Yamaha RD50MX project
Posted: Thu Jul 31, 2008 8:49 pm
I've been working on converting a 1986 Yamaha RD50MX for the past few months. I bought the bike as a couple of large boxes of bits, with lots of key parts missing, as it turned out. The best bit about this box of bits was that the frame was straight and it had a valid V5.
I spent the first six weeks getting the frame and parts bead blasted and painted, rebuilding the front forks, brakes and wheel bearings and generally getting the thing to the rolling frame stage.
Next up was the fitting of a Mars Electric LLC ME0709 motor, which turned out to be pretty easy. BTW, I'd highly recommend John Fiorenza at Mars if anyone is after a motor in this power range (up to 72V, around 150A max). He's a great guy to deal with and went out of his way to sort a shipping problem for me very quickly. The pictures below show progress on the bike so far:
The next challenge was to get some suitable batteries. I opted to use 64 off Headway 38120 10Ah LiFePO4 cells, wired as a 16S, 4P pack. Having put my faith in the ability of banks to transfer large sums of money around the globe, I was comforted to find that a very large box of cells arrived all the way from China just a few days after placing the order. Here they are, just as I opened the box:
To make the battery pack up I needed to find a way of connecting these cells together. This meant building a capacitor discharge welder, to weld nickel tabs between the cells. Ebay was a useful source for 15 ex-computer power supply, 97,000uF, 20V, low ESR capacitors for a few pounds, plus a box of very large thyristors (I still have a few of these left over). The thyristors are good for a peak current of about 4,000A, so are robust enough to take the welding pulse current.
Here's a pic of the capacitor bank and thyristor, all hooked up:
The welder needed a bit of work to sort out an electrode holder and a box to hold all the bits, plus I had to make a suitable adjustable power supply to charge up the capacitors. Here are a couple of pics of the finished Mk1 welder:
I'm currently making up battery housings and sorting out the best place to mount the controller (an Alltrax AXE4834). I'll post an update as I get things sorted.
Hope this stuff is of interest!
Jeremy
I spent the first six weeks getting the frame and parts bead blasted and painted, rebuilding the front forks, brakes and wheel bearings and generally getting the thing to the rolling frame stage.
Next up was the fitting of a Mars Electric LLC ME0709 motor, which turned out to be pretty easy. BTW, I'd highly recommend John Fiorenza at Mars if anyone is after a motor in this power range (up to 72V, around 150A max). He's a great guy to deal with and went out of his way to sort a shipping problem for me very quickly. The pictures below show progress on the bike so far:
The next challenge was to get some suitable batteries. I opted to use 64 off Headway 38120 10Ah LiFePO4 cells, wired as a 16S, 4P pack. Having put my faith in the ability of banks to transfer large sums of money around the globe, I was comforted to find that a very large box of cells arrived all the way from China just a few days after placing the order. Here they are, just as I opened the box:
To make the battery pack up I needed to find a way of connecting these cells together. This meant building a capacitor discharge welder, to weld nickel tabs between the cells. Ebay was a useful source for 15 ex-computer power supply, 97,000uF, 20V, low ESR capacitors for a few pounds, plus a box of very large thyristors (I still have a few of these left over). The thyristors are good for a peak current of about 4,000A, so are robust enough to take the welding pulse current.
Here's a pic of the capacitor bank and thyristor, all hooked up:
The welder needed a bit of work to sort out an electrode holder and a box to hold all the bits, plus I had to make a suitable adjustable power supply to charge up the capacitors. Here are a couple of pics of the finished Mk1 welder:
I'm currently making up battery housings and sorting out the best place to mount the controller (an Alltrax AXE4834). I'll post an update as I get things sorted.
Hope this stuff is of interest!
Jeremy