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Discussion Starter · #1 ·
Recently had a go on a 390 duke and own a 125 duke (2017). Have decided to do a 390 conversion as want to keep my current bike in the family. I am going to document the entire transformation on here as I've seen a few threads but no ones given a step-by-step or any solid info; just speculation. Any issues I encounter I hope to post here, also, as believe some people may make similar mistakes.

I've already sold the engine and loom from my current bike in an attempt to combat the future intense burning in my wallet from 390 ebay parts.

So far I have gathered that I need from a 390:
  1. New shape engine - which I have already sourced costing around £650
  2. Throttle body
  3. Airbox
  4. Exhaust header
  5. Ecu
  6. 390 loom
I am not sure of the next few but ignition coil, power commander and possibly the electronic throttle as heard the 390 model have these but not sure if this is just required if you have an old shape 125. (Pre 2017)
If anyone could confirm this I am making orders over the next few days and spending the money to try this out so you don't have to!

The 125 bike cost me 2400 and I've recouped about £450 selling the engine and loom so lets just say its cost me £2000 for the bike. So far i'm at 2650 so its looking dismal (considering locally 390 dukes are selling for £3000).
 

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Follow this one! Can't wait to see how it works out. May cost a small fortune!

Sent from my VOG-L04 using Tapatalk
 

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Recently had a go on a 390 duke and own a 125 duke (2017). Have decided to do a 390 conversion as want to keep my current bike in the family. I am going to document the entire transformation on here as I've seen a few threads but no ones given a step-by-step or any solid info; just speculation. Any issues I encounter I hope to post here, also, as believe some people may make similar mistakes.

I've already sold the engine and loom from my current bike in an attempt to combat the future intense burning in my wallet from 390 ebay parts.

So far I have gathered that I need from a 390:
  1. New shape engine - which I have already sourced costing around £650
  2. Throttle body
  3. Airbox
  4. Exhaust header
  5. Ecu
  6. 390 loom
I am not sure of the next few but ignition coil, power commander and possibly the electronic throttle as heard the 390 model have these but not sure if this is just required if you have an old shape 125. (Pre 2017)
If anyone could confirm this I am making orders over the next few days and spending the money to try this out so you don't have to!

The 125 bike cost me 2400 and I've recouped about £450 selling the engine and loom so lets just say its cost me £2000 for the bike. So far i'm at 2650 so its looking dismal (considering locally 390 dukes are selling for £3000).
Good effort. Most hot rod projects start out as bonehead ideas, but some work out well enough. If your swap works out well you may help out some other bike owners with similar ideas, whether it succeeds or fails it would instruct other owners how it can be done or show them why it should not be done. Either way your efforts are appreciated. Well done.
 

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Discussion Starter · #4 ·
Update 1, managed to get a hold of someone who has a friend experienced in converting dukes,
They confirmed that all I need is in fact:
  1. ECU
  2. Loom
  3. Throttle body
  4. Right switchgear (electronic throttle)
  5. (not sure about clutch cable so ordered anyway)
They seem to think that the header and airbox are the same which leads me to believe you only need that for a 1st generation duke (<2017) as they are the only ones talked about online.

I ended up paying a total of £400 for these parts
£140 for the ECU
£120 for the throttle body
£110 for the loom
£30 for switch gear

So a conversion kit for a 125 duke would cost around £1000 as of yet...
 

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Cool project. Let's see pictures. Hopefully some video of running bike soon. Keep up the good work
 

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Discussion Starter · #6 ·
Follow this one! Can't wait to see how it works out. May cost a small fortune!

Sent from my VOG-L04 using Tapatalk
hahah, I hope to keep it at least below the price of a decent 390.
of course there's the benefit of forgetting to re register as a 390 for a while.
Good effort. Most hot rod projects start out as bonehead ideas, but some work out well enough. If your swap works out well you may help out some other bike owners with similar ideas, whether it succeeds or fails it would instruct other owners how it can be done or show them why it should not be done. Either way your efforts are appreciated. Well done.
Yes i've seen a few people who've just said they want to do it but no ones given it a go and documented it - from what I can see.
Cool project. Let's see pictures. Hopefully some video of running bike soon. Keep up the good work
The conversion parts are coming in 2 days so hopefully videos in 3 days ;) being optimistic
 

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Discussion Starter · #7 ·
Apologies for the late update, weather got in the way. Here is where I am at so far, I will try and recall from memory the things that weren't straight forward and outline the things that were just for reference.

