Yamaha xs400 qs180 conversion

[Wheelsandall]

I’ve owned my 1981 xs400 for at least 20 years and it means alot to me being my first bike. We’ve been through a lot but for the last few years it’s just been sitting. It ran fine. Could do 80 downhill and would need yet another carburetor rebuild if I was going to get it going again. I decided it needed an upgrade. I started doing reasearch and found the qs180 to be more than enough for what I’m looking for. I wanted to avoid the “easy” route of a hub motor so I started looking. I found a qs180, FarDriver 961800, display, wiring harness throttle and other small parts for $1480 shipped from alibaba. I ordered it an on the slow boat from China it came, about a month later. I planned on using 4 Honda 12s (24s2p) clarity batteries but when I built the frame it was very clear only two would fit. This only gives me 25ah. I plan on doing a saddle bag type of deal for the other two after I get it going. So far the motor is mounted with custom brackets and the battery tray is made. I’ll get more pics tomorrow. I’ll try to keep it updated as I go.

 

[Wheelsandall]

Well this wasn’t the original plan but since they technically fits it will have to do for now. Here’s the battery tray and rough layout.

 

[j bjork]

Wouldn't it be possible to have two modules standing in front of the motor, then two laing down behind them?
Like the one you have on top now, but behind the two standing up.

 

[Wheelsandall]

I see what you’re saying. Unfortunately the two in the front would leave no room for the ones in the back to line up.

 

[Wheelsandall]

It’s not ideal nor how I thought it would look. It they’re mounted. Using standoffs to keep them from touching. Or laying on the frame. This also gives me space for the leg rests.

 

[rob1981]

awesome @@!!!!!!

 

[Wheelsandall]

The BMS, precharge circuit and main contactor are mounted to some leftover plastic stock which fit in the opening above the batteries.

 

[Wheelsandall]

Got the FarDriver controller mounted Eve though it’s enormous, it fit nicely under the seat after I welded a bracket to the frame for it. Just some more wiring and we’ll see if it runs.

 

[Wheelsandall]

Got everything wired up the bare minimum to run and it’s alive! Had a good scare when it kept setting an encoder error message. Had to change the encoder model and thankfully that fixed it. I got most of the 12v stuff wired up. I had planned on just leaving the original harness and tapping the 12v converter directly to the original fusebox but I decided to just rip the original harness out and use the supplies one and just run the required wiring. One thing I strongly suggest is replacing the 22 gauge main 12v power and ground wires with something thicker and a better fuse holder. These Chinese harnesses are notorious for cheap wiring.

I still need to get a sprocket on it and figure out gearing. Then onto figuring out bodywork because it looks like a robot exploded all over it

 

[SlowCo]

Very nice project. Will follow your progress to see how it will turn out when 'finished' and how it will perform.

 

[pwd]

Looks like a fun build so far. Looks like aptly sized motor + controller + battery current for that bike. What sized sprockets will you use?

 

[Wheelsandall]

Currently it’s the stock sprocket in the rear and a the smallest I could find is a 12t sprocket for the front. I’m sure these will be too tall but I have to do some research to find out what sprockets can fit on the back. There’s only two sizes for the stock xs400 which is like 37 and 39. May have to modify something from another bike. Apparently the qs180 has a weird shaft size. It’s 20mm but the splines are different than most. I had to dremel the splines down 1mm each on the Amazon sprocket to fit.

 

[pwd]

If you haven't already seen this site; it has a good cross reference for sprockets that may help you find other models with the same offset and bolt pattern etc... JT Sprockets: Catalogue

 

[Wheelsandall]

I got all the lights wired. I wired the precharge relay to the oil light so when the precharge contactor comes on it lights then goes out when the main kicks in so you know when you’re ready to go. Also made a bracket for the display included in the kit and wired the turn signals and high beam indicator into it. It’s pretty cool the display turns from white to black when you switch the high beams on. I can’t find any info on this display but it has a usb port so idk if it’s programmable.

I kept the original analog speedometer on it for a nostalgic look. It runs on the front wheel so it will still keep speed and more importantly the odometer.

I’m trying something a little different. I’m using the clutch lever as the motor cut/regen. This leaves the front and rear brakes as they are. I cut the original cable down and put a spring on the end and am using the clutch switch as the low brake input to the co troller.

