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Discussion Starter · #1 ·
Lets go displacement hunting today. Usually we compare the Duke 390 with similar displaced CBR300s and Ninjettes always to come to the same conclusion, the Duke will outperform and out handle both of the quarter liter entry levels handily however the Duke 390 is constantly tripped up on price.

So I started thinking about it and figured the Duke 390 is such a raucous performer lets give him a shot in the bigs in a little showdown with the half liter Honda CB500F...



I'm going to avoid pricing discussions for now because we're quickly becoming an international forum and pricing is NEVER consistent across markets.




Right off the bat you tell which bike has more confidence. The Duke 390 exposes its gorgeous orange frame while the CB500F still has beach fright and covers all its sexy bits up with plastic casing. The headlight is ugly and the can is atrocious. Duke ALL DAY.

However bikes are much more than visuals, does the 390 have the substance to back up the style?



Green: Honda CB500F
Red: KTM Duke 390

The torque curves show a noticeable dominance for the CB500F which is predictible considering its 471cc's to the Dukes 373cc's. Towards the top end of the power scale the Duke 390 does edge out advantages.

Power and torque readings to the crankshaft (CE95 standard / 1)

Honda CB500F (green curves): 47.1 hp at 7866 rev / min, 4.8 kgm at 6234 rpm / min
KTM Duke 390 (red curves): 46.9 hp at 6980 rev / min, 4.4 kgm at 5750 rev / min

Power and torque returned to the wheel

Honda CB500F (green curves): 42.9 hp at 7866 rev / min, 4.2 kgm at 6234 rpm / min
KTM Duke 390 (red curves): 42.8 hp at 6980 rev / min, 3.8 kgm at 5750 rev / min

The Duke revs much higher than the CB500F which allows for beautiful pace through back roads or highway cruising however once you get north of 125 KM/H the Duke starts to show its single characteristics, heavy vibrations indicate the Duke 390 does not like that range for prolonged periods.

Honda CB500F: 425 lbs
KTM Duke 390: 334 lbs

91 lbs delta in the Duke 390s favor is quite noticeable through the bendy bits and in the power delivery.

9.04 lbs/HP for the CB500F
8.35 lbs/HP for the Duke 390




It all comes down to usage and preference. the Honda was designed to tour the KTM could tour. Honda recommends a visit to the shop every 12,000 km, valve clearance adjusted every 24 000 km. KTM recommends a shop visit every 7500 km, with a check valve clearance every 15,000 km.


 

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So based on the data above....at 6,980rpm is where 390's get full 42.8hp? Is that how I understood it?

So we dont have to pass 7,000rpm? We upshift when we see it hit almost 7,000? That correct? Cos it will be piontless to make it hit more than that as the power curve just heads downward after 6,980rpm?
 

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however once you get north of 125 KM/H the Duke starts to show its single characteristics, heavy vibrations indicate the Duke 390 does not like that range for prolonged periods.
SO basically you shouldn't go over 125 km/h with the Duke 390? Or at least it won;t be comfortable at that speed? That's a little disappointing to know.
 

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I cant agree with that, Ive had it just off the 10,000rpm mark and it was still pulling. Ive also had it to 137km/h without an issue and the wind buffering was minimal. Im pretty impressed with this bike......insane cornering ability. Am currently doing up a thoughts piece on it and will post when Im done.
 

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i set my RPM 1 on 9K and RPM 2 at 10K .. usually i'll rev till the last bit of juice before i change gear ... i'll try to note down my usual behavior .. once the sun came out and play ...:(

anyway a 7K .. it's abit toooo early to shift ... please continue throttling ... the duke says it ain't enough ...:D :D :D
 

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i set my RPM 1 on 9K and RPM 2 at 10K .. usually i'll rev till the last bit of juice before i change gear ... i'll try to note down my usual behavior .. once the sun came out and play ...:(

anyway a 7K .. it's abit toooo early to shift ... please continue throttling ... the duke says it ain't enough ...:D :D :D

But Dyno's dont lie....Based on the data above, It does make maximum HP close to 43 at 6,980rpm...that's what the Dyno says...so going over that, you notice the line on the graph simply tails off at higher RPM...
 

