I wrote this up a good while ago for my personal site. Take the info for what you will. I added some updates to this as well.
This information was gathered by a lot of members on various forums so I'd like to give credit where credit is due...Dustin (Blackie) @ EKO Racing, Brian (wppracing) @ WPP Racing, Morgan (DemonIndustries) @ Demon Industries, Michele (quadmom) @ RAGE ATV Racing, Corey (#8TRX450R) @ ATV Tech, Gerry (El Duner) @ ATV Tech, and Mark (mwsartain) @ TRX450R.org.
Part numbers:
Standard CR500R - 22401-ML3-910
Taller CR500R - 22401-KA5-740
Standard 250R - 22401-HA2-670
HD 250R - 22401-HB9-770
CRF450R - 22401-KZ3-690
Where to buy?
- TUSK brand springs - Rocky Mountain ATV MC web site.
- OEM springs - Service Honda web site using the part numbers supplied.
- Dark Synergy springs - They have now been rebranded several times...performance spring, and have now been bought out by Tokyo Mods (so I hear).
Dark Synergy Springs
Verbiage taken from Dark Synergy's old web site: Operating Range over 200 degrees F higher than the best OEM clutch springs. Engineered with the lowest possible spring rate for a smooth pull and positive engagement, and with the precise installed pressure needed to ensure minimal clutch slippage. Extends clutch life and Improves clutch performance. No more clutch fade! Outperforms OEM and aftermarket clutch springs. Lifetime warranty!
...FYI, Dark Synergy changed their name to "Performance Spring." I've heard that they no longer make ATV Clutch Springs...and their remaining stock was sold to Tokyo Mods. I had also heard that the DS "MOD" springs were actually DS LTR-450 springs. However, I ordered a set of Tokyo Mods LTR-450 clutch springs and they were not the DS "MOD" springs...they were much shorter...and I'm not even sure if they have the same heat resistant coating, etc.
HD 250R Springs
I've heard mixed reviews on the HD 250R clutch springs...some have said they cause coil bind and need to be modified to fit...others say they are a drop in spring...but everyone has said you're left forearm will look like Popeye's after using them for a while. I wouldn't recommend using the HD 250R clutch springs unless you have a lockout.
My Clutch Setup & Experience
Currently, I'm using an OEM '06 CRF450R clutch in my bike along with the High HP (MOD) Dark Synergy clutch springs. The CRF clutch was recommended to me by RAGE. Michele told me that the CRF clutches have a thicker inner and outer fiber and they hold up well on their builds...and we all know RAGE can build some power. Note: there is no judder spring in the CRF kit. I purchased the CRF clutch kit on eBay for $135 with shipping (also available at Service Honda) and the High HP Dark Synergy springs were $60 with shipping. I've gone through one OEM TRX450R clutch and two Tusk clutches in my bike, so paying a little more money for a setup that should last was definitely worth it to me. 95% of the riding I do is on pavement where there is a constant load on the bike. The CRF clutch with High HP DS springs seems to be holding up well with my mid 50's HP stock bore/stroke build.
^^^Update on the paragraph above...after 3 years of abuse (didn't ride all that often, but thrashed it pretty hard when I did), the CRF clutch fibers and plates were smoked...clutch basket is also notched. A brand new OEM CRF450R clutch will be going back in it, along with a Wiseco Forged clutch basket...and I haven't decided if I should keep the old DS MOD springs that are 3 years old, or go with the newer Tokyo Mods LTR-450 clutch springs that I had ordered (shorter than the MOD springs).
My Dad is using a RMATV TUSK clutch in his bike with the Standard Dark Synergy springs. His clutch is a bit easier to pull and has been holding up well with his build (mid-high 40's HP stock bore/stroke).
We run red bottle Honda HP 80/85W transmission oil in both bikes.
CRF Clutch Part Numbers:
Below are the part numbers for the OEM 2006 CRF450R Clutch. The clutch kit (06001-MEN-001) comes with everything needed. I provided the part numbers for everything that is contained within the clutch kit in case anyone wanted to buy the parts separately.
OEM CRF Clutch and Parts
Part Description Part Number
(1) 2006 OEM CRF Cutch Kit 06001-MEN-001
(6) Clutch Springs 22401-KZ3-690
(8) Clutch Friction Disks 22201-MEB-670
(7) Clutch Plate B 22321-KZ3-690
(1) Clutch Cover Gasket 11352-MEB-671