Change Front Sprocket KTM Duke 390 125 200 250

[@shawnh4528]

I always felt like working on the bike may mess up certain things so I'm always afraid about it but your videos in explaining about everything helps me to approach the bike with confidence that there are certain things that could be done by ourselves. Thank you soo much for your videos. Love your work from India (South) and may be visit India someday. ✌️

[@MotoMirius]

Thanks. Just that touch of confidence and experience is all that you need. Take it one step at a time and soon you will be confident enough to do nearly anything on the bike.

[@shawnh4528]

@@MotoMirius thank you so much for these wonderful words, they're are so motivational. I'd remember these words which would be helpful for me. Thank you so much, I'm glad and blessed to find your work here at KZbin so that I'll be able better understand my bike. 😇

[@Taruup]

I have KTM 390 adventure. I am a total noob when comes to working on my bike. But your videos are so well explained and so precis that even I managed to change sprocket and chain all on my own after watching your videos. And that's says a lot. So thank u very much sir. 😊

[@MotoMirius]

Thank you and well done with your installation!

[@springy-2112]

Always concise David , another quality video . Good to see you pass on the knowledge . So calm , no drama. Peace and love brother 👍🏻☮❤

[@MotoMirius]

Thanks Springy. Just dug out the silencer for you!

[@springy-2112]

@@MotoMirius Cheers David no rush mate ..👍🏻☮❤

[@MotoMirius]

No rush, I wanted to make sure it was where I thought it was 😂

[@manugrend]

Just found your channel and have watched at least three vidoes in a row! So well done and explained, you really help us "novice" ppl become more comfortable with doing maintenance on our bikes. I've been thinking about chainging the chain and sprockets myself, but I'm stuck on the rivetting of the chain part, I don't have the tool for it. I noticed on your bike you're using the "clip on" chain link. Is this because you use the motorcycle only for stunts or would this type of link be suitable for normal road use? If not what tool method would you suggest for linking the chain. Txs!

[@MotoMirius]

Thanks, much appreciated. Typically I would use a riveted link for chain but with small capacity bikes you can get away with the clip link - I wouldn't outright recommend it with the 390 because it does have a bit more power, I use it because I do change sprockets etc for videos and it avoids buying new rivet links all the time which don't match the wear on the chain. I would recommend that you invest in the rivet tool - it is a once in a lifetime purchase and you will recover your money the first time you don't pay someone to fit the chai. The tool you need is - www.didchain.com/products/km500r-chain-tool Don't buy a copy or anything else. For a video on how to use the tool - kzbin.info/www/bejne/hH-xqKOEjpyWlZIsi=EXkxKVAOZV6LAjsJ - I must make a video on using this tool properly too!

[@prashantambhore5775]

Hi David hope you’re doing great. I have two questions please answer. 1) On my 125Duke should i drop one tooth or increase the teeth on rear sprocket? (I am looking for faster initial acceleration and wouldn’t mind sacrificing top speed as i rarely hit highways and mainly have spins around the town) 2) I am inclined towards dropping one tooth on front (easier and cheaper) so would it work with the stock rear sprocket and stock chain?

[@MotoMirius]

Hi, I'm good thanks and hope you are too. Sounds like you have the right idea and yes I would agree with 2 and there would be no issues with stock sprocket and chain. But, the 125 already runs a 14 on the front if I recall correctly and a 13 creates a much tighter turn for the chain which may increase wear. You would also be advised to keep a close eye on the rubber chain slider at the engine end of the swinging arm because with a small front sprocket the the chain will wear it out quicker and can then cut into the swinging arm.

[@prashantambhore5775]

@@MotoMirius thanks for the valuable input. One more question if i go ahead with the smaller front sprocket and it somehow happen to wear out swing arm rubber chain slider would it be replaceable or i am in a trouble? (I am totally noob)

[@MotoMirius]

The slider is replaceable and not expensive in itself. But you do need to keep an eye on it otherwise you could need a new swinging arm. Unless you have a new chain and sprocket fitted on the bike, then long term you would be better with say a 45 tooth sprocket on the back.@@prashantambhore5775

[@prashantambhore5775]

@@MotoMirius ahh thanks for helping out.