Parts arrived in good time and today I got the chance to start work tearing down the 125. I started by removing the tank which required the ignition cover to be removed before I could take two bolts attached to the tank side fairings - the only part which caused some issues as was very tight (just pops out with a decent amount of force).
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Once the tank was lifted, remove the fuel lines attached to the fuel filter and electronics on underside of tank.
Now to remove the airbox, you must remove the two retainer bars either side and the single bar across the box. The side bars have two bolts which you have to access from inside the frame subframe rather than from the exterior like the rest (pictured) which were quite awkward as I could only turn about 45 degrees at a time.
Loosen the clamp on the throttle body and then slide the box backwards to dismount from throttle body and then forwards again in order to free from the airbox vent. Be careful not to snag any cables, then remove the airbox sensor from the right side of the box - and its housing.
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Now to remove the throttle body its self, disconnect all connected cables and then loosen the clamp to the intake. Remove the throttle cable and then slide off body. I stuffed some bubble wrap inside intake to prevent aliens entering the top end.
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Next the radiator, which I drained from the screw on bottom of pump and then some awkward positioned bolts under plastics and by manifold. I next attempted to remove my manifold but was stuck on tight, wacked with a hammer, WD-40'd and attempted to pry off but to no avail so continued with it still in the engine. I did have to remove all the hosing for the coolant system as a result as otherwise would be caught when I dropped the engine.
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To drop the engine, first removed all cables and began loosening bolts on engine guards, attached a ratchet strap and removed all engine bolts. slowly released ratchet and lowered the engine to the ground.

I started with the loom by changing over fuse box area etc but got too dark. Will update in a few days.
 

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Awesome build. Good work
 

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Discussion Starter · #10 ·
A lot has happened...
Had the 390 engine lifted when the front two drop down black mounts did not match the engine mounts. At first i thought the engine was the wrong size but after some research the drop down supports are different on the 125/200 duke than to the 250/390 duke, £25 each from ktm.
Also the radiator hose which goes from the pump on the engine up to the bottom of the radiator and also the stretch from that to the splitter across the engine to the manifold side is also different and each cost about £5 from ktm.
There is also a sensor on the top of the engine which is not there on the 125 which plugs into the head of the engine and a breather hose located by the alternator.
The engine its self would not start and I created another post with some videos KTM duke 390 starting issues...
turns out the compression was very low (something I somehow didn't check when buying the engine, would've saved £650...
Today I picked up a brand new 2019 RC390 engine which I hope I can put into the 390. It had a bracket at the bottom (will show photos tomorrow) which i removed and then switched over all radiator and other bits.
Tomorrow I will top up all fluids and hopefully get a first start and a ride video.
More detail tomorrow.
 

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Discussion Starter · #12 ·
Lost some motivation after this second engine now has a suspected second gear tooth snapped on the gear cog. I've been out for a ride on the bike now as all together however second gear under any load will make a horrible sound. Every other gear is perfect and the bike runs smoothly its just second gear. I will be stripping the first engine for parts and so will see if the gear from that is usable in the new engine. If so, hopefully just a few youtube videos away from a lovely running conversion.
I'm sure once I split casings the old engine and gain some motivation i will update all the work I have done but for now i cannot bring myself as the thought of having to buy another engine is making me very happy - not.
 

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Well good on you for your accomplishments thus far. Unfortunate for you to find a sick transmission, but $hit happens. You would expect bikes that size would get well thrashed in second gear and probably the reason yours is toast. Ah well. So much for hard luck. We all get a share of $hit in our hat from time and again. Your persistance and good work has helped other folks here with your hard earned knowledge. Thanks for your good efforts and be sure to check back often with pictures and videos of your project. Best of luck to you
 

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Discussion Starter · #14 ·
Bought a new 2019 engine from a crashed bike and that ended up having no second gear, since then I’ve completely broken the engine, split the crank cases, replaced the gearbox and all components related as found no damage except some dirt and grit and have sold the bike. I ended up getting £4350 for the bike.
I will maybe soon upload all the photos or maybe even have the chance to actually tear down a 390 on camera and record it all properly.
 

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hola finalmente no cambiaste el motor porque no pudiste poner el motor en el chasis de la 125 o porque los motores que compraste no funcionaban bien, también quiero cambiar el motor y no sé si se puede. ..
 
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