The following is from a article I wrote on our site. It pretty much explains the way Hunterworks is clutching the XP 900!!
Link to clutch kit on our site plus more info
A link to it but the info is below.
Link to article
Clutching the XP 900 and RZR 800 the Hunterworks way!!
Let me first say this is going to be lengthy to read but I think you need some understanding about clutching the way we are going to do it. Also I am talking about the XP 900 mostly but kits are made for the 800 and 800 S RZR and same information basically applies.
Hunterworks is not new to clutching, we have our own clutch parts for the Rhino, been using and supporting Dalton clutch kits on the Teryx for several years but I have to admit when I wanted to do something with the clutching on our own Polaris XP 900 and I went to the internet I was just thoroughly confused at all the options all the set ups etc. I mean I felt like a dummy but I was thinking, “Why would this be any different than any other vehicle?” In hind sight it is not that difficult nor is it that much different than any other vehicle. Clutching is clutching really, what makes the Polaris difficult I guess is Polaris themselves changes things so often which calls for different parts. Most of what they do is just to save money. Just look at the secondary sheave they did put in the 08 and some 09 RZR’s they were the HD design they use in present day HD Rangers, only the HD ranger has it now, it cost more and it had a helix in it for EBS (Engine Braking System), they changed designs and went a less expensive route. Also Polaris used a one way bearing in the 09 S RZR primary for EBS on some of them and it is a option on the 2013 LE model.
While on EBS let me explain it as it applies the XP 900 and for the most part any of the Polaris line. Every vehicle has engine braking as long as there is enough RPM to keep the primary clutch engaged, the engine braking we are talking about with the EBS is when engine RPM drops enough for the primary clutch to disengage then free wheel. The XP 900 has engine braking below this point thanks to the EBS notch in the helix on the secondary sheave. In my opinion and many others there is too much of this low speed braking and it more noticeable when jumping cause we all let off the gas when we jump and back on it when we land so we don’t break a axle etc. The problem with the XP is it is just too severe and it will just about throw you through the windshield at times and it is rough on belts and axles too due to its abrupt stop while in the air plus it is just irritating. The low speed EBS is very helpful if you ride down hills a lot where otherwise you would be freewheeling and using your brakes heavily.
So your options with us on EBS and our custom angle helix is we will offer a less EBS model and a non EBS model. Who needs either? In my opinion, most will need the less and people who ride extremely aggressive like cross country racing like we do or jump a lot and don’t need the downhill engine braking will want the non EBS helix. Since it is easy to change you might wind up getting both and trying them out. Keep in mind what works for one guy might not work for another. To keep from confusing you worse, if you don't need nor want EBS and you have a RZR 800 or Ranger 800 then do NOT buy anything for the secondary.
Helix angle: We have a custom angle decided on during in house testing. Anyway, Polaris on the XP has a compound angle, meaning the angle starts off one angle and finishes another. The helix angle determines at what rate the secondary sheave opens in response from the primary and it is torque sensing too. Not an article about helixes themselves, heck it even confuses me. But Polaris uses a steeper angle and then a shallow angle. What I found during testing was shift speed was dropping off from the peak by a 100 RPM or so at a slow rate. I found this to affect how crisp throttle response was in the higher speeds and made the vehicle lazy really. So we don’t change angles, we have a straight cut and now our RPM is staying flat during shift speed and actually tipping slightly up. It is very easy to figure this out when you have a chassis dyno like us, using a stop watch and a radar gun can’t give you the feedback you really need.
