube is actually a metal tube with a white plastic 'piston' swaged on top. This means there is a circular 'hump' on top of the damper tube (sort of like figure 2 in the above linked Race Tech document).  To overcome this I designed an adapter (
See picture here).  You will need TWO of these made out of aluminum - one for each fork. The bottom of the adapter (smaller inside diameter) centers up on the damper tube and the top (larger inside diameter) accepts the Gold Valve Emulator.
An important note at this point - once you have the emulator set in the adapter, measure the height of the assembly - you will need to remove the amount you measure from the spring preload tube.  I THINK the number was around 38mm or so that I removed from the preload spacer.  I will have to check that for sure. Here are the simple steps and my initial settings.
I ASSUME you are familiar with dismantling a damper tube fork before proceeding. Also, as a note, the stock fork springs on my stone measured around .85 to .90 kg/mm


1. Remove front brake calipers

2. Remove front wheel. LEAVE front fender/fork brace on for now.

3. Using a long 8mm allen socket (or 8mm allen wrench with the leg cut off and a socket), reach thru the bottom of the fork legs and crack loose the damper tube bolts.  Do NOT remove them yet.

4. Now remove the front fender/fork brace

5. It helps to loosen the fork tube caps before removing the legs.  You will need a 30mm socket for this. To reach the cap better, you can slide the tubes down to the lower triple tree and retighten the lower triple tree bolts to clamp the tube, then remove loosen the fork tube cap.

6. Remove the fork legs from the bike

7. Remove the fork tube caps, turn the legs upside down to drain the oil. Note, the main spring and preload spacer will come out when you turn everything upside own.  Pump the fork tubes to make sure all/most of the oil comes out.

8. Collapse the forks entirely.  Now, remove the damper tube bolt in

9. Let damper tube slide out of the top of the forks.  Drill holes in the damper tube per the Race Tech instructions.  You will need to enlarge the original holes.  Drill one set above the original holes and one set below. Me being a lucky bastard have a Bridgeport mill, so I chucked mine up in a swedish head and plunged them with an endmill.  If all you have is a hand drill, take your time.

10.  After having drilled and de-burred the holes and removed all metal bits, re-install the tubes.  Use NEW washers on the damper tube bolts (MG part number 03 53 05 29).  Tighten the damper tube bolts as best you can at this point. Now it is safe to extend the forks.

11. Measure the height of the valve emulator mounted on the adapter and remove this much from the stock preload spacers.

12. Drop in your adapter making sure it seats on the damper tube.  Set you r Gold Valve Emulator per the Race Tech instructions.  I used the standard 2 turns.  Drop it in the forks making sure it seats on the adapter.

13. SLOWLY add 200cc fork oil.  I used 15wt.  Insert the spring and preload tube so you can hold the adapter and emulator in place and SLOWLY pump the fork.  Add another 300cc of oil and SLOWLY pump the forks.  Collapse the forks all the way and remove the spring and spacer.  Add fork oil until the level is 6 inches from the top of the tube.

14. Install the spring, cut down preload spacer and fork tube cap.

15. Install the fork legs.

16. Install the front fender/fork brace.

17. Snug up the damper tube bolts in the bottom of the forks.

18. Install front wheel and brake calipers.

19.  Go for a ride!!  I used the standard 2 turns and 15 wt. oil measured 6 inches from the top of collapsed forks with no springs/spacers as a starting point.  As I ride more, this may change.  The weight of the fork oil can be varied to change rebound damping the turns on the gold valve are used to change the compression damping.  After a short quick ride, I noticed a much better fork action.  It's much smoother than the stock set-up. Enjoy.

Jeffery H. Brannen