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Discussion Starter · #10 ·
can you guys chime in on power delivery? They dyno graph shows the 390 has a snaking power curve vs the Hondas linear ascension. Is that something noticeable on the street?
 

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Its kinda like that, the bike gives you a chance to back off if you get ham fisted
Easiest way to explain it:
Rider - OK bike lets go
Bike - Are you sure?
Rider - Yes
Bike - Are you really sure??
Rider - YES!!
Bike - OK THEN!! HOOOOLD ON!!!!!!

The bike has a split personality, it can be super sedate but if you want it to it can also have a very bad attitude......instant hoonigan :D
Seasoned riders will be looking for a map/torque curve change but new riders to the road will be thankful for its fuelling.
If anyone ever asks whats the right first bike for them I will say the Duke without hesitation, the balance and cornering this bike has is pretty impressive and its certainly got the rider in mind every moment.
 

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But Dyno's dont lie....Based on the data above, It does make maximum HP close to 43 at 6,980rpm...that's what the Dyno says...so going over that, you notice the line on the graph simply tails off at higher RPM...
The maths seems to be wrong here. According to my calculations the gearing is for about 145 kph at 9500 rpm and KTM quote peak power at that. I can't believe KTM could be so far out.

I don't know if the curve was done in top gear though.
 

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The maths seems to be wrong here. According to my calculations the gearing is for about 145 kph at 9500 rpm and KTM quote peak power at that. I can't believe KTM could be so far out.

I don't know if the curve was done in top gear though.
Finally!!!! Ding Ding Ding, Winner Winner Chicken Dinner!!!! Give this poster a cookie. :eek:

I get the same speed on my dash, havent had it much past 145 but by 140 its screaming "help me help me help me". I cant explain why people report 180 etc but I just dont see it myself.
 

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Discussion Starter · #15 ·
Finally!!!! Ding Ding Ding, Winner Winner Chicken Dinner!!!! Give this poster a cookie. :eek:

I get the same speed on my dash, havent had it much past 145 but by 140 its screaming "help me help me help me". I cant explain why people report 180 etc but I just dont see it myself.
unless the 180 crowd has done sprocket work?
 

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Or the motor registry body adds extra k's in the computer? In Aus our speedo gauges are roughly 6 to 10 kilometers slower than it shows. So if im doing 100km/h Im really doing 92km/h, its their way of triming some speed of without people really knowing it.
40k does seem a bit excessive but Ive read reports of other bike manufacturers in countries being way out. GPS and photo I guess :D
 

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The maths seems to be wrong here. According to my calculations the gearing is for about 145 kph at 9500 rpm and KTM quote peak power at that. I can't believe KTM could be so far out.

I don't know if the curve was done in top gear though.
Sorry I have to correct that. I took the front sprocket size from the sales information and it turns out this may be wrong. If a 15 tooth front sprocket is fitted ( rather than a 14 tooth) it would be around 160 kph at 9500 rpm.

Next task is to do some constant speed runs with a GPS system recording them and use that to check speedo calibration. I'm going to need a few more miles on the clock first though.
 

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As one member has already pointed out, there looks to be some confusion on the dyno graph.


Based on the dyno test graph for KTM Duke 390,
42.8 hp at 6980 RPM with speed=145kmph
3.8 kgm at 5750 RPM with speed=120kmph


With stock settings and in the top most gear, this is the data for speed per 1000 RPM - 17 kmph per 1000 RPM. Going by that data, 6980 RPM should result in the speed close to 119 kmph, but the graph indicates a different speed (145 kmph). Similarly, 5750 RPM should result in 98 kmph, but the graph indicates the speed to be around 120 kmph.


Either the 390 being tested is not having the stock settings (different sprockets, etc..) or there is some issue with the testing itself. We need to get some clarity on the dyno graph. If we go by the graph, the speed per 1000 RPM works out to be around 20 kmph per 1000 RPM and this cannot happen on stock settings.


I am also surprised by the comment saying that 390 will struggle beyond 140 kmph. I have seen many videos where 390 reaches 160 kmph with no fuss.
 
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