Ok guys i have an idea here and i need some input from you guys. Ok so here we go.
I work in a factory that makes oil and fuel tanks among other bits and bobs out of high grade plastic. Its all done via rotational moulding. For those of you who dont know what that is, it is basically metal moulds filled with a specific weight of plastic powder cooked for a certain lenght of time to form the desired tank. So here is my thinking. Every fuel tank that is made from sheet metal battles with rust issues eventualy, this as some of you know causes pin holes which then causes the tank to be lined or brazed. My thinking is if i was to get the mould made of the 750 tank it could eliminate this problem. Here where i work my boss is easy going and wouldnt mind me doing it at all. Also as for the likes of the petcock and tank lid etc etc. We can also add brass inserts into the mould for screwing this stuff on. The inserts are formed into the plastic. What do you guys think. Would you use a plastic tank. Thickness is not an issue with it as i can make it as thick as i want so strenght is no issue.
I can remember when lightweight fiberglass tanks were used for racing bikes. They were eventually banned as they had little impact damage resistance and would burst when the bike was dropped. I am sure you have access to a material with better impact characteristics though. My bike has a dent in top of the tank from where it was dropped by the PO.
Rather than mold the existing tank how about one with an extra gallon in it?
I see where you coming from with the fiberglass. The plastic we use is weather resistant and also does not crack under load or if dropped. I have had 200kg tanks fall from the hoist at 16ft and never left as much as a mark on it. The thing with the moulding is that they can be made as big or small as i want. Extra gallon. No prob as long as the mould is big enough. The thicker the plastic the stronger it is. Most of our oil tanks are 5mm thick but some go as far as 16mm thick for the chemical tanks.
Well if you’re going to go, go big...make that 2 gallons larger
My only concern on plastic tanks would be paintability. Is the surface smooth enough and how well would paint last?
I had a plastic tank on a dirt bike and it looked OK for a dirt bike, but some might consider it ugly for a street bike. Wasn’t shiney and the plastic finish degraded over time from sun exposure.
It is however a good idea, especially since the supply of stock tanks are slowly dwindling.
A few less gas station stops on days you plan to take a long ride would definitely pique my interest. I haven’t had to take my tank off yet, but you all on here make that sound fairly quick and easy. So I’d be interested. Of course would like to see it on another bike to see if the bigger tank looks good. Be curious to see how you’d maintain the handle bar clearance and what not.
Im in ireland. As for the cost. Well the plastic would be free to an extent as would the whole cooking process as it would just go in the oven with other moulds. So the only real cost would be the actual mould itself. . Im not sure on the paint adhering to the plastic but im sure if it was painted with a plastic primer base coat the top coats would hold to that. Im not thinking of the making money side of it altho it would be a good oppertunity for a small business. Im more thinking of it as a solution for a problem that i myself am sick of dealing with.
I think it's a great idea, ESPECIALLY with the added fuel capacity. I think people would "upgrade" to plastic just for that.
Something else to consider, the gas caps for the vn750 seem to be in short supply. Making the orifice compatible with a more plentiful gas cap replacement part instead of the stock cap would ease that pain as well.
i no what you mean. Thats the beauty of the idea. Maybe a universal kid of gas cap. Nothing oem just reproduction kinda ones. I think i will look into this further. We have a team of Cad mould designers and i might be able to get one of them to draw up a sketch of the mould. That way i can get a rough estimate on tje price of it. We have a team of mould makers also but there always busy and cranky so if i go ahead with this i will get it made up elswhere.
Even just 1 gallon larger would be an improvement. That should get you a 165 mile range, versus 122 miles, as long as it doesn't ruin the looks.
I like the gas cap idea. Could design it to use more readily available caps, and caps that have varied styles available in the aftermarket, so everyone can find what they like. Could maybe see what styles are available in threaded caps, which would eliminate the need for threaded inserts. Not sure what's out there with the threaded type, besides the dirt bike market. Bayonet types are usually not interchangeable between makes, so you may have to pick just one, unless molds aren't a huge cost factor. I'd say Harley is going to be the widest selection in the aftermarket.
Painting plastic is no problem. Plastic can be wet sanded easily, and there's all sorts of plastic paints, even a chrome process, real looking chrome not just silver. Can probably prep a plastic tank quicker than metal, and plastic rarely has dents.
There's also hydrodip, available in more colors/patterns than a person can imagine. For the most part it's very inexpensive, quick, and easy. Cost increases when you have parts needing a larger dip tank, like atv bodies, which I'm about to try. I'm on the lookout for a 12' EZ-Up swimming pool.
