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Discussion Starter #1 (Edited)
At my recent trackie, the 2008 DukeR which has been remapped, but is identical to my set up otherwise, cleanly pulled past me on the straight. Don't worry, I have a therapist.

Also, his dyno run gave him no more than 1/2 a hp over me.

He is a smaller and lighter rider than I am, but that shouldn't alter terminal speed. He might be more aerodynamic too?

I was topping out at 7'500 (500 short of redline which should be raised a little by the Akra map, so maybe 900 short of the rev limiter) and 194 km/h.

He is running stock final ratio, 16/40. I was geared tall 16/38.

Today I have taken Kev's (O2 controller Kev) advice and geared down by re-fitting a 15 on the front and an orange 42 on the rear. 2/40 + 1/16 = 11.25% reduction from stock. 7'500 x 11.25 = 8'437 rpm, which should be 500 short of the rev limiter at 194 km/h: theoretically that gives me 205 km/h at 8'900. Fingers crossed; I may see that 200. I still won't be able to test terminal speed until I get to the track - it's not worth it.

Geared down and about a 10mm shorter wheelbase. Wheelie time.

I've had too many beers to test it, and it is dark. Stay tuned.

 

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Discussion Starter #3
I won't deny, RR, this thing is like an ultimate Meccano set for grown men who are meant to behave better.

Total cost for this mod: less than $150. Well worth a try. It think I am just addicted to trying different set ups on my Meccano bike. But for $150 (Orange 42 sprocket $109); this mod gives you more "settings" by mixing and matching the front and the rear; the changes in feel of the bike are as big, at least, as changing the ignition map. 60km/h is best in 4th gear now, but still with a "theoretical" top speed of over 200. I am going to leave it at the most lowly geared set up for a while - until my excitement calms down, I get used to it and I can give an non-emotional report.

After the "first squirt" down to the shops for milk this morning: I am excited.
 

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Discussion Starter #5
Boldor - We now expect you to pull any DUKE 3 on straights!
S'not going to happen with the 15/42 set up 4'500 rpm sees 95km/h in sixth gear. So I am reckoning it'll have Buckley's of getting much near 180 km/h.

But Fcuk it's fun!

It feels like a dirt bike with road capabilities. Not as harsh and raw as a true Motard, but a lot closer than the stock set up.

Kev was onto something with the suggestion to gear down. At 15/42 I think I have overdone it in a practical sense. 110-120km/h is more vibey now, but the engine feels happier. Wiwwee, I am guessing you'd do your load over my bike at present.

I have always been better at power wheelies exiting corners; I don't have the balls for point-of-balance stuff. Corner exit power mingas rock my sox. My Kato now does them in third gear with me hanging forwards on the tank.

If you don't spend much time above 120km/h, this mod is awesome.
 

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I will be following you shortly with that "Orange 42 sprocket " :)

I'll leave the countershaft at 16...
 

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Been running 15/42 on my Duke III and love it in the mountains, but it gets a little tiresome during highway droning there and back. Still, the trade-off is worth it, once the corners arrive. I'll do a 520 conversion eventually - might go down one tooth in the rear then... or not. Will definitely go for the trick orange kit shown above!
 

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Discussion Starter #8
I will be following you shortly with that "Orange 42 sprocket " :)

I'll leave the countershaft at 16...
It's six and two threes whether you change the front down a tooth or the rear up two. 1/16 approx = to 2/40; actually the front is the bigger change.

So you are accusing me of what you want to do yourself Orange Man.

I think your option is a good one though 'cause it'll reduce your wheelbase too.
 

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Actually there IS a difference whether you change the front or the back but it isn't in the ratios. A change to the front sprocket has a larger effect on the angle and offset of the chain to the swingarm rear sprocket to swingarm pivot. On a road bike this a noticeable as rise/squat differences in accelleration and at high loads ( Duke riders NEVER apply high loads of throttle......er....) will change the traction and suspension height during cornering .
Also if you are using steel sprockets, the bigger sprockets have a much larger effect on acc. and unsprung weight because even a few teeth is a lot of extra steel.
By the same token, a larger rear sprocket will reduce the tooth load and wear.
Remember not to have simple ratios between sprockets as that increases chance of asymmetric wear. Avoid things like 14/42 ( 3:1) or 15/45. Even 14/49 ( 2.5:1) is a bit iffy.
 

