Primary Spring 120/310 vs 140/310?

[nwoprormk]

Hi I have a 12 SBA that came with the 120/310 with 10-66 for my elevation.Question is what will change to go to a 140/330 ???
Thanx In advance cory

 

[nwoprormk]

Hi I have a 12 SBA that came with the 120/310 with 10-66 for my elevation.Question is what will change to go to a 140/330 ???
Thanx In advance cory

Manual says to use the 140/330 for 6-10k elev. Can I use it at 2000' if I run 10-68's instead of 10-66's....to keep the rpm down on top?

 

[d8grandpa]

Hi I have a 12 SBA that came with the 120/310 with 10-66 for my elevation.Question is what will change to go to a 140/330 ???
Thanx In advance cory

The low number is clutch engagement rpm, the high number is peak rpm. Each increment of 10 of the spring number equals roughly 100 rpm, so the 140/330 clutch engagement will be 200 rpm higher and the peak rpm will also be 200 rpm higher as you raised both numbers the same. That's provided you have same clutch weights and riding elevation. You can get springs to change either upper or lower numbers you don't have to change both, there is a lot of combinations.
good luck.

 

[nwoprormk]

rode it yesterday.....woke the sled right up. Almost to the point it seems that it is not the same sled. I was worried it may over-rev so I added the 10-68's instead of the 10-66's (correct for my altit with the lighter spring).....Had tons of snap once it ramped up...but seemed to have no load at one constant speed. It possible the heavier weights caused this....kinda holding back the clutch from coming together? Really liked it once I got on the gas....but not so much at cruising.

Thinking this spring was hooped for long time....just didnt notice it slowly getting weaker as the miles racked. Currently at 1625....

OH BTW..... the engagement changed by lots....7-800 rpm ( that's why I think spring had issues)

 

[HotShotHarry]

You can buy a Glide Washer Kit from Thunder Products. $15. It comes with 2 glide washers that you put on either side of the primary spring. This will stop the spring from gouging into the spring cover. The kit also comes with washers that you can install. each washer added will increase the engagement RPM by 50. You can keep adding washers as the spring weakens over time if you so choose.

 

[Ryan Verrecchia]

If you have it stock you should just get gold star adjustable weights easiest way to tune it for elevation. And for spring just stay with what they recommend for springs unless you want to have it set up for what you want.

 

[Teth-Air]

I run the softer 120 spring in my 800 with my clutching (600 SPRING) I like it better than the 800 spring as I like lower engagement.