Dirt bikes have had plastic tanks for a long time. My Yamaha XT225 came with a 2 gallon steel tank. I replaced it with a Clarke 4 gallon plastic tank. But it is a dual sport bike used mainly as a dirt bike. A cruiser might look a bit odd with a plastic tank. I still wax the paint on my cruisers. But a bigger concern would be ethanol. I had the oem tanks on 2 Honda dirt bikes destroyed by ethanol. It happened while they were sitting in a shed with ethanol gas in them. I went in the shed and could small gas. I looked at one of the bikes to see if there was a leak. I rolled it outside and discovered the tank had cracks all over it. I checked the other one. Same thing. Both vents were open, so it wasn't pressure. The ethanol broke down the structure of the plastic tanks. When I'm not going to use my XT for a while, I remove the tank and flush it out with water, and drain the carb. A 4 gallon Clarke tank is about $300 bucks.
I was looking at some of them caps yesterday spockster. I no some people like locking there cap with a key but to me a screw in one would not matter. It would make the design of the mould cheaper and easier as the fittings would be standard enough and a lot easier to mould into the plastic as we do that already on some of the portabale tanks. I put a pic of one of the fittings below. This is only one type but there are many and i could use one that would fit the screw in caps.There is also a pic of the small fittings that could hold the petcock on. I would actually kind of prefer it to be honest. Vn750rider/jerry as for the plastic breaking down with the fuel, this wont happen as the plastic i work with is for this purpose with a lifetime warrenty on the tanks. As for making it a gallon bigger, im thinking if i keep the original design and just make it that extra bit bigger it shouldnt take away the look. This plan will be put in motion today when i have a chat with the design team on the quite. Might have to slip him 50 bucks to keep it low key as he has his own work to do. I shall post back later with a rough estimate on the cost.
I tried looking at female threaded caps, as on dirtbikes, but there's just so many. Male threads on the tank means you don't need a bung insert, just mold the threads on the top of the tank. If the threads are just the right height, I don't think it would look too bad. I suppose you could mold female threads on the tank as well though?
Jerry, what year is the XT? Plastic tech has come a long way since then, and maybe ethanol wasn't even in widespread use then?
Yes we can do the female threads also but my only concern with that would be stripping out. We have a variety of brass fittings to be moulded so i will have a look and see what would suit
I'd consider using a plastic tank if the capacity is larger. My commute is 37 miles one way. If I'm light on the throttle, I can get two days on a tank (148 miles), but that rarely happens. I end up fueling up every day. I'd love an extra gallon or two!
I have the design team working on a drawing as i type this. He is doing it in his spare time but should be ready by monday. Amazing what 50 bucks can get you 😁
Ethanol is a spooky fellow. I always fill mine up with ethanol-free if I'm not going to immediately burn it off on a road trip.
As for the tank, this project seems like a lot of fun! A small production run of a greater-capacity tank is the kind of crowdsourcing project I love seeing on forums like this (if it comes to fruition, no sweats one way or the other)
I plan on keeping this thread up to date as i go along. It sure is gonna be a fun one. The beauty of it is that once the mould is desiged and made 🤞 all the fittings like for the petcock or fuel level fitting are added afterwards. My thinking on this so far is.. petcock fittings, fuel level fitting(optional) when i say optional i mean the fittings for the screws will be there but no hole for the actual thing itself. The hole can be drilled by the person themselves if they choose to use it. Gas cap will be moulded into the tank. I was also thinking of having fittings in place for the option to add an auxillary tank if one so desiers. This would give the person the option of having an extra gallon tank stashed somewhere else on the bike. This would also have the fittings in place but need to be drilled out also. That is my thinking so far on it.
I think to make it bigger the best way is to make it wider. If you change the side profile it will change the lines of the bike. Unless you are going for a Mad Max look. I carry an extra gallon in 1 qt bottles if I have any doubts about running out. My first 2 Vulcans would go on reserve at around 120 miles. But since it has tubeless tires, I don't have to lug around all the stuff you would need to repair a flat tube type tire. I have saddlebags, a T bag, a tank bag, and have room on the passenger part of the seat for another large bag, which also provides back support. I have always been "mission specific" I carry what I think I will need on a specific trip.
I believe Harley v-rod uses a plastic tank.
It has a sheet metal cover over the engine where a standard tank sits.
The tank itself is relocated under the seat, plastic molded to fit the tight spaces. It’s protected by frame, but has passed Harley and dot safety standards. And I like the idea of new availability to meat demands. As well as no rust regardless of how long it sits.
This vn is now my 7th build. And I always dread the tank battle.
New tanks, restored tanks. Custom, etc. rust removal. Parts to fit. Etc.
but price point would make a new production plastic tank worth worlds to me.
Especially with availability of multiple styles and designs.
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