Polaris ATV Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
36 Posts
Discussion Starter #1
I have been trying to get my 2012 500 HO dialed in for the 26" mud tires I put on it and am trying to do without having to install a full aftermarket clutch.

I replaced the Blue/Green OEM primary with an EPI Red. I like the higher engagement ~2200 RPM, but felt like the RPM's were too high at a full throttle take off ~6600 - 6800 (like the belt was slipping in the primary before the clutch weights kicked in). I then put in some 49.5g primary weights 10M5 to replace the factory 46g 10WHF weights.

The sensation of belt slipping went away and now I can lift the front end much more easily (in High). However now the full throttle RPM's are ~6200, which makes sense as rule of thumb is about 150 - 200 RPM per gram of weight.

I would like to let the engine rev out a little bit more before upshifting, while maintaining a more positive belt tension (perhaps by keeping the belt higher in the secondary sheave for longer. Currently the secondary spring is factory.

What is the stock full throttle up shift RPM?

Is there any adjustment on the secondary that could add more pretension to the spring considering it is currently stock?

What is the factory secondary spring rate? Would an EPI Orange or the Purple secondary make an improvement over stock?

Thanks!
 

·
Registered
Joined
·
5,753 Posts
Can't help you on the spring rates as I don't have the stock ones to compare to. But if you don't have EBS, then you can tighten up the secondary spring one more notch from stock. Stock is holes 2-2, go to Helix 2 sheave 1 and see how that works. That is likely all you had to change to start with, and now are about $40 from just getting a custom kit complete anyway. To get your RPM back up, you need to add finish rate to the primary spring. 67-6800 is a good place to be.
 

·
Registered
Joined
·
36 Posts
Discussion Starter #3
Can't help you on the spring rates as I don't have the stock ones to compare to. But if you don't have EBS, then you can tighten up the secondary spring one more notch from stock. Stock is holes 2-2, go to Helix 2 sheave 1 and see how that works. That is likely all you had to change to start with, and now are about $40 from just getting a custom kit complete anyway. To get your RPM back up, you need to add finish rate to the primary spring. 67-6800 is a good place to be.
Thank you for your reply.

I will try tightening up the secondary one more notch to see if that helps. It may make sense to go back to stock weights if an adjustment on the secondary is all it needs.

I did neglect to note that with the stock weights and Red spring I had a hard time going above 40 MPH.

I'm only about $45 into my clutch work. $20 for the EPI spring and $25 for some second hand 10M5 weights.

Thanks!
 

·
Registered
Joined
·
805 Posts
You can lighten those weights up a bit too. Just get a scale and be sure they are all matched. As ridinagain said, you dont need to rev a stock 500 more than 6800. I find they are best right around 66-6700.
 

·
Registered
Joined
·
13 Posts
I know this is resurrecting an old post but I am in a similar position as CTGT2005. If you are still around, what did you end up with for your clutch setup?

I have a 2013 Sportsman 500 HO with 27" Kenda HTRs and will be installing a EPI Red primary spring tonight.

I don't care about top speed much - if it would do 45mph top speed that'd be just fine.

I do trail riding and a little mud but am looking for front end lifting and acceleration while still being manageable on a steep hill/rocks without flipping over backward.

I found a site that sells clutch weights for $50 for the set but I'm getting confused if I should go heavier or lighter for my application or just adjust the secondary since mine is non-EBS.

Thanks!
 

·
Registered
Joined
·
36 Posts
Discussion Starter #8
I know this is resurrecting an old post but I am in a similar position as CTGT2005. If you are still around, what did you end up with for your clutch setup?
With the Red EPI spring alone and HD Belt I liked how fast the engine took RPMs but there was a sensation of belt slipping and heating in the secondary. I also felt like I lost way too much of my upshift and the machine limited itself around 45mph.

Where I am now

Went with a 50.5g weights, Red EPI primary spring and stock black secondary on setting 2 - 1 (Stiffest Setting).

Ditched the Kenda Executioners for Maxxis Zilla's all around.

I am turning just around 6600 RPM across the board, down from 6900 RPM with just the EPI red spring and all stock.

With the heavier weights I would go with a spring with an initial force rating slightly higher than the EPI red and leave the finish rate alone. I am considering grinding the heel on the weights to reduce some of the initial force for harder take off or swapping out the spring.
 

·
Registered
Joined
·
13 Posts
Thanks for responding! I didn't know if anyone would still get updates from this post after 7 months.

Could you tell me what riding characteristics you noticed differently from when you had just the RED EPI primary installed vs with it AND the heavier clutch weights?

Also when you say:
With the heavier weights I would go with a spring with an initial force rating slightly higher than the EPI red and leave the finish rate alone. I am considering grinding the heel on the weights to reduce some of the initial force for harder take off or swapping out the spring.
does that mean you would go with lighter than 50g weights if your running the Red EPI primary?

I have read a bunch about cvt clutching but it seems like i've come to a point that I need to ask questions. For instance, of the primary spring and clutch weights control the rpms, what is the difference between light spring and light weights vs heavy spring and heavy weights? Is it just the amount of belt grip? (not 'just', I know it is important)

Thanks again!!
 

·
Registered
Joined
·
36 Posts
Discussion Starter #10
Primary weight and primary spring are roughly equal opposing forces. Your shift characteristics is the net of the two forces. Increasing weight has the same effect as decreasing spring tension. If you had stock weights I would go to a spring that has same start rate and lower finish rate. I think the epi red is 40/140. Using stock weights I would look for a 40/125 or so just to give a bit more rpm off the bottom without hurting shift out too much.

The problem was I couldn't find a spring that had that rate to use with stock weights. Having heavier weights gives more tuning options.

The secondary clutch applies a resistive force to the primary clutches attempt to upshift. This causes belt tension/grip and will also have an impact on the rpm at which the clutch shifts. A stiffer secondary spring or setting will keep the belt riding higher in the secondary clutch sheaves giving a greater mechanical advantage to the engine at a higher rpm. With bigger tires you need to have your secondary tighter to squeeze the belt more and/or swap your helix in the primary.

Remember I'm also using a stiffer secondary setting and gates gforce heavy duty belt. Both these factors cause the rpms to want to be higher. Noticed the gates belt also caused an increase in shift out over a stock belt. I think the rubber compound is a bit harder and less flexible. The heavier weights helped bring the rpms back to where they should be. I am still tweaking this setup and will likely swap springs again to one with 10 to 15 more lbs off the start but it's right where it should be up top.

Always happy to help out.
 
1 - 10 of 10 Posts
Top