[@ricardopinto1765]

Hello Mirius once again... What are the gain's on this change? More specific do you get more torque? Better acellaration if needed 😅. Sorry to asked 😅😮

[@MotoMirius]

Well it depends what change you make. The effect is the same as changing the rear sprocket (but remember that the effect is reversed - so a smaller front sprocket is the same as a larger rear). Generally I don't use smaller front sprocket - but the 125 has a smaller so 1 tooth down is probably OK. Risk of a smaller sprocket is that it will increase wear on the rubber slider and risk cutting into the swinging arm. So, there is no simple answer to your question because we are looking at a small capacity bike. Typically a larger rear/ smaller front will increase torque sightly which can increase acceleration and sometimes top speed, but can also increase fuel consumption. In theory a smaller rear sprocket will increase top speed but won't always - much depends on for example how much the rider weighs.

[@Kuper133]

Привет, Дэвид! Не могу узнать какие мне нужны звезды на ктм дьюк 250 2016 года. Я покупал мотоцикл не новым и не уверен что стоят родные звезды. Сейчас передняя звезда стоит 13 зубьев и задняя 52.Я не хочу эксперементировать. Хочу поменять и поставить родные звезды. Не подскажишь какие родные звезды нужно покупать?

[@pedroplatzerdamotta]

Nice! Could you please record an onboarding video to show us how the bike handles after this change?

[@MotoMirius]

Thanks. I will be doing something. Turns out it's quite a big change - bike is really geared down.

[@KaRim-es9xx]

Hi David, thanks for all your tutorial videos !!!! On the Duke 125cc have you ever tried the 15 front sprocket,. I tried the 13, but didn’t like it.

[@MotoMirius]

I've not tried the 13. I'm not so sure if its not too small given the clearance on the swinging arm. As to whether it does what you want, some testing has shown that the 48 rear or 13 front can improve acceleration and top speed on the 125, but it's always about what works for you - I tend not to use gearing most people use on these because it's not my only bike so I'm not looking for top speed or long distances on the motorway. I suspect a 15 on the 125 will kill the acceleration and may reduce top speed because you may only be able to get into top gear going downhill - but there is only one way to find out!

[@tinks43]

Well explained mate, simple stuff. I hope it has done as you intended? 👍🏻

[@MotoMirius]

Thanks Dave. Well it's now no faster than a 125, so it's done something! I need to go out and play.

[@juanposada9319]

So David, if going from 15 to 14, will this make the bike accelerate faster and lose a bit of top end?

[@MotoMirius]

It is the equivalent of putting a bigger sprocket on the back so yes. But, although it will accelerate faster, you will go through the gears quicker, and gear changing interrupts acceleration, so it depends exactly how you intend using it. Testing on the RC by Grey Area KTM showed fastest 0 - 60 was with stock gearing.

[@nathanfenech9018]

Nice job mate. I had a question about my 2018 duke 390 . It turns off (stalls, ignition stays on), when it turns on on cold start. It seems to happen less often when it's warmed up. Not sure if it has anything to do with the debaffle I did. I'm asking as I'll be getting an SC project soon, and was worrying it might make this worse. Thanks in advance!

[@MotoMirius]

Thanks. Possibly related but sometimes can happen with cold start (when it's cold), assuming of course that you are not touching the throttle too soon as that will always kill it. If you are getting an SC then I'm assuming you already have or will have a piggyback on the way which will cure any issues you might have with the changes needed for fuelling. Skäl David

[@TheJWC56RSA]

Nice job - as always! Regards!

[@MotoMirius]

Thanks. Always appreciated!

