GS500F Restomod Street Tracker

[SK Racing]

Been a lurker for a few years and decided to document the progress of my current project.

In February 2017 I acquired a 2004 GS500F in a barter transaction. The bike had been standing outside in the sun and rain for three years prior to landing in my garage. It wouldn't start and upon closer inspection, I found water in the fuel tank and float bowls. That was soon remedied and it started easily with the new battery that the previous owner had bought just a month before. The bike had done 23,400km since new, so fairly low mileage, but it had been dropped and I got it with scratched fairing and right hand engine cover.

The idea is to change this:




...into this:




Update Jan 2022: This is what it looks like now. Still some work to be done, but it is close to what I envisioned.
I've been riding it like this since May 2021 and get asked a lot of questions at shopping malls. Even offers to buy it. I'm also getting used to the strange turning behavior with those big tires. It felt totally wrong in the beginning, but I'm not sorry I put them on.

[SK Racing]

Mechanically, the bike was in surprisingly good condition. The plastic side covers and the scratched fairing were removed and after a few minor cosmetic repairs, the bike passed roadworthy at the first attempt in May 2017 and ownership was changed into my name.

While riding the bike for about 3,000km, various parts were replaced or upgraded as my budget allowed.

[SK Racing]

An imported stainless steel slip-on muffler was installed, together with K&N-style pod air filters and 145 main jets.



Performance improved only slightly, and the engine still had some hesitation round 7000 RPM, accompanied by excessive vibration. I stripped the carbs again and this time also opened up the top covers and saw that one diaphragm had been pinched by the cover. The diaphragm didn't seem to be damaged and I assembled the carbs again. Performance improved dramatically and the 7000 RPM hesitation as well as the vibration had gone away. The prognosis is that one cylinder wasn't working optimally due to the pinched diaphragm.

[SK Racing]

The front fairing was removed and I designed 3mm stainless steel brackets and had them laser cut to mount the LED headlight (also imported from China) directly to the triple tree. So too the front LED turn indicators, although I'm considering removing the latter and installing handlebar-end indicators which will hopefully also negate the need for rear indicators.

[SK Racing]

This is what the bike looked like for more than a year. I taped up the red and silver on the tank to get an idea of what a plain color would look like and the idea of the "nude look" grew on me as time went by.

[SK Racing]

The original handlebar was replaced with an off-road classic style handlebar. Emgo #23-924102.

I cut approx. 2cm off each end to get through traffic easier.

[SK Racing]

Being a frugal builder, I managed to locate and purchase at a bargain price, a virtually new Kenda Big Block tire (130-80/17) with almost no wear. It had only been on grass for a short distance. A similar new tire will be used for the rear. Before making the purchase, I had made very sure that the bulky tire will fit in the front fork, and it fits only just, with barely 2mm gap each side.

[SK Racing]

At this stage, I had decided to go for the "street tracker" style. That means the sub-frame will have to be modified in order to become a proper street tracker. I know it's a big task involving the making of a new custom seat as well. With the envisioned new sub-frame, the aim was to have an uncluttered under-seat area and therefore there would not be space for the bulky lead-acid battery.

After researching various options, I decided on a Lithium-Iron Phosphate battery. So, a 4-cell LiFePO₄ battery (meant for RC model planes) was purchased (the only one locally available in a reasonable Amp/hour capacity) and thicker cables were soldered on to handle the high starting amps. Compared to the standard Pb battery, this LiFePO₄ battery is minute, not only physically, but also capacity-wise at only 3.8 A/h. That's roughly a third of the capacity of the original 10 A/h battery, but it starts the engine with ease and I used it for about 3 months without any problems - until the sub-frame got modified, which was the last time I rode it.

[SK Racing]

A BMS (Battery Management System) was added to safeguard against overcharging and to ensure that the four cells are kept balanced at all times.

Since the engine is only 500cc, I opted for a 100Amp BMS and so far it has been working flawlessly. I've checked multiple times and the 4 cells stay in balance and the bike starts easily. Without the BMS, one cell tends to overcharge, so it's clear that a BMS is necessary.