The Dalton Clutch kit:
When I first needed a clutch kit for my own XP 900, Dalton had not come out with one yet. I needed one because I had put 26x9x12 tires all the way around and my shift speed RPM was at the rev limiter of 8500 and I was hitting it before top speed. If I let off the gas it would ease up there. This told me I needed to make my flyweights heavier. I used the Rooster Weights from Team Industries as it was all I had. That is where the confusion sat in; I had to have the R&D guy there help me with the weights to get it right. What I got from them was three weights and box of washers and screws to make the adjustments. I am NOT knocking their stuff, it worked fine. Who it is really for is for someone who will preset up your clutch kit for you for the exact mod you have and send it to you or you really like to play with your clutch. Again, I am not knocking their product it is just does not work with the way we want to do things. I got it going and it worked well, I got my shift speed down to 8200 where I wanted it and the XP seems happy at that RPM. Like I said, it was complicated and by looking at other people who sell these kits and all the info you have to give them to get the right set up proved it was complicated. That method also has you going back again and again to that guy for a set up when you made some change to the vehicle like smaller or bigger tires, engine mods etc. As my mom says, “That is too much sugar for a dime”
Fast forward to now, Dalton offers their clutch kit for the XP and all the RZR 800 models with a set of adjustable flyweights and a primary spring. What is different? The Dalton flyweight has a threaded hole you screw up to three set screws in to add weight in them. They also have a hole in the end of the tip to attach a weighted rivet into to change things. So how are you going to know how to set it up? EASY!! It comes with a nine page manual with an array of set ups that match most people. It’s so easy even a caveman can do it! Best part is you can rest assured Dalton has the flyweight contour figured out for fastest acceleration and coolest belt temps.
Do you need a secondary spring change? With this set up, not unless you are running heavy 28” tires or the 29.5” or larger tires then there is the optional stiffer spring for better belt grip and better upshift. There is also set ups in the manual for the spring too.
Cool part is, you can make the adjustments with the set screws while the clutch is still on the vehicle, and I did it when testing.
With our custom helix, we found we needed a tad bit more flyweights weight so if the kit calls for two set screws, you add a short set screw. The kits come with long and short set screws. If your set up calls for two long and one short then you run three long with our custom angle helix.
So who needs a clutch kit?
The real truth is, anyone who makes some mod like bigger or smaller tires or engine mods will NEED to do this or they will get less than ideal performance results. Go bigger tires, you need lighter weights to counter act the loss in RPM, go smaller like I did then you need heavier to bring RPM back down. Engine mods require both at times depending on what you are doing. Dalton or Hunterworks does not address engine mods because the flyweights needs vary so much and you will have to rely on them for that but at least you have something you work with.
What does a bone stock guy with stock tires get out of this? A slight pick up in acceleration, better throttle response, more positive belt engagement which means longer belt life. The totally stock guy has the least to gain, the other guys with mods just really have to do it.
The helix part of it is for anyone and you can just change a helix to change the EBS we mentioned to something better for you and get the benefit of our custom angle too. A helix only change affects on the XP 900 owner or someone who has swapped over to the HD design secondary. Everyone else can't just swap a helix out.
I will tell you there is a dozen ways to skin this cat and with any of them, best to worst set up is not a white knuckle experience. Don’t get caught up in splitting hairs either, you will drive yourself completely crazy thinking you can make it better. You will have to have a dyno yourself and other equipment to show it is better because your “Butt Dyno” will not be able to tell the difference. Is this set up is a little more expensive than the other set of flyweights and a helix? Yes but this way is much easier for you to do and really not that much money difference. Our way of doing it will just fit most people, some will need something totally different all together but this fits most and is too easy to do. If you are unsure whether this will benefit you or not, feel free to call and we can discuss it.
XP 900 owners:
The set up has two to three parts. The Dalton clutch kit for reasons mentioned, a change in helix to get less braking or no braking for racing plus our custom angle and then a secondary spring change for 28" and larger tires
RZR 800 and S owners:
The Dalton clutch kit only and depending on tires size as to whether you get a secondary spring or not in the kit ordered and possibly replacing the whole secondary as long as you do NOT have a 08 or early 09 model which has this secondary already so you can have our custom helix and the EBS if you need low speed engine braking.
BTW, the primary clutch puller is almost needed to do this, lots easier to remove the primary and install the weights than to do it on the machine, adjusting them on the vehicle is easy though.