[@Brownkid422]

So am i reading the comments correctly: with a 14 tooth front AND a 48 tooth rear on at the same time you top out around 75 mph? How is the 14/48 for stunting vs 15/48?

[@MotoMirius]

Depends on the sort of stunting you are aiming to do - if you are looking at more technical close quarter stunts then speed is not relevant - much like trials riding - you never ride a trials bike at 75, so who cares? 15 48 is a good compromise for general riding and stunts, doesn't have too much impact on top speed but is more responsive to the throttle than stock 15 45.

[@Funny_as_Duck]

What is your recommendation on new tires? I want grip more than longevity. But if there’s best of both worlds that would be nice. People say the Michelin street pilots slip and I don’t want to ever slip lol

[@MotoMirius]

For every tyre there are people who claim it's the best tyre ever made and people who claim it's the worst tyre ever made. Internet rumours are also not to be trusted no matter how often you hear people repeat them. I heard many times for example that the stock Metzeler were terrible and slipped yet mine never did. One thing to bear in mind is that this is a bike often ridden by novice riders who for example don't check their tyre pressures, attribute their own poor riding skills to faults in the bike or fit tyres not recommended for the bike. My recommendation is to go for a reputable brand and go with what that brand recommends fits this bike - most have websites not something you've seen somewhere on the internet - Michelin for example recommend the Pilot Power, a sports tyre not the Street Pilot. Most of the tyres made that fit this bike are grip oriented rather than longevity as most of the wheels this size are found on sports type bikes.

[@cavitecheckpoint]

David i have a question, is it possible to repair a grounded gear shift indicator without replacing it? Whens the next vid comming?😁

[@MotoMirius]

It depends exactly what needs repair. Next vid is coming soon - next week I hope - I'm starting again on current video. Thanks!

[@Prashant_rw_]

Hey david, i want to change my stock chain with the orange one, can i only change the chain or should change the whole sprocket

[@MotoMirius]

Hi, if the sprockets are new then yes, it's fine. If the sprockets are worn then it will accelerate wear on the chain, so it depends on the condition of the sprockets.

[@Prashant_rw_]

@@MotoMirius i have ridden around 6,000km is it okay?

[@MotoMirius]

Depends how well its been looked after - could be like new or it could be worn out. You need to look at the sprocket teeth - it helps to compare to a new sprocket.@@Prashant_rw_

[@snopdogg92]

Can we replace 14 teeth front sprocket, the stock sprocket is 15 teeth, will be there any effect by doing this.

[@MotoMirius]

Yes, you can and I have. Of course there will be an effect - you have changed the gearing. It is the same as going to a 48 tooth rear.

[@superbyke125]

Hi is it normal to have a bit of play on the front sprocket?

[@MotoMirius]

Yes, it is.

[@125W4life]

I got rubber spacers with my new sprocket, where do they go?

[@MotoMirius]

Depends what they look like?

[@125W4life]

@@MotoMirius It was for the chainlink xd

[@robmcgregor8759]

Have do you know how many links the ktm duke 125 2022 has? Thank you

[@ralphjansen8715]

I think it was 111 links

[@danielmtz9488]

Can use for a Duke 250 an sprocket kit for Duke 390?

[@MotoMirius]

I've not tried it as they don't sell the 250 here but yes, it should fit - though I can make no guarantees

[@650ali3]

With the 14 tooth on the front what sort of top end did you gain please mate

[@MotoMirius]

I have a 48 on the back so top end is now about 75mph. Great for stunting not so great for top speed. Smaller on the front is like bigger on the back.

[@650ali3]

@@MotoMirius thank very much this is for my mate on his ktm 125

[@MotoMirius]

@@650ali3 125 already have a 14 on the front. They do benefit from improved gearing but while i've seen a 13 for sale I'm not sure if it's a good idea because you may get chain rub on the swinging arm. With a 125 a 48 rear has been shown to improve acceleration and top end

[@JeeGaa]

Does 16 teeth sprocket fits 125? Or 15 is max for 125?

