Engineered in Italy, it was ridden, tested and abused around the world. Function is like modern MX-suspension forks: Steel spring and open oil bath damping. Both spring and damper are more than big enough for heavy DH-use.
Technical Data:
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Releases:
Because of permant improvement of the fork, there are several versions. The actual version is Release 8.
Click if you want to see the photos of various versions:
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Service instructions
Please click for a diagram of the internals of the fork: 866 Detail (80KB)
Screw tighten torque:
Change oil:
Racers should change the oil of the fork AT LEAST two times per season! Donīt worry about that, oil is not expensive if you buy it in Motorbike-shops, and changinī oil in the 866 Dragster is easily done in minutes!
Normal racers should use fork suspension oil with SAE 4 or SAE 5. Heavy riders can try SAE 8 or ATF (Automatic transmission fluid).
1. Turn the fork upside down.
2. Open the two nuts at the bottom of the fork.
3. Unscrew both nuts from the damping cartridges.
4. Turn the fork in normal position. Caution! The oil flows out!
5. Put the old oil out of the fork. Pump the fork some times.
6. Take the new oil. Put in about 250ml of suspension fork dampening oil in the leg with the damper. Use 100ml ATF in the other leg.
7. Close the fork and youīre ready to go!
Change the spring rate:
The spring rate can be easily changed:
Either with the spring itself and other springs, distance tubes, etc..
or with the oil level.
1. Make the spring more linear: Put away any plastic distances and use small springs or elastomers.
2. Make the spring more progressive: The air in the fork is used as an aditional spring. Reducing the air causes a more progressive spring rate. If you want the fork to be more progressive, put a little bit more oil in the fork-leg with the damper. Try 300ml.. then 350.. and so on.
Change the settings of the damper:
The 866 Dragster is engineered for the racer. Any adjustment on the damper can be easily done in minutes. You need not to take apart the whole fork, only open the nut at the bottom of the fork.. put out the oil, open the oil bath cartridge and now you are ready to change anything you want!
1. Turn the fork upside down.
2. Open the two nuts at the bottom of the fork.
3. Unscrew both nuts from the damping cartridges.
4. Turn the fork in normal position. Caution! The oil flows out!
5. Put the old oil out of the fork. Pump the fork some times.
6. Open the top caps of the fork.
7. Take out the the spring and damping unit.
8. Loose the small nut under the top cap.
9. Unscrew both top cap and the small nut.
10. Take the spring and the spring guides away.
11. Push the damping-shaft through the damping cartidge until you see the piston.
Youīre ready to change the settings.
Now we will talk about some theory:
During compression the oil flows through the piston holes. The oil press the valve-shims back.
That means: More valve-shims directly after the piston make the fork harder for small bumps. A piston with smaller holes will make the for harder for big bumps. Lighter oil will do the same for small and big bumps.
Other tuning possibilities:
Piston : 1 valve-shim : distance-ring : 2 valve-shims : aluminium-shim
This will make the fork sensitive for small bumps, but when the shim moves back, the the other valve-shims will be pushed - harder for big bumps.
During compression the damping tube moves inside the open oil bath cartridge. The oil inside has now to move out, because the tube needs some volume.
If you look at the damping cartridge you will see a hole at the bottom. Depending on the size of this hole, the oil can flow faster or not.
Big hole means: No difference in small bumps, but less damping progression in big bumps.
Small hole: No difference in small bumps, but more damping progression with big bumps.
After compression the fork has to move out:
Now the oil has no possibility to flow through the piston, because the valve-shims are closing the piston. Now look at the damping-tube. You will seee a hole on the side where the piston is located. (Some millimeters up). The oil now flows through this hole, past the damping adjustment needle through the tube and into the open oil bath cartridge.
Itīs now clear that the damping adjustment at the top of the fork regulates the oil-flow when the fork moves out.
IMPORTANT: The nut which holds the piston needs some loctite glue!!!
I hope I give you a short overview about the damping adjustment of the 866 Dragster.
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