This is the model that I bought, however from a different supplier (who is out of stock now):
https://www.ebay.com/itm/4S-100A-12-8V-w-Balance-LiFePo4-LiFe-18650-Battery-Cell-BMS-PCB-Protection-Board-/263385524359




Although I put heatshrink around the BMS, the ends are still open. I'll have to properly seal the ends to keep moisture out by liberally brushing on some conformal coating. (available at electronics shops, like Mouser, RS, etc.)

[SK Racing]

As we GS500 riders are painfully aware, the engine needs to be started on choke when cold, and invariably, it would stop running while you're in the house waiting for it to warm up. So, to prevent the headlight from draining the tiny battery when the engine stops running, I designed and built an electronic gadget to only let the headlight be on when the engine is running, and thus, charging the battery. The gadget gets its input from one phase of the alternator and is controlled by an ATTiny-85 microprocessor which allows setting the on and off voltage points precisely. Switching is done electronically via a MOSFET that can handle 30A. Since the headlight only draws 4A on high beam, no heatsink is required.

Another advantage of this "auto headlight switch" is that the headlight will stay off until 3 seconds (adjustable) after starting, which will help with cranking the engine in cold weather.

[cbrfxr67]

 Good stuff here!  Loving it!

[SK Racing]

Good stuff here!  Loving it!

Thanks cbr. There is still a lot of work to be done. 

[SK Racing]

I could already feel a handling difference after removing some unnecessary weight, like the center stand, fairings and heavy battery.

In December 2019, I took the bike to a local guy that does tig-welding (or was it mig? not sure) for construction of the new sub-frame. Working from CAD drawings I had made onto an overlay of a side view of a naked GS500F, he welded on a round tube sub-frame that I'm mostly happy with. There are always compromises in projects and this case was no exception. But I think the bike will turn out almost as planned.

I can already feel a handling difference after removing some unnecessary weight, like the center stand, fairings, rear footrest brackets, bulky battery, etc.

[ShowBizWolf]

I totally agree with cbr... great pics and thread! I enjoy seeing this kind of stuff. Thank you for sharing and I'm looking forward to more.

[SK Racing]

Thanks for stopping by, ShowBiz. And thanks for the compliment. Your own thread and also those of many others have been a real inspiration on my journey with the GS so far.

[SK Racing]

Some of the stuff that I ordered from China got stuck in Hong Kong during the strikes there last year (2019). The parcel contains new smaller speedo and tacho, handlebar grips and levers, as well as handlebar switches.

Fortunately, in a previous order, I received an LED taillight which fits very neatly under the rear hoop. I needed to have the taillight in my hands while designing and making the rear hoop to ensure that its a good fit.

[SK Racing]

The next step is to sand  the sub-frame down and paint it.

But in January 2020 my back started acting up and I had to undergo spinal surgery in February. That ended my ability to work on the bike for the time being, but I'm hoping to resume the project in a few months. Typical recovery time is anything from six months to a year. In the meantime, since I'm able to sit behind a computer screen, I have decided to post about my GS500 Restomod build on GSTwins. Need to keep motivated... 

Expect updates as and when it happens.

[IdaSuzi]

Hey your build looks great! I also like the flat look on the tank and I am going to be painting my tank this summer, once it finally warms up here in the frozen north. Keep up the good work, and hope you have a swift, complete recovery!

[SK Racing]

Thanks for the compliment and good wishes, IdaSuzi. I'm taking it one day at a time. So far there has been a steady improvement with my back. At least I can walk again. It's just difficult to bend over to do some work on the bike for instance. But I'll get there.

What color are you thinking of making the tank? I'm leaning towards blue for safety. A black bike is not very visible on the road.

Seeing that I'm restoring the bike as well as modifying it, I've been gathering information on how to replate nuts, bolts and other small parts. Nickel plating seems the way to go. If anyone has experience with DIY nickel plating, I'd like to know your opinion on how successful it can be done at home. I've stumbled upon this blog and it seems quite easy to do: http://yamaha-ls3.blogspot.com/2015/02/diy-nickel-plating-bolts-and-nuts.html

[Endopotential]

Welcome to the club!

I think our bikes share a few design cues and random pieces 

So cool to see fellow GS owners from around the world.

Your auto headlight switch is brilliant.  Looks like you've got plenty of electronics know-how!