Project: 500GP

[maviczap]

Nice work Steve!

[squirrel_hunter]

So I'm getting a little tired of footpegs. All I have to do is a bit of finishing and then some chemical experimentation so I've decided to take a little break and turn my attention elsewhere. Something simpler for a bit. The petrol tank.

I've been looking at a few options, simply using the original was ruled out, it needs a bit of finishing and a repaint but I want something to keep in line with the 500GP theme. I found a company that was advertising a fibre glass tank, but they were out of stock and unlikely to manufacture any more anytime soon. I then found another that did a fibre glass tank and seat unit but the fuel cell was only a couple of litres intended for track and not for road use which even considering the theme is what this bike is intended for. I asked about a larger fuel cell but that wasn't an option. I ended up with a fibre glass shroud and considered making a base for it but wasn't sure on the exact petrol resistance of the composite so ruled that out as well. So I was thinking I'd be limited to reuse the original but I started thinking about rust and the work the 2MA tank needed and to my surprise listed on eBay via India reproduction tanks where available.



The only issue with the India tank I could see were that they were some distance away and I couldn't be sure of the quality. A friend bought one for a XT500 based build that he picked up while over there and while the service was great the overall quality wasn't what he was looking for and so ended up not using it on his build. But I had an idea if I could get it for the 'local' price the gamble would be worth it, so one of my team sent his bother over to have a chat, and yes they would be happy to make one for him but they knew what was going on and there wasn't a 'local' price. I don't blame them for that at all, it was a little cheeky on my part.



But the Indian company stayed in my thoughts so I emailed them and we talked about a couple of options and they were very accommodating. So after about 6 weeks of waiting and a little extra on the price tag a box turned up containing a tank built to my specifications. In short I asked them to build me a tank but to put an extra filler cap on it for me. They were happy to do that for me.



Oh and I also asked them not to weld the top to the bottom. You see I had an idea but to execute it would be challenging to fully explain via email so I thought I'd get them to make the most and for me to finish it off. So the idea is simple and was inspired by endurance racers that have a functioning twin filler, but why do I just need two fillers to get petrol into such a small bike, well take a look at the quick release fillers I'm going to use.



You may notice one is red and one is silver. This is for a simple reason, the red one is for oil, the silver for petrol. The only problem is at the moment apart from having no bottom both fillers lead to the same point. So I need to section this off and divide the tank up. I shall start by turning a boss down on the lathe. 24mm OD and 19.5mm ID. This is for the oil level sender because I might as well. This was inspired by some of the vents on tanks on NSR250 and VFR400's from the same era if memory serves.

So not content with a big hole in the bottom of the tank I added another to the top.



But don't worry this is for the boss to sit, time to break out the welder...

[squirrel_hunter]

With the use of the TIG welder I stuck the boss I made on the lathe into the top of the tank. I'm pleased with it, no pictures of the weld bead up top as I took it all back with the Dremel as I'm not good enough to lay a nice bead down yet. And if anyone is looking for investment recommendations, car body filler suppliers.



Anyway the inside I left. I think there is enough on there to keep it oil tight and as they say the bigger the glob...



From the outside this is a representation of what the finished tank will look like with the caps and sender in place.



My next job was to run a tap down a couple of the cap mounting bolt holes as there was at least one that was a bit crunchy. This turned into a bigger job then expected as the cap on the nut was thinner than tin foil resulting in the tap passing straight through. So I decided to throw some weld on as well as giving the nut some extra as it wasn't clear how that was being held on.



The caps were so thin that they melted away as soon as the TIG torch got close. With the first one I put a stainless bolt in to protect the threads as from experience with the MIG I didn't want to damage the remaining threads. However I now discovered its possible to weld steel to stainless. So that was ground back leaving no threads so I rebuilt the entire bolt hole with weld, drilling and tapping, before sealing over like the rest. Then I discovered that as I'll be using aftermarket caps that bolt hole isn't used anyway.



Next was some CAD, Cardboard Aided Design. I needed a template to make the tank divider from and picked a spot near the front of the tank, the idea is to have more petrol than oil in the tank.



From the card template I cut it out of some steel sheet I ordered and then stuck it in to weld.



And this is where I hit a problem. As soon as the torch got close the new sheet would blow through. Turning the amps down on the welder eventually helped in that it wouldn't instantly hole, but it then wasn't powerful enough to pool the outer tank metal to properly fuse. While I got a couple of tacks in that wasn't enough and would give problems later. So out it came. I'm going to look at my options here, I'm thinking either wrong type of metal or it needs to be thicker. Either way that will have to wait until the new year.



So I chucked a bit of red oxide primer back over it to protect the metal until the next time I can try...

