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‘21 Mule SX XC
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Discussion Starter · #1 ·
Hello all, brand new to this forum and just picked up 2021 used Mule SX Camo HC FI (KAF400S). So far so good, started at -18C (0F), drove thru foot of snow in yard with unlocked rear diff and 4x4, no issues.

In reading specs in owners manual pg 16 it indicates different “transmission” gear ratios on the models that have the XC 12” rim and 26” tires. It also lists “overall“ drive ratios so anyone know if Kawasaki actually revised some gears to accommodate the larger tires. I checked some part look ups on the R/S/T models vs KAF400P base model with 10” rims and 24 tires but couldn’t find where the gear ratio difference was. I was considering a taller tire upgrade 27/28 to gain more clearance but now questioning whether that’s a viable option. At 0F driving down lightly snow covered road other day it seems like low range was close to same top speed, just higher rpm. I was in 4wd and nothing seemed odd just no more pedal room on hi range lol. Thinking it was pushing the 13 hp limit and didn’t have any umph left to get it up to the 25 mph speed, motor wasn’t lugging just less rpm. I’m sure if I aired up tires to spec and warmer out it would be fine. No matter I’m happy thus far as I didn’t buy it for speed, bought a 60” plow that links to rear hitch so fingers crossed it has enough power to push that around, haven’t installed it just yet.

Cheerios
 

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Muler,
I've wondered the same thing about swapping the gears from an XC model. I bought a brand new 2022 Mule SX 4x4 and wish it had more low end power when using the machine in very hilly terrain. I also saw the gear ratio differences in the owners manual and it would only make sense that it would be a simple gear set in the transmission that they revised for the larger tires on the XC.
 

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‘21 Mule SX XC
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Discussion Starter · #4 ·
Yeah I’ve been looking at the gear part numbers when I’m looking at part diagrams but haven’t found where the difference is. I would be impressed if Kawasaki engineered it in order to maximize the little 401 cc performance. Perhaps it’s in the clutching that they get a different ratio, not sure but suspect revised tranny gears would be a bit more costly in design work but again just a guess. I was considering tire upsize to 27“ or 28” simply for ground clearance, didn’t want to sacrifice any more low end torque but 28” would sure be nice in the rutty trails. Will need to climb steep bank in summer, previous quad did leaning over front bars, hopefully mule will, seen some good videos, just doesn’t appear to do anything rushed….like a mule, suits me fine, I move like sloth now anyways lol
 

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Kawasaki surely wouldn't change the front and rear diff gearing, that would be too much expense. Maybe the clutching on the CVT is different.....that would be an easy upgrade if so. I installed a cheap tachometer the other day and noticed it idled around 1200 rpm. The full throttle rpm (governed) is around 3400. This means there is only 1200 +- of usuable RPM range and therefore Kawasaki would gear the machine higher so they could achieve a decent top speed (25 MPH). This hurts the bottom end pulling power in return. I'll stop by my local Kawi dealer sometime and see if I can get any info from them about the difference in gearing.
 

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‘21 Mule SX XC
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Discussion Starter · #7 ·
I hear ya, just 13Hp to work with makes it challenging to accommodate accessories or mods.
i’m just doing same, 3-3/8 faria 4K diesel tachometer on order along with some 2” tractor gauges to monitor oil and fuel pressure along with bat voltage and +/- ammeter. Unfortunately no shop yet so won’t be doing install till it warms up. Did you tie tach signal to coil +? …hope it works, haven’t recd yet.
i saw a video of guy posting how to turn up governor, I read specs on engine and its max rpm was listed at 4000, max hp at 3600, maybe bump up the top rpm to 3800 to get‘er into the running speed. Funny, now I picture 13 hp tied to a cart to get a sense of reality.
 

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Discussion Starter · #9 ·
I myself would prefer your set up for tach signal, simple and not wiring into engine electronics. i like fuel injection but it does require computer intervention and sensors…time to invest in service manual. Been looking for a late model Mule SX wiring schematic but not so easily found.
 
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