is it possible/legal/safe to make a composite tank for a streetbike?
From what I hear it’s not legal in the US, but the laws in Canada may be different.
I would not want to do it due to liabablity issues. If the bike gets lay down or fall off the kick stand (Do they still have those?:o) the tank can get ruptured.
I think there a thread or two on here talking about it or at fiberglast…but with all their spam…
A carbon tank would be so cool, there are places you can go to have a rubber membrane sprayed onto the inside of any tank, I looked into this as a solution for a leaking tank of mine once. This would give a good amount of protection form any leaking due to laying the bike etc…
I figure that if the tank is made using csm with layers of fiberglass cloth and layers of kevlar throughout it would be reasonably safe.
A composite tank made of csm alone is going to be pretty safe on a road bike. However if composite tanks are banned for road use in your location, then this isnt really going to make a lot of difference as you couldnt use one anyway.
I’ve seen them before on streetbikes, best answer I know 
IMO, you’d be better off overlaying the steel tank with CF for the look.
This would be for an older ducati F1 bike. The owner wants a lower profile tank similar to the ones used on the actual race bikes of the period. The tank would be painted and would not use any CF. Owner is a personal friend who rarely rides and is very conservative.
Little F1 trick…fill the tank with pieces of foam rubber, this will help prevent explosions.
But how are you going to add the gas filler and petcock into a new, one off tank?
Maybe hit the bike swap meets and find a glass one from a Bultaco or such and use it or modify it?
how can a composite gas tank NOT be legal, they use composite windings to make pressurized gas bottles. True its alittle different application and manufacturing process. Maybe thats the difference though.
I think the legality isn’t what should be discussed here, since the laws differ from region to region, and nobody’s actually supplied any sort of legal proof as to their claims.
RATHER, the saftety aspect should be what we’re discussing here. Simply put, because of unknown interactions between the various fiber reinforcements, matrixes, and fuel types and blends, the tank’s integrity cannot be guaranteed. UV degradation of matrix materials is yet another variable.
Further, whereas metal tanks will buckle and dent with critical impacts, ideally retaining their structural integrity, composite tanks will shatter and crack. Not good for something holding fuel.
In my opinion, there are just too many variables at play here…composites are great, but there’s a time and place for everything, and I don’t think fuel tanks is the place for composites of the type we’re dealing with here.
FOZ (hey, we have a “FOnZie”
on here…) that was right on the nose!
Thanks Werksberg!
Someone made the comment earlier that an overlay on a metal tank might be the way to go…I totally agree!!
Again…Not for asthetics. I appreciate the comments and am starting to agree that due to the interaction of gas and composites, along with the lack of buckling in a composite tank, I will need to do a considerable amount of more research before actually putting this into application.
Seal the inside with a membrane, add kevlar to the matrix and call it a day!
They exist, so it works.
Plus, any tank will most likely have a coating on the inside, which you can get at most car part stores, and motorcycle parts dealers, for repairs. I’m sure a search can provide many tank linings for use in composite tanks.
And, as said before, some of the most indestructible tanks are made out of CF. It’s trial and error.
My experience with composite tanks in the racing industry is that sooner or later they will start to break down and leak.
They always have and always will. It seems to be a problem with the alcohol added to the fuel.
Classicbike has a neat way of doing them…Id like to try it.
He bonds the two halves together.
Id like to try it out…but hesitate.
Well of course you need a liner or bladder system to prevent impact explosion. Maybe I thought that would be assumed.
And I know that some viynlEster Resins are fuel stable and will not degrade. That might change with the addition of Alcohol type fuels.
http://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/28890cc.pdf
http://www.carbonfiber.gr.jp/english/tanso/use04.html
And here is a guy that actually made a CF tank for his Bike.
http://www.mci.i12.com/carbon/petrol_tank.htm
Also, fuel cells used in most racing circuits are a molded polyethelyne(sp?) type with a steel case surround. Foam blocks is to prevent sloshing not anything with impact, and have a rollover vent incase of…well rollover.
But in all honesty, we’re dealing with a motorcycle. If the impact is great enough to puncture the tank the impact will most likely send the rider well clear of the bike anyways. j/k
Simply put bikes, IMO are very dangerous regardless!!