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Discussion Starter #1
Had an old engine, frame and swing arm I thought I'd make use of, going to reinforce the frame as its probably made of cheese, recently picked up a set of forks, wheels and plastics cheap and will slowly turn this into a roller.. Eventually i'm planning on converting to electric, using a qsmotor 120 70h mid drive motor, hopefully running approx 10kw of power.

How it sits at the moment with 10" wheels, waiting on 310mm shock, forks are 660mm, I've also modded to fit crf70 plastics


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Discussion Starter #2
Excuse the self taught noob welds!

This is where I have braced so far... not sure whether to add more underneath the top tube as well?

May also brace the rear A frame as well

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70 plastics look so much better with extended swingarms on 50s. Keep on building.
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Discussion Starter #4
70 plastics look so much better with extended swingarms on 50s. Keep on building.

They sure do! That thing looks insane!!

Is that on 10/12 or 12/14 wheels? Do you know what length forks you have? I really dig that!

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10/12. 730mm. The frame is really tall and needs the long forks.
 

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Discussion Starter #6
10/12. 730mm. The frame is really tall and needs the long forks.
Ah I thought they looked quite long, looks like a great set up and geometry though!


Got some bits done recently, rear shock and rear brake mounted.

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Had a look at the doner engine I had and soon found out what was wrong with it, not entirely sure how the entire valve seat has pulled out?? either way picked up an entire new cylinder head dirt cheap as its just an old small valve 125 engine.
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How its sitting at the moment, pretty happy with it, the shock sag is a little on the stiff side for my weight at the moment and will adjust soon.
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Discussion Starter #7
Bars came today, also mounted the exhaust, making use of some old ktm end can, I think it was actually from a 2 stroke despite looking like a 4 stroke muffler..
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Discussion Starter #8 (Edited)
Was looking at the footpeg position and think of moving the foot bar further back, basically mounting the front two bolts on the rear two holes under the engine (this frame doesn't have a cradle and thinking of making one so I could easily adapt it) but wondering if anyone has done anything similar? I feel moving them back a touch will have a better riding position..



Wrapped the header as its only a cheap chromed one and will turn to rust in 5 seconds, never actually wrapped one before, Its an old wrap as well..

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Front brake fitted, the caliper needed a bit of material ground off the back as I presume it is more suited for 14" wheel as it was rubbing on the rim of the 10" front wheel.
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That's a fun looking toy!

The only thing that is odd is that the front fender looks massive on that small tire.
 

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Discussion Starter #10
That's a fun looking toy!

The only thing that is odd is that the front fender looks massive on that small tire.
Thanks bud!
Haha yeah it is a bit disproportionate but should catch dirt and wet faaar better than a crf50 fender!


Tried the engine for the first time yesterday and seems to run great and seems to have plenty of compression with the new head, although it does seem pretty wimpy to me, maybe its just all a small valve 125 can offer?

Also the clutch seems incredibly light on the lever but after riding it about it doesn't seem to be slipping at all so may just replace the clutch unless anyone knows if these clutches are often very light to pull? Would a clutch become easier to pull as it wears over time?

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You mentioned the header will rust and you wrapped it. If you were wrapping it thinking it will prevent rust you may need to reconsider bc the wrap actually speeds up the rusting process as it holds moisture causing the reaction to occur much quicker.

The cheap 125s are pretty wimpy in my experience, not much better than a crf70 or 50 with a 88 big bore and stock head, they just have more torque

Looks like a fun little bike though.
 

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Discussion Starter #12
You mentioned the header will rust and you wrapped it. If you were wrapping it thinking it will prevent rust you may need to reconsider bc the wrap actually speeds up the rusting process as it holds moisture causing the reaction to occur much quicker.

The cheap 125s are pretty wimpy in my experience, not much better than a crf70 or 50 with a 88 big bore and stock head, they just have more torque

Looks like a fun little bike though.

Cheers!
yeah I know it wont stop the rust, only there to hide it haha. Ah well for a $30 engine it will do for now until I start the electric conversion!

Here's the motor for any interest.. approx 46 nm at the output shaft, motor weighs 8kg and should offer roughly 15kw / 19hp but im unlikely to run it this extreme due to battery life!

Ignore the fact the motor is listed as "2000w" this company for some reason MASSIVELY under rates their motors. they also have a "3000w" version which other people are pushing to 20kw

 

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Discussion Starter #14 (Edited)
welp, its happening, motor and controller came far sooner than expected in just 12 days! I was expecting 30+

Lipo batteries should be here soon, I was going to wait to test the motor before mounting but mounting the motor is pretty easy just some small brackets needed..

Motor and controller weigh approx 10kg, motor comes with a 20mm shaft for 420/428 sprockets.

Lipo batteries will weigh approx 7.8kg

Should be capable of up to 15kw/20hp bursts with the stock controller!



Still had a couple of rips with the 125 engine before hand..

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IMG_20191111_180216752.jpg IMG_20191112_193505836resize.jpg IMG_20191112_193949448.jpg IMG_20191104_145857618_PORTRAIT.jpg
 

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I really like this idea. I really wanted Alta to do well but pitbikes may be a better application of this type of tech as they can be used in backyards without annoying neighbors. Looking forward to seeing the progress.
 

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Awesome!! I'm thinking about doing the same with one of my z50s.

Here is a gokart I did with 50v lipo 400a controller and 1hp motor.
 

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I have zero interest in any electric vehicle, but I love engineering and ingenuity. I'm anxious to see this project working!
 

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Discussion Starter #18
I really like this idea. I really wanted Alta to do well but pitbikes may be a better application of this type of tech as they can be used in backyards without annoying neighbors. Looking forward to seeing the progress.
I thought about converting a full size bike for a long time and may well do in the future as the same ev motor company sells other motors perfect for bigger bikes at a great price but for now being my first electric conversion I thought I'd scale it down a bit and make it a bit cheaper too.
There is a company called OSET and they make a crf50 sized electric bike called the mx-10 aimed at adults

thanks!

Awesome!! I'm thinking about doing the same with one of my z50s.

Here is a gokart I did with 50v lipo 400a controller and 1hp motor.
I'd love to see that! that kart looks great fun haha!

I have zero interest in any electric vehicle, but I love engineering and ingenuity. I'm anxious to see this project working!
Thanks! I never used to myself and due to current battery tech its still not perfect but the batteries on offer today can still offer a lot of fun, riding where I live is quite difficult so having something quiet to bash about on locally would be great fun.

I'f you ever get a chance to try an electric bike or other vehicle, you definitely should! max torque at 0 rpm is very addictive
 

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Yea there
I thought about converting a full size bike for a long time and may well do in the future as the same ev motor company sells other motors perfect for bigger bikes at a great price but for now being my first electric conversion I thought I'd scale it down a bit and make it a bit cheaper too.
There is a company called OSET and they make a crf50 sized electric bike called the mx-10 aimed at adults

thanks!
Yea the problem for us in the states is there are no importers of electric minibikes really. Most of the the ones I have seen are in Europe and Austrailia so the DIY idea is a good option for people like me where I have no problem fabricating.
 

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Yea there


Yea the problem for us in the states is there are no importers of electric minibikes really. Most of the the ones I have seen are in Europe and Austrailia so the DIY idea is a good option for people like me where I have no problem fabricating.
Get on Craigslist and pick up a razor mx500 or 650. Then buy a brushless 1800w motor package for 120$ on eBay.
 
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