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Discussion Starter · #1 ·
Duke 390 Scrambler build in action today. After my first off road ride a few weeks ago which was on some pretty mild roads I realised the front springs had far too much sag and bottomed way too easily, even on very small hits. The standard springs are very soft dual rate with 0.62kg/mm at the firm end and were sitting almost halfway through their stroke with me just sitting on the bike. I had a gamble and bought 0.75kg/mm linear YSS springs for the RC390 (they come in 0.75, 0.8 and 0.85) and they were spot on. These gave me 40mm rider sag leaving me with 110mm of additional travel. I hit some much more aggressive tracks to really test out it's potential and it was awesome. The front didn't bottom out once, but also used every bit of available travel with less than 5mm unused. The rear (R6 shock) was fine as it was last ride with no bottoming at all.

I also got to test the Rapid Bike Easy which was perfect for this kind of riding as it gives the bike much more usable power under 4krpm where it used to rattle and vibrate. This combined with 1 tooth down on the front sprocket made hill climbs at lower rpm much easier. I'll fit some lower pegs to make the standing riding position a bit better since the bike is quite a bit higher off the ground now but that's really all that's left to improve.

Yeah I know, I could have bought a 390 Adventure, but this was less than 1/2 the price and isn't anywhere near as ugly. Besides, I said I wouldn't get an adventure bike until after I turn 40 馃槀

2015 Duke 390.
TKC80 tyres.
EBay crash bars.
EBay skid plate.
Ebay hand guards.
Ebay levers.
EBay radiator guard.
MX bars.
Extended clutch cable.
Rapid Bike Easy.
Longer side stand.
R6 shock.
YSS 0.75 linear fork springs.
YSS height adjuster caps.
14t front sprocket.
Enduro foot pegs.

51676


51677
 

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So I live in an area where I have access to fire roads and trails and have taken the Duke on road tires. I'm looking to upgrade the road tires when these wear out. I'm very mellow off road but really would like to figure out how to stand on the bike while off road. Would raising the handlebars work? I've been looking at some risers but not sure how much I need to raise them. Adjusting the foot peg position seems non trivial. Any advice?
 

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Discussion Starter · #5 ·
So I live in an area where I have access to fire roads and trails and have taken the Duke on road tires. I'm looking to upgrade the road tires when these wear out. I'm very mellow off road but really would like to figure out how to stand on the bike while off road. Would raising the handlebars work? I've been looking at some risers but not sure how much I need to raise them. Adjusting the foot peg position seems non trivial. Any advice?
The bike doesn't have a great standing position to begin with because it's quite cramped. I have slightly higher/wider MX bars fitted but it's tight work getting the throttle cable and brake line to any further than what I have. The clutch cable was the tighest but I installed a slightly longer clutch cable which was very easy to do and was only $15AUD on eBay. What really helped was the firmer springs up front because that in itself greatly reduces the amount of sagging the front end has, at least on the Gen 1, so you're gaining 30-40mm by doing that. Obviously that's not why I did the springs, but it was definitely a bonus. My next step will be lower pegs. With the R6 shock at the back and fork springs+YSS height adjuster caps at the front my bike is sitting much taller than standard. I needed to install a longer side stand as it could no longer balance. This is good though, as I have gained significant ground clearance (200mm overall). So lower pegs makes sense now that the whole bike is higher off the ground. This should also help with the standing position quite a lot. There are 40mm lowered pegs available on eBay which I'm going to purchase so the combination of taller bars, a less saggy front end, and lower foot pegs should be enough to make occasionally standing less of an issue.
 

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Duke 390 Scrambler build in action today. After my first off road ride a few weeks ago which was on some pretty mild roads I realised the front springs had far too much sag and bottomed way too easily, even on very small hits. The standard springs are very soft dual rate with 0.62kg/mm at the firm end and were sitting almost halfway through their stroke with me just sitting on the bike. I had a gamble and bought 0.75kg/mm linear YSS springs for the RC390 (they come in 0.75, 0.8 and 0.85) and they were spot on. These gave me 40mm rider sag leaving me with 110mm of additional travel. I hit some much more aggressive tracks to really test out it's potential and it was awesome. The front didn't bottom out once, but also used every bit of available travel with less than 5mm unused. The rear (R6 shock) was fine as it was last ride with no bottoming at all.

I also got to test the Rapid Bike Easy which was perfect for this kind of riding as it gives the bike much more usable power under 4krpm where it used to rattle and vibrate. This combined with 1 tooth down on the front sprocket made hill climbs at lower rpm much easier. I'll fit some lower pegs to make the standing riding position a bit better since the bike is quite a bit higher off the ground now but that's really all that's left to improve.

Yeah I know, I could have bought a 390 Adventure, but this was less than 1/2 the price and isn't anywhere near as ugly. Besides, I said I wouldn't get an adventure bike until after I turn 40 馃槀

2015 Duke 390.
TKC80 tyres.
EBay crash bars.
EBay skid plate.
Ebay hand guards.
Ebay levers.
EBay radiator guard.
MX bars.
Extended clutch cable.
Rapid Bike Easy.
Longer side stand.
R6 shock.
YSS 0.75 linear fork springs.
YSS height adjuster caps.
14t front sprocket.
Enduro foot pegs.

View attachment 51676

View attachment 51677
Do you happen to have the part numbers for the yss parts?
 

