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Discussion Starter · #1 · (Edited)
Its been 2 months since i changed the standard 45 tooth rear sprocket to an aftermarket 43 tooth rear one and have been pretty smitten with the results...

Today, decided to do a "back to back" test on the 43 and 45 tooth variants:

Took the bike and the 45 tooth sprocket to the local bike shop and got them to take the 43 tooth one off and replace with the 45 - "yow've got too much time on yer bleedin' hands" i think Uncle Percy would be saying about now"....

No real prob, they are as cheap as chips and within 15 mins it was fitted and i was riding up the road....

The plan was to ride the 390 about for a week with the 45 tooth sprocket and then decide if to keep it on, or revert back to the 43 tooth one....

Here's my comments:

As i rode off, i had forgotton how short geared 1st and 2nd gear are.... was quickly into 3rd and off i went....

Then i noticed how "clunky" the gear changes were, and how "jerky" the bike was....

Got on to dual carridgeway and opened it up - certainly didn't pull as well with the 43 tooth......

came to a stop at a set of lights - pulled away in 1st, but needed 2nd sttraight away, more clunks when changing gear.....

i got to the first U turn and turned back to the bike shop to get the 43 tooth item back on, cos no way could i live with the 45 tooth any longer....

Smiles all round from the mechanics as they changed back to the old sprocket - total labour was equiv of $4 USD - so "nothing ventured" and all that....

Did the same journey with the 43 tooth sprocket:

Here's my comments:

1st and 2nd gear much much longer and smoother, gear changes smooth as silk, mid range power delivery very smooth, "jernyness" almost none existant...

On to the dual carridgeway, bike pulls smoothly and feels that it would achieve a higher top speed (too old for all that lying on the tank nonsense and riding flat out)....

For the equiv of the $43 usd the 43 tooth sprocket cost, it has totally transformed the Duke into a nice tractable bike that can pootle round town, but wang open the throttle, it pulls like a steam train...

Sprocket came from Tyga Performance in Thailand.
 

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Hi Proper,
Thanks for the write up, I too have noticed the exact same scenario, 1st and 2nd are very short and the jerkiness
I've been thinking about changing the rear sprocket to a 43, just want to confirm, there is no need to remove a link in the chain?
 

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I think ol Pork should have tried the 43 before he threw in the towel. I'm going to put a 43 on mine this winter. I had the same experience with a 250 Ninja years ago.

I'm pretty sure the chain adjuster spacer thing, can be rotated to work.
 

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Discussion Starter · #4 ·
Hi Proper,
Thanks for the write up, I too have noticed the exact same scenario, 1st and 2nd are very short and the jerkiness
I've been thinking about changing the rear sprocket to a 43, just want to confirm, there is no need to remove a link in the chain?
i went to the trouble of buying a connecting link, but the guys fitting the sprocket said it wasn't needed as there was plenty of adjustment...

Also as the chain wears, you can turn the adjusters round, so you can get the correct chain wear on a 43T without havin to remove a link....
 

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Discussion Starter · #5 ·
I think ol Pork should have tried the 43 before he threw in the towel. I'm going to put a 43 on mine this winter. I had the same experience with a 250 Ninja years ago.

I'm pretty sure the chain adjuster spacer thing, can be rotated to work.
yes i agree....

riding a fully run in bike with back to back 45 and 43 tooth sprockets, shows how jerky and poorly geared the standard bike is.....
 

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Discussion Starter · #6 ·
Hi Proper,
Thanks for the write up, I too have noticed the exact same scenario, 1st and 2nd are very short and the jerkiness
I've been thinking about changing the rear sprocket to a 43, just want to confirm, there is no need to remove a link in the chain?
I think many members are putting on costly "piggy back" boxes trying to eliminate the jerkyness, but i cured it (plus a fair few other niggles) with the 43T, which costs an n'th of a piggy back box.....
 

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You should try a correctly fuelled 390, none of this overdrive nonsense to get it "smooth", you're just making the felt effect of the weaker by giving the engine less leverage on the back wheel.
 

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Discussion Starter · #8 ·
You should try a correctly fuelled 390, none of this overdrive nonsense to get it "smooth", you're just making the felt effect of the weaker by giving the engine less leverage on the back wheel.
Each to their own.....

I have not tried a piggy back box - just seen numerous comments about them not working out of the box and not being plug and play, frustrated purchasers frantically swapping e mails to the manufacturers, trying to get the produce they purchased to work properly........

Porky's comment "Yes I'am disappointed,a Yam or Honda or any of the major brands works out of the box" does ring true, but having forked out $5,000 USD or so on a new Duke, you're clutching at straws to get rid of the jerkyness....