 

[Wheelsandall]

If you haven't already seen this site; it has a good cross reference for sprockets that may help you find other models with the same offset and bolt pattern etc... JT Sprockets: Catalogue

Awesome. Thank you! I used it to find that an xs250 had a 43t sprocket which is at least more than my 37. I’ll looks for one of them.

 

[bananu7]

Why do you assume it's gonna be too tall? 12:37 is 2.67 reduction. At 5000 motor RPM and ~2m wheel circumference that gives 192km/h, about right for a top speed. I guess with 24s you can spin it a bit faster with FW, but not all that much faster. It should be plenty strong from the start regardless, so the more important metric for target cruise rpm would probably be the efficiency peak.

 

[Wheelsandall]

Thank you for the math. I try to do that in my head and it just hurts. I’m certainly going to try it as is and thanks for the motivation. I’m waiting on the chain now. Should be today.

 

[Wheelsandall]

While I’m waiting on the chain I’m finishing up some wiring and programming the display. As I said there are no instructions with the display but after a Google image search I found it. It has 2 connections that I couldnt figure out. Apparently this display has a built in radio/ Bluetooth and those are for speakers! Also I’m assuming the usb is an input for an iPod or something but I’ll use it for charging. I don’t know if I’ll be listening to tunes while I’m riding but maybe I’ll just blast some Harley sounds out to freak out the Harley guys.

 

[dominik h]

12t will kill your chain very fast and it will make a lot of noise.
I would at least take 15t and there exist companies that makes the rear one like you order it.
I would gear it lower, that gives you more tourque and will generate less heat.
Start with what you can get for cheap and reeuse your existing chain and change it later to your needs.

 

[CRF265]

Hmmm... some conflicting advice here...
My 2c. Take it or leave it..

I think the reality is that you will need to accept faster chain wear as there is no jackshaft reduction.

2.67 is waaaay to tall and will be very sluggish requiring phase amps saturation to get up and go from a stop. High controller heat, inefficient motor range, no grunt and higher wh/km.

I'd be going the lowest gearing you could possibly fit. Like 10t front 48t rear. 4.8 reduction will sit on 4000rpm at 100kph which is the efficient sweet spot and will still have a max speed of around 140kph if you push it to 5600rpm. It takes alot of power to actually push a bike faster than that and is not worth the sacrifice in low end. Its an increase of 1.8x the torque of your current gearing and would be a massive improvement and the minimum reduction i think you would need for the road.

Or get a custom 58t rear as suggested and stick with the 12t. Less noisey and would wear a bit better.

 

[Wheelsandall]

It’s alive! It’s definitely sluggish off the line like you guys said. I got it up to 60mph and it’s still pulling. The front brakes aren’t working so I figured I won’t go past that, you know cause brakes are important. Everything for the most part is staying cool. The controller is gettin warm to the touch but it’s also 100 degrees out. The display isn’t reading speed or rpm. Maybe it’s mad I switched it from kph to mph. Still have to modify to gas tank to get it to fit and some other small stuff but gearing is most important right now. The chain is a little noisy but it’s also a cheap Amazon chain because I’m not going to butcher a new one until I know what gearing I’m using.

 

[harrisonpatm]

It’s alive! It’s definitely sluggish off the line like you guys said. I got it up to 60mph and it’s still pulling. The front brakes aren’t working so I figured I won’t go past that, you know cause brakes are important. Everything for the most part is staying cool. The controller is gettin warm to the touch but it’s also 100 degrees out. The display isn’t reading speed or rpm. Maybe it’s mad I switched it from kph to mph. Still have to modify to gas tank to get it to fit and some other small stuff but gearing is most important right now. The chain is a little noisy but it’s also a cheap Amazon chain because I’m not going to butcher a new one until I know what gearing I’m using. View attachment 390077

Looks good. I know you're going to add coverings and tidy it up, but for now the naked electric look is really neat

 

[Wheelsandall]

Looks good. I know you're going to add coverings and tidy it up, but for now the naked electric look is really neat

Thank you. I’m gonna leave some of it exposed. Probably a decent amount. I still need to cut the tank down and cover the electronics. Then I’ll take a step back see what I want to do from there

 

[Wheelsandall]

after searching literally every sprocket on jt sprocket’s website I found on that’s close enough even though it will still have to be modified. It’s 47t. I also ordered a 10t and 11t front sprocket. I really don’t like the 10t since it’s too small to even use a bolt on retainer, just a c clip but we’ll see how it goes.