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Discussion Starter · #7 ·
LR365A075S345 for the fork springs. Keep in mind they're actually listed for the RC390 so they come in 7.5N (lighter), 8.0N (standard) and 8.5N (heavier). The Duke forks have more travel and so use a lighter spring standard which is 0.62N, so the 0.75N are quite a bit firmer when used in the Duke. The RC390 springs are also slightly longer but you just toss the spacer which is in the Duke forks.

Not sure on the fork height adjuster part number but in retrospect they're not really needed as you pay quite a bit for a very small amount of extra height (not extra travel).
 

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LR365A075S345 for the fork springs. Keep in mind they're actually listed for the RC390 so they come in 7.5N (lighter), 8.0N (standard) and 8.5N (heavier). The Duke forks have more travel and so use a lighter spring standard which is 0.62N, so the 0.75N are quite a bit firmer when used in the Duke. The RC390 springs are also slightly longer but you just toss the spacer which is in the Duke forks.

Not sure on the fork height adjuster part number but in retrospect they're not really needed as you pay quite a bit for a very small amount of extra height (not extra travel).
Thanks
 

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Duke 390 Scrambler build in action today. After my first off road ride a few weeks ago which was on some pretty mild roads I realised the front springs had far too much sag and bottomed way too easily, even on very small hits. The standard springs are very soft dual rate with 0.62kg/mm at the firm end and were sitting almost halfway through their stroke with me just sitting on the bike. I had a gamble and bought 0.75kg/mm linear YSS springs for the RC390 (they come in 0.75, 0.8 and 0.85) and they were spot on. These gave me 40mm rider sag leaving me with 110mm of additional travel. I hit some much more aggressive tracks to really test out it's potential and it was awesome. The front didn't bottom out once, but also used every bit of available travel with less than 5mm unused. The rear (R6 shock) was fine as it was last ride with no bottoming at all.

I also got to test the Rapid Bike Easy which was perfect for this kind of riding as it gives the bike much more usable power under 4krpm where it used to rattle and vibrate. This combined with 1 tooth down on the front sprocket made hill climbs at lower rpm much easier. I'll fit some lower pegs to make the standing riding position a bit better since the bike is quite a bit higher off the ground now but that's really all that's left to improve.

Yeah I know, I could have bought a 390 Adventure, but this was less than 1/2 the price and isn't anywhere near as ugly. Besides, I said I wouldn't get an adventure bike until after I turn 40 馃槀

2015 Duke 390.
TKC80 tyres.
EBay crash bars.
EBay skid plate.
Ebay hand guards.
Ebay levers.
EBay radiator guard.
MX bars.
Extended clutch cable.
Rapid Bike Easy.
Longer side stand.
R6 shock.
YSS 0.75 linear fork springs.
YSS height adjuster caps.
14t front sprocket.
Enduro foot pegs.

View attachment 51676

View attachment 51677
Great stuff! :D Love it! And also love the idea of the spoked wheels! I have dinted mine a couple of occassions... :(
Question for you - have you changed or done anything to the exhaust at all?
 

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Looks Great, off road mine all the time. Watch Those wheels I understand They break easy, I got a set off the Husqvarna
Hi Jack, can you tell me what model Husqvana they're from? And did you also have to change the hubs or disks / anything at all or was it a straight fit?

This is my Lawnmower fully laden on a trip....
51814
 

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Discussion Starter · #11 ·
Great stuff! :D Love it! And also love the idea of the spoked wheels! I have dinted mine a couple of occassions... :(
Question for you - have you changed or done anything to the exhaust at all?
No, I left the stock exhaust exactly as it because it sits so nicely out of the way. This is the first bike I've ever owned that I haven't touched the exhaust on. I'm lucky enough to not have damaged the stock wheels..... yet..... Luckily second hand ones are pretty cheap. The wheels of the Svartpilen 401, not so cheap.
 

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ckily second hand ones are pretty cheap. The wheels of the Svartpilen 401,
Thanks for the info; yes that is part why i left my exhaust intact - until the last incident, was thinking if i could find one that it is just as 'out the way' as the stock I would change it. And make it lighter in the same process :)

I've looked at getting the hubs redone and relaced on the stock wheels but it's just too hard. And costly, from what I've seen it's about the same cost getting brand new ones made and laced with spokes, than it is to buy they out right from the Svartpilen 401 ... however what I wasn't sure about was the ins and outs of the ABS/brake ring etc.
 

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Good suspension upgrade and good tyres.
Bash plate but yes, the ground clearance is not comparable with enduro or off-road bikes nor is the suspension travel.
Standing on the pegs (I have Adv pegs) is also not too easy without handlebar risers BUT I have been riding the dirt tracks (such as the Ho-Chi-Min trail(s) since 2015 so I think the Duke is great for off-road.


Problem with duke is that the suspension is hard for off road riding so you have to be at stand up position constantly...

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I鈥檝e read a few reports that say with a few mods (Tyres, suspension, handlebar risers etc) the 390 actually makes a great 鈥楢dventure鈥 type bike.

The biggest potential issue / weak link supposedly being the cast mag wheels 馃し鈥嶁檪锔
 

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It is indeed.
You'd expect the rims to be a potential issue but I have pounded through some nasty potholes and ridden over rocky terrain and must say that they have held up pretty nice till now.
One of the things that you must change is the engine cowl and replace this with a bash plate as that is one of the first things that will get damaged.

I鈥檝e read a few reports that say with a few mods (Tyres, suspension, handlebar risers etc) the 390 actually makes a great 鈥楢dventure鈥 type bike.

The biggest potential issue / weak link supposedly being the cast mag wheels 馃し鈥嶁檪锔
 
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