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Changing Rear Sprocket

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I have 2012 KTM 350 XCF...  I have 50 tooth rear sproket right now.  It rides pretty good in the trails and lugs down pretty decent. I would like to change the rear to a 52 tooth.  I am hoping to be able to make it more luggable (tractorable) in tight spaces, also hoping to run more in 2nd gear.  But my main question is if I change to a 52 sprocket (I know I will get more torque and less top end, which is fine, I never go faster than 4th gear.) will it create more wheel spin if I gas it.  

 

For example if I were to give it 1/4 throttle up a hill with the current settings 14/50 and it lugs to the point of dying, but the rear wheel wont loss traction and spin freely. If I were to go to a 14/52 and go up the same hill and give it 1/4 throttle will the bike lug up the hill better (it should) but will it loss traction easier. 

 

I'm thinking it will take longer for the rear tire to spin, but you will get more grunt out of the bike.

 

Thanks for any info.

 

 

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if the traction is real good it will hook up and wheelie easier. If the traction is low it MAY spin the tire more easily. It will also not lug down and run out of power as easily.

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Are you sure it has 14/50 gearing? My 2011 350XCf came with 13/50 gearing. I ended up moving to 13/51 and am still running that today.

No sorry I am not 100%, your probably correct it is most likely 13/50.  What did you think going to the 51? would you possible go to a 52? I believe every tooth in the back is roughly a 3% change in gearing and 1 tooth in the front is about 7-8%

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Same bike and run 13/52. I ride mostly 2nd and 3rd gear and very rarely stalls on climbs. I ride pacific northwest trails. Also your back tire has alot to do with traction, i use a 120/80 dunlop and it works well. The 350 is not a lugger regardless, they like high rpms and higher speeds to work well.

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No sorry I am not 100%, your probably correct it is most likely 13/50.  What did you think going to the 51? would you possible go to a 52? I believe every tooth in the back is roughly a 3% change in gearing and 1 tooth in the front is about 7-8%

I think the slight change from 50 to 51 on the rear helped make 3rd gear more usable at really slow speeds. Just a bit of a blip of the clutch coming out of corners and you can be back into the meat of the power pretty easily with no gear changes required.  I wouldn't gear it down any lower for my preferences, 1st is a very slow gear, i'm not sure you'd ever need a slower gear no matter how difficult the terrain is, its mostly about clutching at that point.  I also have a full fmf megabomb 4.1 system on my bike, not too sure how much of a difference that makes.  It probably adds 1 or 2 hp, but that's about it.  The 2012's didn't have the chocked up muffler that the 2013+'s have with the baffle, so your exhaust should be very good for power, even stock. (if that's what you have)

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Same bike and run 13/52. I ride mostly 2nd and 3rd gear and very rarely stalls on climbs. I ride pacific northwest trails. Also your back tire has alot to do with traction, i use a 120/80 dunlop and it works well. The 350 is not a lugger regardless, they like high rpms and higher speeds to work well.

I also ride the pacific northwest trails, the bike came with a Michelin 140/80 (a little to big) rubs slightly on the exhaust as soon as it wears down I'll be changing it out for a 120 also. I was surprised how well it does at lower rpms, I'm use to riding mx bikes through the trails and having to clutch quite a bit, on the 350, it was changing my riding style and I noticed I didn't have my fingers on the clutch, I only stalled it twice at my ride at Walker Valley.  But I would agree with you, the faster I went through the trails the better the bike handled. If your riding 2nd and 3rd gear in Washington (The westside) your a pretty decent rider then. :)   I have track at my house, it does really well there.   I didn't realize there was two different bikes the XCF and XCF-W.  I was trying to go with the XCF-W because I already have a track bike, so I now make the 350 more rideable on the tight trails, I know on more open trails it will be flat out a blast.

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I think the slight change from 50 to 51 on the rear helped make 3rd gear more usable at really slow speeds. Just a bit of a blip of the clutch coming out of corners and you can be back into the meat of the power pretty easily with no gear changes required.  I wouldn't gear it down any lower for my preferences, 1st is a very slow gear, i'm not sure you'd ever need a slower gear no matter how difficult the terrain is, its mostly about clutching at that point.  I also have a full fmf megabomb 4.1 system on my bike, not too sure how much of a difference that makes.  It probably adds 1 or 2 hp, but that's about it.  The 2012's didn't have the chocked up muffler that the 2013+'s have with the baffle, so your exhaust should be very good for power, even stock. (if that's what you have)

Yes I have 2012 exhaust and its good for power, I need to change it out though for a exhaust with a spark arrestor, Yes 1st is very slow, I was kind of hoping to eliminate 1st unless I need it for really really tight slow stuff. 

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My '14 350XCF stock gearing was 14/50, which is tall. For tight technical singletrack I run 13/52 which is a perfect setup for me. My buddy has same bike and was running 13/50. He rode my bike for 5 min and ordered a 52 rear. I doubt I'll change it for anything other than open desert....maybe?

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I'm thinking it will take longer for the rear tire to spin, but you will get more grunt out of the bike.

 

 Not quite. More torque yes, which will spin the rear more quickly faster. Unless you can ride up a gear, in which case you will be going faster and spin less.

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Also I added a KTM power parts mapping switch. Allows you to lug or blast, less than $100 mod. I think it's a must have

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Update, I ended up buying a 12t front sprocket, it was cheaper to do testing and it gave me more of an extreme sense of what it would be like if I increased the rear sprocket.

You can now put it in first with no gas and it will continue to keep moving even at a slight incline 3/12 pitch. So first gear will be great for really tight stuff, second gear is so much better, you can really get it low before stalling, but has good speed through the gear before needing to shift.

When it comes time to change the sprockets and chain, I think I will go back to the 13t front and 52 rear.

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Update, I ended up buying a 12t front sprocket, it was cheaper to do testing and it gave me more of an extreme sense of what it would be like if I increased the rear sprocket.

You can now put it in first with no gas and it will continue to keep moving even at a slight incline 3/12 pitch. So first gear will be great for really tight stuff, second gear is so much better, you can really get it low before stalling, but has good speed through the gear before needing to shift.

When it comes time to change the sprockets and chain, I think I will go back to the 13t front and 52 rear.

The problem you run into with a smaller front sprocket is that it will wear out much faster due to the increased torque on it to turn.

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i had a 14/51 and i wasnt comfortable on my bike at all...Swapped the rear sprocket for a 48 and it drastically calmed her for me. Still can do tight turns and maneuver in the sand, so i am happy...

 

Also swapped the 80/90 front tire for a 90/90 and the rear 110/90 for a 120/80. Hopefully with the wider tires i can float better across the shifting sands...

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