Clutching help

[titanrcr]

Correct me if I'm wrong but doesn't a lower/shallow angle increase rpm?

Yes it does

 

[newtron]

Yes it does[/QUOTE

Whats the stock helix on xtx?

 

[titanrcr]

Not sure

 

[newtron]

rtx is 43 so xtx must be lower than 40 I'm assuming

 

[titanrcr]

Not sure

 

[Studroes144]

Parts finder says 8bv31 which is stock 43 helix like ltx and rtx.

 

[newtron]

so I don't think going to a 40 finish will lower rpm....according to the technical pages I have read on this site

 

[STAIN]

You are right. The lower the finish angle the higher the RPM. That's why a lot of the old clutch kits would throw big weight to grab hard on the bottom and then run a crazy helix like a 58-40 to get the RPM's up on the back side.

 

[STAIN]

You are right. The lower the finish angle the higher the RPM. That's why a lot of the old clutch kits would throw big weight to grab hard on the bottom and then run a crazy helix like a 58-40 to get the RPM's up on the back side.

 

[NOS-PRO]

43° is stock for an XTX

 

[NOS-PRO]

Finally got a chance to ride in the UP this past weekend and the clutching was great down low as the acceleration felt better but my issue is on the top end I'm hitting the rev limiter (9200) at around 80 - 85 MPH. I've got a GWG spring with a 2mm spacer as well as the 8FP weights and a 17.2mm steel rivet in the tip. Off the line when punching it, it comes up to 8700 - 8800 and pulls well but you can feel it start cutting out and the tach is running over 9100 as you get around 80 MPH The middle and heel holes are empty, do I need to add weight to the middle hole? If so, any idea how much?

I would add 2 grams to the middle, leave the shim(s) and try it.

Little steps at a time nherbst

 

[shagman]

so I don't think going to a 40 finish will lower rpm....according to the technical pages I have read on this site

The problem here is the fact that he was running a setup with only half the parts. Did not change helix, only changed weights and primary spring. Yes less angle will produce higher rpm. But the reason the rpm's are high in this instance is that there is not enough force in the primary to shift out completely and this causes belt slippage in the primary. Hence only 80-85 mph. If the correct helix is put in 46/40 the primary will no longer slip and the rpm's will come back down where they should be. It takes less force in the primary to pull a lesser degree helix to full shift on top end.

 

[1049triple]

Still haven't try the 46\40 helix, but I ordered it without any hesitation and will be home tomorrow.
Every set-up I tried including different weights profiles would have work better with the 46\40 helix. The 51\43 is a bit too aggressive and didn't give the top end rpm's I was shooting for (9100). The 46\40 will be the best for me by getting rid of the starting over-rev, and pulling the right rpms up top!

 

[newtron]

Still haven't try the 46\40 helix, but I ordered it without any hesitation and will be home tomorrow.
Every set-up I tried including different weights profiles would have work better with the 46\40 helix. The 51\43 is a bit too aggressive and didn't give the top end rpm's I was shooting for (9100). The 46\40 will be the best for me by getting rid of the starting over-rev, and pulling the right rpms up top!

If you keep the same setup with your 51/43 I think it will over rev more if you change to the 46/40. I had that helix last year but was hard to stay off the limiter with the weights I use loaded in the heel. Switched to a 49 start and is good now. Less starting angle will give you more rpm in your hole shot.

I'm running a stage 1 turbo by the way

 

[1049triple]

With stock weights, spring and helix, hit the limiter on a start. With the 51/43 at 6-2 I had to run the b-w-b primary spring to keep the rpms at 8700 on a lunch, but engagement was too high at roughly 4300, so the sled was not as smooth as I wanted. That's why I know the 46\40 should work for me, even with the 8GL.