[@MotoMirius]

125 uses different front sprockets from 390 but you can get different sizes - they can be hard to find in stock - they are made in small batches, so it's hard to say if you can find one. If you can find a 16 then you may need to remove the chainguard.

[@lankzz9093]

Any chance of showing us an engine removal/install??

[@MotoMirius]

Engine removal is upcoming. I'm waiting for parts and to clear out some existing projects which are taking up space.

[@lankzz9093]

@@MotoMirius great. Would you be showing us valve clearance check? I’m currently waiting to do mine

[@MotoMirius]

@@lankzz9093 I will be showing it as part of the engine removal (because easier to film) but first I need to finish fixing some bikes as I currently have three bikes apart.

[@saipratheek5499]

💪

[@MotoMirius]

Thanks

[@qilqilqil8863]

Anyone knows the nut sizes for the sprocket cover?

[@MotoMirius]

Buy a set of small sockets, you might get them with a spanner. Don't waste money trying to buy just one socket, it will always be more expensive. If you need to know the size just use a ruler - these are all metric.

[@kodyyouso264]

I’m running a 2021 KTM Duke 390 myself…although I’m having an extremely difficult time locating a 14T front or 48T rear sprocket for this bike here in the US. Any chance you could point me in the right direction so I can get a new set of sprockets ordered? Either looking to run 15/48 or 14/45. I’ve only got about 750 miles on the bike but I’d prefer to replace both sprockets and chain to give a bit more low end torque. Thanks in advance and great videos truly!

[@MotoMirius]

Try not searching for a 2021 as most manufacturers probably haven’t had chance to check if the new model runs the same chainset. But the BS6 was actually launched in some markets in 2020.

[@madsoothsayer]

I'm looking for a bit more punch through the gears. Do you recommend the 14 front while keeping the stock rear sprocket. I mostly ride twisty canyon roads... Thanks!

[@MotoMirius]

I would say give it a go and see, I think it should work for you.

[@statuskannada87]

Front sporket size please

[@MotoMirius]

For which bike?

[@statuskannada87]

@@MotoMirius duke 200

[@statuskannada87]

2019 model

[@MotoMirius]

@@statuskannada87 www.jtsprockets.com/catalogue/part/JTF1903/

[@faiyazrain786]

Will it be a good idea if i change stock 14t front sprocket to 15 on duke 250...will it affect acceleration??

[@MotoMirius]

It depends what your idea is. Yes, it will affect acceleration, but there are no simple answers because it depends what you are looking to do. With a small bike you can't believe the gearing charts you see online - they assume unlimited power. A 15 may make a 250 slower because it lacks the torque to overcome wind resistance at high speed. It will allow you to cruise at lower revs but may mean changing gear earlier on steep hills. There is no one simple answer - the best gearing depends how and where you ride, and the only way to discover this is to try it.

[@daveh8263]

Is it normal for there to be be a little play in front sprocket?

[@MotoMirius]

Depends what you mean by a little play?

[@daveh8263]

@@MotoMirius my front sprocket seems to wiggle “in and out” by 1 or 2mm

[@MotoMirius]

@@daveh8263 The clamp will hold it tight on the shaft. Is the shaft also moving? There will always be some clearance in the gearbox, but 2mm sounds excessive.

[@ezioauditore2376]

Does it power wheelie now?

[@MotoMirius]

390 power wheelies out of the box, but yes, more so now - but my aim is not to do power wheelies!

[@MassimoTava]

Anyone made changes in order to lower top gear rev at 80-90mph? Not sure if it ruins the feel of the bike

[@TheJWC56RSA]

I fitted a 150 rear tire - it is a bit higher (larger diameter) than stock and went down one tooth at the rear... The 390 is now more suited to riding higher speeds on the national roads.

[@MotoMirius]

16 tooth on the front is an easy way to lower top gear rev. Not my thing, but depends how you use the bike so if it works for you then that's all that matters!