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Putting Old Girl On A Diet ( CF Wheels, Exhaust, etc )

3K views 12 replies 5 participants last post by  Hammerhead 
#1 ·
Still on the lift, having just fitted a BST CF rear wheel.
Stock rear wheel with tire , disk, sprocket, etc. came in at 37 Lbs.
It was the heaviest rear wheel I have found on a modern performance bike.
Some of my liter bike rear wheels come in at 32 Lbs.
The BST assembly was 26.5 Lbs.
Will be doing the front wheel swap and heavier fork springs, next.
My front end sags 57 mm with the stock progressive 60 - 90 springs.
Will be going to a linear 85 +/- spring.
 
#2 ·
Bike already has an Akra Slip On, along with a De_Cat.

Did that along with a Coober box.

I have found that some KTM wheels come in heavier than others.

Example, a rear wheel assembly with tire from a 390 weighed 1 Lb more than

a 690, even though the 690 wheel and tire wider. _ 33 Lbs : 390 vs 32 Lbs : 690

Was shocked that the rear wheel on the 790 came in at 37 Lbs.

Could be why the bike, overall , came in heavier than I thought it would .

Bike weighs 414 Lbs, stock ( full tank ) , and I can see it getting down to 390 or less.

Already lost 20 Lbs, or more with Lithium battery and Akra - De Cat setup and BST rear wheel.

Front wheel, next, before final weigh in.
 
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#3 ·
i agree battery change and decat removal/titanium silencer are the cheapest lightening route to take

wheels and tyres vary significantly in weight the 390 comes with cast or forged wheels market dependant.
the cheapest wheels are cast from molten aluminium, however forged wheels which is a more expensive process produces a stronger finish and hence can be made thinner, hence lighter.
this is before you consider magnesium or carbon fibre

these days carbon is the way forward with lots of options
if you go full out which you seem to be i think you will get down to 380ish

keep us informed of your progress
 
#4 ·
Heard something hit the table.
Found an exotic looking screw, wondering what part of the bike it came from.
Turned out it was the pivot screw for my breaker bar.

Extra Screw.
 
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#6 ·
The final part of the diet completed, BST front wheel.

Stock wheel and disks : 30 Lbs

BST wheel with 320 mm Brembo disks: 22 Lbs.

Bike went from 414 Lbs to 385 Lbs as of today.

The 41 t rear sprocket I ordered through Ebay still not here.

I ended up with a 40 t rear which was the only one local dealer had.

Pictures when I can get Album to load more pictures.

The pop up link to " select " from computer doesn't appear like it used to.
 
#8 ·
I think the Akra muffler and Leo Vinci de-cat knocked off about 8 Lbs.

I'm sure the wheel will make a difference in handling, from experience of prior bikes.

My favorite riding spot has had a lot of rain and snow, lately so haven't run the 790 hard, yet.

May run at Palomar in a few weeks when the road and weather is better.
 
#10 ·
Känner Racing in Germany is working on a GP2 track bike.
Pretty much custom built everything but with a KTM Duke 790 engine in it.
They state it will be 308-319 lbs ready to ride except no fuel.
Being a track only toy it has no cat, lights, indicators, side stand, plate holder and has a racing wiring harness.
But a 310 lbs bike with that engine sounds like fun.
 
#13 ·
Not being too critical, I hope, but isn't calling a machine that's been in public hands for less than a year "The Old Girl" a bit of a stretch?

Lighter wheels will improve any street machine's handling and performance, but for dirt, heavier rear wheels are sometimes an advantage (better traction, more flywheel effect, less spinning)

Since the 790 is offered in several versions, could the heavier rear wheel have been specced for the off-roaders? Just thinking out loud. I don't think KTM makes very many engineering mistakes in this regard, so there must be a reason.
 
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