Kawasaki VN750 Forum banner

1 - 20 of 27 Posts

·
Registered
Joined
·
142 Posts
Discussion Starter #1 (Edited)
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.
 

·
NewB to Vulcans
Joined
·
220 Posts
MY ten cents

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?
 

·
Registered
Joined
·
142 Posts
Discussion Starter #3
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.
 

·
Registered
Joined
·
8,337 Posts
Price would surely be one deciding factor, along with shipping. I sense you may be in the UK?

We've seen quite a few gnarly tanks, I bought a new OEM tank myself due to damage, so there is a demand from time to time.
 

·
Super Moderator
Joined
·
11,972 Posts
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.
 

·
Premium Member
Joined
·
736 Posts
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.
 

·
Registered
Joined
·
142 Posts
Discussion Starter #7
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.
 

·
Registered
Joined
·
1,355 Posts
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.
 

·
Registered
Joined
·
142 Posts
Discussion Starter #9
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.
 

·
Registered
Joined
·
8,337 Posts
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.
 

·
Registered
Joined
·
8,337 Posts

·
Premium Member
Joined
·
3,027 Posts
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.
 

·
Registered
Joined
·
142 Posts
Discussion Starter #13 (Edited)
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.
 

Attachments

·
Registered
Joined
·
8,337 Posts
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?
 

·
Registered
Joined
·
142 Posts
Discussion Starter #15
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
 

·
Registered
Joined
·
552 Posts
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!
 

·
Registered
Joined
·
142 Posts
Discussion Starter #17
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 😁
 

·
Registered
Joined
·
8,337 Posts
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've never seen any strip out, the threads are really coarse. Maybe 3 threads per inch? But you know better than I about your options and costs. I think the ones with the insert, as you showed, look better than an MX cap sitting above the tank, and some of those had locks I believe.

Looks like a good project, if it succeeds you can branch out into other makes and models. If I still had the crashed tank on the bike, I'd be in line to check out one of yours.

One good thing, the tank will be a lot lighter in weight. Better, lower center of gravity, and lower shipping cost.

In making more capacity, you might check clearance between the tank and frame, see if that can be squeezed? A little here, a little there, bam, a gallon and a half.
 

·
Registered
Joined
·
142 Posts
Discussion Starter #19
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've never seen any strip out, the threads are really coarse. Maybe 3 threads per inch? But you know better than I about your options and costs. I think the ones with the insert, as you showed, look better than an MX cap sitting above the tank, and some of those had locks I believe.

Looks like a good project, if it succeeds you can branch out into other makes and models. If I still had the crashed tank on the bike, I'd be in line to check out one of yours.

One good thing, the tank will be a lot lighter in weight. Better, lower center of gravity, and lower shipping cost.

In making more capacity, you might check clearance between the tank and frame, see if that can be squeezed? A little here, a little there, bam, a gallon and a half.
I have been checking for ways with my own tank already today to see where i could squeeze the extra from. I think i can get it to 18 litres which would be 4.7 gallons. Any more and it would just look to big. This is gonna be an interesting project thats for sure.
 

·
Premium Member
Joined
·
3,027 Posts
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?

My XT225 is a 2001. It is the one with the aftermarket Clarke tank on it, which has held up so far. The two oem tanks ruined by ethanol were on a 1999 XR200 and a 2002 XR250. It happened about 7 years ago. It had already destroyed the petcock on the 200, and Honda petcocks cannot be rebuilt like the ones on the Vulcan 750. They are riveted together. They cost about $60. I drilled out the rivets, fabricated a metal cover plate for the front, and put it back together with screws and nuts. It was no longer a petcock, just a fitting. I pulled the hose to the carb off when it was stored, and replaced it with a short piece of hose with a small bolt stuck in it. Dirt bikes also have a vent hose attached directly to the center of the gas cap, and stuck down behind the handlebar somewhere (or at least they did) The open ends of these hoses would just turn to mush (including the one on my XT225)But on the two bike wit the destroyed tanks, I pulled the hoses off the cap and blew through them. They were swollen, but not blocked.

I have also had damage done to petcocks and carb parts on other bikes by ethanol. I've rebuilt VN750 petcocks 5-6 times. I had to replace the coasting enricher diaphragms on the 2002. They were completely melted. Just black goo. I also noticed the end of the carb float bowl vent hose (the one that plugs into the right side air filter housing, which I still have) becomes swollen and mushy just like on the dirt bikes.

I think there is a reason they put whiskey in glass bottles. It would melt plastic bottles.
 
1 - 20 of 27 Posts
Top