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Would that not require a shortening of the chain?
It did not on mine. My 15T was actually fitted at a dealer - took 10minutes ( it was a "i'll do it now if you want" thing) - Was 1 flat (1/6th turn) on the adjuster screw. Yes - they let me watch.

I'm not sure I'd want to shorten gearing much more. I do some motorway work and if it were much shorter I think it would be too revvy. I'm off out in 20 mins or so, and I'll make a note of the KMH:RPM ratios in 5th and 6th. At about 5Krpm. OK?
 

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Would be great if you could. If I'm forced to do motorway work I'll cruise at an indicated 75 to 80mph. I'm guessing it'll be in the 5-6k rev range, which I'm happy with. Rarely use anything above 4th on an A or B Road so not fussed if the revs are higher in those gears as it's rarely held at one speed
 

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Ordered the KTM front sprocket today. I had to check there was no problem with clearance getting the sprocket off - I had to loosen the swing arm pivots on my 1190 Adventure just to get the sprocket off as it was too close to the frame rails! And am I right in thinking that the speedo will still read correctly after the gearing change?
 

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Would be great if you could. If I'm forced to do motorway work I'll cruise at an indicated 75 to 80mph. I'm guessing it'll be in the 5-6k rev range, which I'm happy with. Rarely use anything above 4th on an A or B Road so not fussed if the revs are higher in those gears as it's rarely held at one speed
So 5000rpm - about 112kph in 5th - 70mphish - about 124/125kph in 6th - 78mph-ish - indicated. The top gear 5000rpm is close to 120kph (GPS).
The issue is that the rev counter is not all that precise. it goes up in steps (i think 250rpm - maybe 330)
imo even at 1 tooth shorter front - 6th is still a 110kph (70mph-ish) up gear - maybe 60 up if you're trundling.

Would I add an extra rear tooth or even more? - That depends.
If you do much highway riding - NOPE.
If you want to pop more wheelies - probably.
If you want to do stunts - add as many as you feel works. I have seen 59 tooth rears.
 

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Ordered the KTM front sprocket today. I had to check there was no problem with clearance getting the sprocket off - I had to loosen the swing arm pivots on my 1190 Adventure just to get the sprocket off as it was too close to the frame rails! And am I right in thinking that the speedo will still read correctly after the gearing change?
Yup - speed is based on front ABS ring rotation speed.
 

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Might as well throw my 2 cents in. Dropped a tooth up front. Installed a non dampened sprocket only because I couldn't find a dampened in stock. No difference in sound or vibration. Biggest difference in gearing for me are 4th & 5th gear. Pulls hard from bottom to top. Can come into corners a gear higher, and excellerate faster coming out. Bike actually tracks your line smoother. Woke my 790 up a little. Best mod so far. Have piped it, different tires, and played with the air box.
 

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Might as well throw my 2 cents in. Dropped a tooth up front. Installed a non dampened sprocket only because I couldn't find a dampened in stock. No difference in sound or vibration. Biggest difference in gearing for me are 4th & 5th gear. Pulls hard from bottom to top. Can come into corners a gear higher, and excellerate faster coming out. Bike actually tracks your line smoother. Woke my 790 up a little. Best mod so far. Have piped it, different tires, and played with the air box.
@Hookedup01 god info, thanks for posting. This is a bit of a newbie question but can I confirm that you didn't need to change chain length after adding the extra tooth upfront it was just a chain adjustment? Also, my 2 cents worth. I just changed the OEM brake pads for EBC FA244HH and its been a great move. More progressive, better feel and way more bite.
 

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@Hookedup01 god info, thanks for posting. This is a bit of a newbie question but can I confirm that you didn't need to change chain length after adding the extra tooth upfront it was just a chain adjustment? Also, my 2 cents worth. I just changed the OEM brake pads for EBC FA244HH and its been a great move. More progressive, better feel and way more bite.

BTW, he DROPPED a tooth on front, not added.
 

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Dealer has my 15t front sprocket in so I'll pick it up tomorrow. Was going to fit it myself, but have only done ones on my dirtbikes, which tend to have more clearance. How difficult is it to change the front one on the Duke and any tips? I had to loosen the swingarm bolts on my 1190 as the sprocket fouled the frame rails...
 

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How difficult is it to change the front one on the Duke and any tips?
Did mine a while ago. I'm certainly no great mechanic, but don't recall any issues at all. The "trickiest" part was re-tensioning the chain to accommodate the new found slack, and other than understanding KTM's bizarre chain tensioning methodology, that was no great challenge either. It's a great opportunity to have a good clean behind the front sprocket, and de-grease the sprocket cover too. Good luck!
 

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Just picked up sunstar 15 tooth non-damped but I have the damped on the way on back order just in case it's such a pain to get a dealer to do anything around here like they're doing you a favor number one and number two like you're doing something wrong by changing something on the bike they just have bad attitudes I wish I had a dealer like you guys around me LOL so I'm going to do it myself and then I'm going to tighten the chain just the hair cuz it's really loose slapping I watch that bolthole biker guy I've done a few chains in the past but it's been a while I don't know how many you guys watch him he seems pretty good has a good method according to what he says KTM kind of does, but who knows I'm sure I'll be in the manual somehow too any tips or advice is appreciated thanks all
 

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Just picked up sunstar 15 tooth non-damped but I have the damped on the way on back order just in case it's such a pain to get a dealer to do anything around here like they're doing you a favor number one and number two like you're doing something wrong by changing something on the bike they just have bad attitudes I wish I had a dealer like you guys around me LOL so I'm going to do it myself and then I'm going to tighten the chain just the hair cuz it's really loose slapping I watch that bolthole biker guy I've done a few chains in the past but it's been a while I don't know how many you guys watch him he seems pretty good has a good method according to what he says KTM kind of does, but who knows I'm sure I'll be in the manual somehow too any tips or advice is appreciated thanks all
On the bottom side of my pillion seat, (2020 790)(check yours) there's a diagram that shows what the correct chain tension looks like. It matches spot on with the video by BoltHoleBiker.
 

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I was servicing my chain a couple of weeks ago, and came across his YouTube video. I used his method, and it's working fine. Taken some of the slop out, without over tightening it:

Arrghhhhh!! Wish he would correct this video! He is showing the wrong/old method from KTM which leaves the chain too tight and people keep sharing it.

He was advised the comments but ignored it. All you have to do is look at later version of the user manual to see the new method

You measure it 2.5cm past the chain guide
7100
 

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The part that's a bit difficult is getting the top run of the chain taut if it's in neutral, as the manual states. I've done it before as best I could follow KTM's instructions and the dealer said it was like a bow string when they serviced it!
I run with a much slacker chain now with no issues.
 

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I fitted a rapid bike easy this weekend and it has sorted the jerkiness alot all i get now is very slight hesitation but i can cruise a low speeds and highly recommend it, a guy does a fitting video on YouTube helped alot took me about an hour to fit, no engine light just runs how youd expect, i wouldn't change sprockets unless i wanted to change pull off or top speed but im happy with the duke now no crazy engine jerkin
 
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