[CheGuevara]

We got the YSR50 & 80 in Canada -rode a few, came close to buying one on a couple of occasions. Loads of fun (and way-back memories) so I'm enjoying this thread.


I remember reading an article in I think one of the US magazines ages ago where a guy had stuffed a YZ426(IIRC) motor into a YSR(80?) chassis. The torque twisted the swingarm, so he had to brace it.



Anyhow, to the point (and apologies if it's been mentioned and I missed it); Rather than partitioning off the tank, have you considered fitting a plastic oil tank inside the petrol tank? Might retain a bit more fuel capacity. Or just use what you have as a cover for a plastic fuel cell and oil tank from another bike? Or use what you have to make a mould for an FRP or CF cover for plastic (or Al?) fuel and oil tanks.

[squirrel_hunter]

Yeah I've seen a few conversions with different engines, TZR125 looks popular. The style of frame makes it quite easy from what I understand as there is a lot of room available and the frame rails or cradle is removable so custom making something that just bolts in makes it in theory simpler. The thing with engine conversions is how far can you go while keeping it the same bike, I'm thinking of the Panigale Grom or the 700cc (can't remember the exact engine now) where they basically remade the entire frame. At that point without the original frame or the original engine is it still a Grom and not just Grom shaped? But I'm not taking anything away from the very impressive work that has gone into those bikes, just not sure if its something for me. Thats why I've just added a massive 7cc's to this.

But anyway back to the tank. Yeah I did consider a few of those ideas, but ruled them out for various reasons. Some of it related to how much work I wanted to take on particularly with things like making my own from CF for example. One thing with plastic tanks to consider is how they react to fuel, I had a Triumph Sprint RS that had a plastic tank, the trouble is it expanded from the petrol which made refitting once removed almost impossible. So while I could make something I wouldn't want it to then all fall apart at the first sign of fuel. Hopefully the metal one wont as I intend to test it before paint and even use a tank sealer so hopefully that will cover it.

I did think about a cover and a plastic tank from another bike but the size of the bike and tank presents an interesting problem as the stock tank is only about 8 litres. Then if I could find one I would then have to devise some way of attaching it securely to the bike which I don't think would have been easy. Maybe I'll do something like that for the next bike I build as I already have some ideas of what I want to do and the petrol tank is something that will need modified so who knows what might happen in the future...

[Geodude]

Thanks for keeping us updated on this SH

[Calix Lee]

This build is keeping you productive, thank you for keeping us posted with this project.

[squirrel_hunter]

Glacial. My pace that is. I'm disappointed at my rate of progress too. But in my defence

Anyway.

So I've been getting into reductive 3D printing.

The TCR top yoke was good but I always had a little reservation about it as it had been modified for reasons I was never sure of. So I decided I might try and make my own. But I was a little constrained by the machines. To do it on the Bridgeport would take a lot of time and there are lots of setup complications that I found when making the rearsets so put it on hold. We did acquire a Boxford VMC at the workshop and while it was good I very quickly ran into size constraints. So with no other option I had to wait until one day a Bridgeport Interact MkII magically appeared. I say magically, we measured the width of the machine against the entrance multiple times and found it would fit, what wasnt measured was the hight. Lets just say it was an interference fit to get it in the space even after some disassembly. But that was not the end, 3 Phase electricity needed to be added and all this took time, but eventually we got it running.

Thus I designed a yoke in Fusion and cut it in ply on the laser, it needed a couple of iterations until I was happy with it. Time for the reductive 3D printer, but first I took the stock to height on the manual Bridgeport with a facemill.



The first step was to drill the mounting holes for the lock. I did this on the CNC but manually to save on setup. Next was to bore the holes for the forks and the stem, this was via my program. Unfortunately it needed some modifications as a nipple on the stem bore converted a 4 flute endmill into a 3 flute, its all a learning experience.



And so all that was left to do was to cut out the yoke. This brought an additional learning, tabs in Fusion, dont put them on corners as one the part is out you'll spend more time filing them off.



Back to the manual Bridgeport to drill and tap the clamp bolts and slit the clamping space. I need to change the order of operations for the next go for ease as well as lengthening the clamp bolt threads as I've only got a 16mm bolt in there and would like a 20mm M6.



But the test fit on the bike went well. I just need to improve a bit of the finish and it should be good to go. However I am thinking about weight, the stock pressed steel yoke is 352g, the TCR yoke is 289g, my yoke is 357g. So slightly heaver then stock, but much heavier than the TCR, I'm thinking I can pocket out a bit of material from the underside of my design to bring the weight down to under stock.



But either way I'm happy with the look, and think that the bottom yoke will come out under weight of the standard item but thats something for another day...