As far as fitting a 43T sprocket - for me it was a cheap way of transforming the bike and works well for me.....if you'd rather pay 10X that on a piggy back box, no prob - its your money.

weather i would have been better off buying a 500F (which costs about $400 USD more over here) which as Porky says "works out of the box" - who knows.....

maybe a 43T AND a piggy back box is the way forward, but its money you'll never see again when you come to sell it (oh you're keeping it for ever ?? - Thats ok then).....

just my tenpenny worth...
 

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Each to their own...
I was going to say this and cudos to you for achieving happiness with your bike so soon! Personally I've never been truly unhappy with the Duke, but every improvement I've made has made it a more satisfying ride.

Although saying that a piggyback and a 43t achieves the same thing is a bit of a copout. A piggyback sorts out the fuelling, the inherent problem, a 43t just hides the fuelling problem better than a 45t does.

Part of owning a 390 is tinkering with it, obviously not what duke of pork was after, but if you're happy to tinker, its a much more capable bike than any of the other manufacturers offer in this class.

Three cheers to the aftermarket!
 

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I think many members are putting on costly "piggy back" boxes trying to eliminate the jerkyness
I agree.

Thing is though they then find they not only eliminate jerkiness, they also get a much more impressive bike altogether as a very pleasing by product.


maybe a 43T AND a piggy back box is the way forward, but its money you'll never see again when you come to sell it
No reason why you cant see a good proportion of that money again (just as you will only see a proportion of the bike value itself) by simply removing and selling separately.

I do not doubt a 43t sprocket is a good mod but having now experienced it I'd much rather have an (estimated) extra 8hp in the midrange from my powertronic fuel controller that I just plugged in (no emails to the manufacturer) and also fully expect to be able to resell on ebay for a good price any time I feel like it (which is probably never) :D
 

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I can say yes. I did it. 42 sprocket with Rapid bike easy. Completely new bike.
I'm finishing the mods if it's possible painting the tank case with a pearl white and new sticker and I will create a thread to show everything.
Luis
 

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Discussion Starter · #12 ·
I agree.

Thing is though they then find they not only eliminate jerkiness, they also get a much more impressive bike altogether as a very pleasing by product.




No reason why you cant see a good proportion of that money again (just as you will only see a proportion of the bike value itself) by simply removing and selling separately.

I do not doubt a 43t sprocket is a good mod but having now experienced it I'd much rather have an (estimated) extra 8hp in the midrange from my powertronic fuel controller that I just plugged in (no emails to the manufacturer) and also fully expect to be able to resell on ebay for a good price any time I feel like it (which is probably never) :D
8hp is the neck end of 20% power increase on a 43hp bike.....

i would doubt if you could get half that...3-5% is a realistic increase on a non turbo engine...

And congrats on your piggy back box being "plug and play" - its a pitty that many Duke owners trying to get rid of the jerkyness, weren't so lucky.....
 

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Discussion Starter · #13 ·
8hp is the neck end of 20% power increase on a 43hp bike.....

i would doubt if you could get half that...3-5% is a realistic increase on a non turbo engine...

And congrats on your piggy back box being "plug and play" - its a pitty that many Duke owners trying to get rid of the jerkyness, weren't so lucky.....
From T'internet:

Mythbusters: A Stock Bike Makes More Power With A Custom Map

"Here's a look inside the state-of-the-art Bazzaz dyno room where Bazzaz tech Jason Boone performs the first step of running a test of the CBR1000RR ......"

"map showed a 2.21 HP/1.14 LB-FT improvement"

so 2,21hp increase on a 134hp bike at the Bazzaz Dyno room.....

Full article:

A Stock Bike Makes More Power With A Custom Map | Mythbusters | Super Streetbike
 

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From T'internet:

Mythbusters: A Stock Bike Makes More Power With A Custom Map

"Here's a look inside the state-of-the-art Bazzaz dyno room where Bazzaz tech Jason Boone performs the first step of running a test of the CBR1000RR ......"

"map showed a 2.21 HP/1.14 LB-FT improvement"

so 2,21hp increase on a 134hp bike at the Bazzaz Dyno room.....

Full article:

A Stock Bike Makes More Power With A Custom Map | Mythbusters | Super Streetbike
..and of course all bikes are in the same state of tune, especially when compared to top dollar superbikes? Are you kidding me?!
 
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@properperson think I read you'd owned 57 bikes - were any of them big singles (500cc +) ?
 

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Discussion Starter · #19 ·
Anyway, i have listened to 640 and Mal....

Having done the 43T - i'm taking the plunge and having the Octane Max 2 box fitted on Thursday....

Equiv of $225 USD incl them fitting it and setting it up....(almost half the price of the Powertronic box here cos of import duties)

Top company - told me if i'm not 100% happy, they'll take it off and i ain't got to pay - Can't say fairer than that....

looking at the video, firstly they look exceptionally knowledgeable and secondly it looks a slick bit of kit...

Link - http://www.ecu-shop.com/
 

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had an XT500 decades ago.....

ps am i being led down a garden path ?
If the octane max box does what it should then my guess is the midrange torque increase will remind you of it
 
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