690 Rally Replica questions...

But what is about the weight now ? It is now more weight with the alloy part as before with the CFK part ? And it is still hold with four bolts ?

Weighs less, no steel centre section. Mounts the same as the other one.

Look, nearly the same:




Tail reforcement: It is not the beauty what i mean, it is may be a very well cnc or welded piece of metall, like form follows function because also the rear tank is a art of work for me and i like to have good materials on my bike so i don't have to think about it when I`m off road riding.

I hope that's dyed Kevlar. Anyone with even a thimble full of composite knowledge knows that of all of the composite materials available to the public, Carbon Fiber has the least amount of impact strength per lb. it would take half the weight of a Kevlar laminate to provide the same impact strength as Carbon, conversely, you could use the same weigth of Kevlar laminate and have twice the impact strength as Carbon Fiber.

I know Carbon is pretty, but it's only benefits come from stiffness and compressive strength.

How many Carbon Fiber flack jackets have you ever seen? Answer = 0
They are all made from Kevlar (Trade name) and other Aramid (technical name) products.

Or simply a CF outer layer so it looks nice, just like the KTM rally bash plate.

Sure, but you can purchase dyed Kevlar in very brilliant colors of Blue, Green , Orange, Red, Black and metallic (aluminized) finishes. Also, Kevlar is about 60% the cost of Carbons.

@about Steve's self-made db-killers:
I've got those two pictured, stock "KTM strangulating asthmatic exhaust items" here in my office right now ( in addition to the air filter restrictor plate ). BTW, Steve has already mentioned further up this thread how he made his from scratch.

I agree about work of art etc., but in my world carrying the Coyote saddlebag takes priority over beauty. And in my simple mind a workable solution can be self-made - or even machined by the nearest metal workshop.

I'll scratch my head and make some templates for a tail-support. Then produce a solution from aluminium or other appropriate metal. It may even have aestethically pleasing ventilation holes. Pictures will follow later this winter when done

That looks like a neat and elegant solution, but the trick is obviously to cut to shape and provide some energy-damping material behind the Kevlar fibres to save the front tanks from impact damage WHEN, not IF I go down after growing horns and fangs on the dirt.

That's the point. Kevlar is built for sustaining impacts through unbelievable tensile strength. When something impacts a material it cannot fail (sustain a hole) unless the tensile modulus of the material is less than the pressure put on it. Carbon fiber has a very low tensile rating and will not take even half the blow that Kevlar will for it's weight. Also, when Carbon Fiber fails it shoots out very sharp carbon needles that will pierce most any material and lodge themsleves into skin causing irritation and infection.

Like I said before, how many carbon fiber flack jackets and bullet proof vests have you ever seen. NONE. They are all Kevlar and Aramid becuase those fibers are designed to dampen energy through impacts. You know, like the way a rock would impact your tank should you crash or drop your bike.

I used a kevlar jacket myself in UN-service in Lebanon in the eighties and wouldn't mind making a "Tank-Impact-Jacket". Those racing guys live and breathe crucial weight saving, while my gravel-dirt-touring regime can easily live with a few extra grammes.

Besides, that colored Kevlar looks "da shit" and should do a decent job protecting those expensive polymer tanks. I'll go for that solution, so where do I order here in Scandinavia? Hmmm...this can be an interesting farkle-rich KTM-winter

Not sure about Scandinavia, but here's a good source to start, and they'll ship anywhere.

http://www.fibreglast.com/category/Kevlar

Thanks. Will check here in Norway for dyed kevlar mats too. The trick will be to shape them and provide secure padding behind the kevlar against the polymer tanks. Then I should avoid the mishap Matt of "Race To Dakar" fame encountered - holes in the tank when hitting stones etc. when I drop it.

Does anybody know, if it is possible to cover the whole tanks with foil, or do you get bubbles from the fuel?

Yes for shure you will get bubbles. May be a foil with small holes could help

The stock "KTM-orange" colour on mine appears to be some kind of foil applied by the factory. These polymer plastic tanks are known to release fuel vapours over time, so choosing the right perforated foil or correct paint may be crucial to avoid peeling.

On mine the stock, big KTM-stickers won't stick and peel off. This no doubt caused by fuel vapours gradually dissolving the sticker adhesive.
For me this is no big deal, since these peculiarities are well-known in dirtrider circles concerning plastic tanks. I simply tear off the useless stickers and apply new ones - depending on daily moods and prefs there and then

Tanks are made from a nylon it does not breath like standard moto tanks and it is paintable same as the 690 enduro tanks are paintable

Do you know what nylon? Like F650 said, my friend also had a lot of bubbling under the tank stickers. The paint had no problems however....

Pal Anders Ullevalseter told me this summer that no stickers - regardless of adhesive - would stick to those nylon/plastic (whatever) front or rear tanks for a long time. They "sweat" fuel vapours and require constant attention even for his sponsor-stickers. No big deal, really.

Goes with the territory; these tanks are made for maximum capacity and a reasonable crash-tolerance in rally-conditions within a certain temperature-range. If you want permanent stickers, go elsewhere.

In my world this is only a small rally-character treat of this bike. If you see the preps for Dakar and other rallies, mechanics use heat-guns to make sponsor-stickers hang in there for a while. Given the crash-tolerance of these tanks, that's a small price to pay.

And plastic or nylon tanks - each have their own advantages and trade-offs.
These rally-bikes are by design demanding more attention and scrutineering.
That's cool enough in my book

The KTM rally tanks are painted in a special way from the factory painter, because they heat the tanks before they get painted and ist is a little bit of mistery how they do this job. So the color get no bubbles. I let paint my tanks twice from a professionell painter, also with a different mixture of colors ( waterbasis and chemical basis ) but all the time i get after three month a lot of bubbles.

For the foils you can use different printfoils, normaly everybody use digital printfoils, but there are a lot of differences too. !

Also when you have small holes in the digital print foils the stickers will hold some more time as without holes.

When you print stickers with the offset mode and not the digital mode, the foil can be very thick and is more resist against the petrol in the tank.

Does anybody know if there is any copies of the front tanks for the 690/450 Rally avalible? And i do know of the Alberto Dottori ones, but I would like copies of the Real rally tanks.
Or better yet, some real ones, for sale second handed.
I´m about to build me own rallybike, but don´t have the funds to buy new ones...
Sorry for Hi-jacking a very nice thread...
/Thomas.