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Been running 15/42 on my Duke III and love it in the mountains, but it gets a little tiresome during highway droning there and back. Still, the trade-off is worth it, once the corners arrive. I'll do a 520 conversion eventually - might go down one tooth in the rear then... or not. Will definitely go for the trick orange kit shown above!
It already is a 520. Plan B?
 

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At my recent trackie, the 2008 DukeR which has been remapped, but is identical to my set up otherwise, cleanly pulled past me on the straight. Don't worry, I have a therapist.

Also, his dyno run gave him no more than 1/2 a hp over me.

He is a smaller and lighter rider than I am, but that shouldn't alter terminal speed. He might be more aerodynamic...
Have you changed bikes and had a go on his to be sure "the bike" is faster ?
 

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Boldor - Is your mate's 2008 running an KTM Akra? These bikes are very sensitive to the exhaust length/volume/flow - I'm positive if you added the TI Akra exhaust you would out run all DUKE 3s....you have the cam, airbox, Acra map....and a straight pipe eliminating the cat...not sure if this is a good thing...for optimal power/torque with the Akra map...

What gearing (front/rear) is that fast DUKE 3 running ?
 

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Question: If the rear sprocket was to be changed from 40 to 42, is a new chain required or is there enough adjustment to fit the larger sprocket?
 

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Discussion Starter #16
Have you changed bikes and had a go on his to be sure "the bike" is faster ?

Cop a load of this cheeky Fella. (said pointing at the tall man)

All I can do Wiwwee is set up my final ratio to be exactly the same as Phil's at our next trackie. Phil is kinda anal retentive about his Baby. He doesn't care for Bolder's history of binning it. I am not allowed "a go" on his Lass.

I was concerned about your suggestion until Phil just motored past me half way down the straight.

But leaving lap times alone for a mo.

I have ridden the new 15/42 set up for a while now, approx 300 km. It is staying!! It'll need to be geared up for the track, but on the streets is marries up the gearbox and the motor just beautifully. It makes the Duke the bike I have been looking for since I bought it. If the option of bolting on more power comes to me, I'll take it, but for now I am very happy. I was trying to make 1st useful and leave 6th for the track. After much torment, I have taken Kevin's advice and let go of first and made 6th useable on the road. This set up rock's the dog's nuts.

15 or 16 front, 42 rear plus engine mods giving 70 hp rear wheel is heaven.
 

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It already is a 520. Plan B?
DAMN!! You're right, Roadrogue! I'm so used to doing 520 conversions on my bikes that I just assumed I'd have to do it for this one, too. And the sprockets I've bought for the Duke so far have been from websites that pre-select parts to fit your particular bike; I never had to specify anything but the number of teeth I wanted, so I never had to check the specs.

I really should have paid more attention. I bought an ugly/heavy rear sprocket for (sort of) cheap, thinking that I'd save some money for when I switched to 520. I should have just spent a bit more for a really nice one from the start! At least now I won't have to replace the chain, as it's only got a couple thousand miles on it.

Okay, so Plan B will be to slow my impulsive arse down and think this through a bit better before I buy the next setup...
 

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Discussion Starter #18
Boldor - Is your mate's 2008 running an KTM Akra? These bikes are very sensitive to the exhaust length/volume/flow - I'm positive if you added the TI Akra exhaust you would out run all DUKE 3s....you have the cam, airbox, Acra map....and a straight pipe eliminating the cat...not sure if this is a good thing...for optimal power/torque with the Akra map...

What gearing (front/rear) is that fast DUKE 3 running ?
2008 DukeR with underslung Akra. 16/40 as per stock.

I don't think that singles are very sensitive to pipe length as long as you are letting it get the gases flow. Exhaust tuning is much more relevant to multi-cyl jobbies.
 

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I'm running 15/40 now (one down in front).
I think I might go to a 41 or 42 rear as well, as I definitely like the 1 down in front - reckon it could be more tho!
 
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