Trxster
TY 4 Stroke Junkie
21/40 might give you better top end on the trail.....but even that is debatable. It is a wrestling match between the power the motor produces....and the resistance from the track (traction, gearing, track length, etc). That wrestling match occurs in the clutches. If you are geared too tall, then the power of the motor might see the primary ride up high enough to pull the secondary down to a 1:1 ratio or close to it. However, if you gear down a bit, say 20/40, now the primary might be able to wrestle the secondary down to an overdrive ratio.
This will be especially evident when climbing a big hill. You will often see your sled start out at 10,200 rpm but as it climbs it starts bogging down a bit and might drop to 9000 rpm (that is what my sled did with 21/40). Imagine trying to pull the pass in 6th gear in your truck while towing a trailer-you will lose rpm's to the point that your speed will slow to 35mph!!!! However, if you drop down to 4th gear, you can keep your rpm's up and it helps keep you in the powerband and keeps you at 45-55mph.
Each sled is a bit different and you won't know until you try it on your sled but typically a small gear down will not lose you too much top end (maybe 3-4mph) while allowing better acelleration and will maintain rpm's better while climbing. So, you might drop to 20/40 or 21/42 and see how it affects your top end. You will definitely like it better for boondocking and climbing and will probably like the quick accelleration when lake racing.
Here is a great experiment.....take your belt off and take a black grease pen and make some straight lines on your clutches. Put belt back on and do some WOT runs (either climbing or not). Then look at your clutches and see how high your belt runs in the primary and how low it gets pulled in the secondary (where the belt runs it will erase the lines). If you are leaving 1"-1.5" on your primary, you are leaving performance on the table that some clutching or gearing might help fix.
Good luck.
Rt
This will be especially evident when climbing a big hill. You will often see your sled start out at 10,200 rpm but as it climbs it starts bogging down a bit and might drop to 9000 rpm (that is what my sled did with 21/40). Imagine trying to pull the pass in 6th gear in your truck while towing a trailer-you will lose rpm's to the point that your speed will slow to 35mph!!!! However, if you drop down to 4th gear, you can keep your rpm's up and it helps keep you in the powerband and keeps you at 45-55mph.
Each sled is a bit different and you won't know until you try it on your sled but typically a small gear down will not lose you too much top end (maybe 3-4mph) while allowing better acelleration and will maintain rpm's better while climbing. So, you might drop to 20/40 or 21/42 and see how it affects your top end. You will definitely like it better for boondocking and climbing and will probably like the quick accelleration when lake racing.
Here is a great experiment.....take your belt off and take a black grease pen and make some straight lines on your clutches. Put belt back on and do some WOT runs (either climbing or not). Then look at your clutches and see how high your belt runs in the primary and how low it gets pulled in the secondary (where the belt runs it will erase the lines). If you are leaving 1"-1.5" on your primary, you are leaving performance on the table that some clutching or gearing might help fix.
Good luck.
Rt
Jabber
Extreme
- Joined
- Dec 24, 2005
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- 2017 Sidewinder mtn 162
Culvert, I am running the same weights as you. 8bu-10 with 10.3 alum. rivets in both holes. 90% of my riding is between 5000 & 8000 feet in 2 to 3 feet of powder. I pull a steady 10,100 rpm whether I am hill climbing or boondocking.
Trxster makes a good point about gearing and using your clutches. Mark your primary and secondary and see where your belt rides.
Before putting a silver sping in the secondary, my belt was about 1-1.5 inches below the top. It didnt matter whether it was geared at 21/40 or 20/40. Now I am about .75 inch below top at 21/40. I am going to recheck this weekend with 21/40 on sat and 20/40 on sunday. Will let you know.
Trxster makes a good point about gearing and using your clutches. Mark your primary and secondary and see where your belt rides.
Before putting a silver sping in the secondary, my belt was about 1-1.5 inches below the top. It didnt matter whether it was geared at 21/40 or 20/40. Now I am about .75 inch below top at 21/40. I am going to recheck this weekend with 21/40 on sat and 20/40 on sunday. Will let you know.
