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[buildsix]

Hi everyone

I just joined the forum today after checking out some of the other posts.

I started building an EV conversion recently using a 1981 KZ440 LTD cafe racer as a donor and have made some decent progress over the last few weeks. The drive system is now together and on the bench and I’m about to start the 12v wiring and the battery box fabrication. Just wanted to share what I’ve done so far as I’ve gone through a bit of pain in some areas and it may help other builders, plus I’ll have more questions so hoping to tap into some knowledge.

Overview for the conversion:
-1981 kz440 ltd with ktm duke 390 front end
-Custom adapted duke 390 brakes
-17” 8kw QS hub motor driven by a Kelly Controller
-24s NMC lipo pack @ 7.4kWh
-Thunderstruck tsm2500 charger with dilithium MCU, BMS and SOC meter
-Vicor 400W switch mode dc-dc converter
-8Ah antigravity 12v battery
-Motogadget mo.unit blue
-Motogadget motoscope pro

EST weight at ~140kg





I also put some videos together for the build if anyone is interested in checking them out. I ended up doing something a bit different with the drivetrain power so it may be of interest to some. The videos are a bit cringy as it’s my first attempt at anything like this so excuse the bad acting and terrible voiceover

[TheRan]

Mate, that was very enjoyable to watch, don't know why you were selling yourself short. Usually the mention of cafe racer alone puts me off but that's because most of them are very poorly done, but your quality of work and the thought and effort put into it is very impressive and far beyond what I was expecting. I've subscribed because I'm really interested in seeing the rest of your work and this thing completed.

[buildsix]

Mate, that was very enjoyable to watch, don't know why you were selling yourself short. Usually the mention of cafe racer alone puts me off but that's because most of them are very poorly done, but your quality of work and the thought and effort put into it is very impressive and far beyond what I was expecting. I've subscribed because I'm really interested in seeing the rest of your work and this thing completed.

Thanks for the kind words and the sub! Glad you enjoyed the videos too, they are a lot of fun to make - and hopefully also help others doing similar projects. Really looking forward to getting this thing together to start road testing.

[TheRan]

Honestly, with the quality of the video production and the way you present I would never have thought you'd only been doing this a few months and had 30 odd subscribers. Hopefully that number goes up steadily, with the effort you put in you deserve it and more people should see it. I'm glad you're going through the effort to get it road legal too so it can really be enjoyed.

[buildsix]

Honestly, with the quality of the video production and the way you present I would never have thought you'd only been doing this a few months and had 30 odd subscribers. Hopefully that number goes up steadily, with the effort you put in you deserve it and more people should see it. I'm glad you're going through the effort to get it road legal too so it can really be enjoyed.

Thanks again, that's really motivating RE the videos. A road legal EV conversion is something i'd been wanting to do for years and finally decided to try it since the cost of suitable batteries is now workable.

[Specter]

For those looking for cheap batteries.   I often get a LOT of decent/ read really good condition batteries from places like the Batteries Plus stores.  Hospitals and other critical demand places have to change their batteries out on their Defibrulators / Cardiac maches and other critical equipment every few years at most, whether it's good or not, CHANGE IT.  They take the batteries to these stores to get rid of them.  So you have access to lightly used, WELL taken care of Lithium batteries, for essentially free.

They don't always have the LiPo's but DO have a lot of higher ampere hour demand Ferro chemistries, so unless you need a ton of amps for the bike for blistering speed, one of these might work super well for you also and are typically rated for stupid like 5 to 8 k cycles from the manu.

Just talking out loud, might help you find batteries if you need to get some to play with / test your bikes with.   Invariably they get boogered up every now and then, and it's nice to have a source of cheap replacements.

Aaron

[CagivaRider]

In the winter of 1986 I  built a TZ500KX - a TZ250 road racer chassis with a Kawasaki KX500 two stroke 500cc motocross motor. It raced in the Pacific Northwest road racing series in the open single class. I raced it and won several regional championships in British Columbia, Washington State and Oregon. I wish I had the design tools we see here. It would have been even better than it turned. I am so impressed with your project and how thorough you are! I am glued to your channel.

Thank you for sharing.

[buildsix]

In the winter of 1986 I  built a TZ500KZ - a TZ250 road racer chassis with a Kawasaki KX500 two stroke 500cc motocross motor. It raced in the Pacific Northwest road racing series in the open single class. I raced it and won several regional championships in British Columbia, Washington State and Oregon. I wish I had the design tools we see here. It would have been even better than it turned. I am so impressed with your project and how thorough you are! I am glued to your channel.

Thank you for sharing.

Your build sounds like a lot of fun. I've never ridden a 500CC 2 stroke but can imagine how that would have gone

CAD and 3d printing and prototyping services have certainly made one off builds a lot more accessible for DIYers with a basic home shop. Thanks for the sub!

[buildsix]

For those looking for cheap batteries.   I often get a LOT of decent/ read really good condition batteries from places like the Batteries Plus stores.  Hospitals and other critical demand places have to change their batteries out on their Defibrulators / Cardiac maches and other critical equipment every few years at most, whether it's good or not, CHANGE IT.  They take the batteries to these stores to get rid of them.  So you have access to lightly used, WELL taken care of Lithium batteries, for essentially free.

They don't always have the LiPo's but DO have a lot of higher ampere hour demand Ferro chemistries, so unless you need a ton of amps for the bike for blistering speed, one of these might work super well for you also and are typically rated for stupid like 5 to 8 k cycles from the manu.

Just talking out loud, might help you find batteries if you need to get some to play with / test your bikes with.   Invariably they get boogered up every now and then, and it's nice to have a source of cheap replacements.

Aaron

Thanks for the info. This is an interesting option that I never knew existed. The challenge may be getting enough cells of a similar type/size to make larger packs that can be balanced. That said, if they are consistently "lifed" then its likely that cells of the same type would have similar remaining performance. If the price is right and you are able to match a stack of them up then this could work really well.

[Specter]

Some of the throw aways I have gotten are your 30 and 40 Amp hour batteries, so they have a decent amount of cells in them.  The hospitals change them all out pretty much in a group, so realistically, even though you may have to tear apart 4 batteries to make 1 bigger battery, all the cells, are probably about the same in the amount of use they each received. 
Ive talked to the techs who actually did the change outs at the hospitals, and he was saying that many of the batteries, the system is on the grid, the battery is just in case it went down, the hospitals also have emergency generators too, so IN the rare case it was used, it was only for a minute or so, so they are all essentially like brand new, but the ins company makes them change them out for liability reasons, so out they go !

Hey Aaron, do you want a pallet load of 33 Ah Lithium Batteries, each one has it's own built in BMS.  Max amp draw per battery is 40 amp.  F-K yeah Ill take that!!!  Lead acid recycles,  Lith FerroPhosphate does not, they are more than happy that I take these off their hands.  Worse case, drain them chop them and chunk em, Ill recycle the nickle for a few bucks / lb.

Aaron