Light dirt bike, QS 120 70h motor, custom steel frame

Chambers said:
Looking good,

Can I ask why you are not running the motor concentric to the pivot anymore? Was there an issue with it or something else?

Thanks
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well the old motor (BHT) was small enough to fit between the pivots. it was an attempt at compartmentalization so i could treat the drivetrain+swingarm as separate. this being my first ever frame design as well as first ever serious welding project

did some welding today:


IMG_20200506_135930.jpg


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Overclocker said:
well the old motor (BHT) was small enough to fit between the pivots. it was an attempt at compartmentalization so i could treat the drivetrain+swingarm as separate. this being my first ever frame design as well as first ever serious welding project
did some welding today:


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Look at you stacking dimes. Really nice welding. Those welds look like they where done by a professional. Cool Cool.
This is gonna be a wicked one when completed.
 
Looking good man! Are you going to run a tensioner now?

Is that the Pirelli vintage dirt bike moped tires 17"? i think i just bought two of those

That QS motor doesn't look so huge now that its in the frame, a few other threads are using these motors in actual dirt bikes that are likely 100lbs heavier than this build, if they are having good results yours should be excellent!
 
skeetab5780 said:
Looking good man! Are you going to run a tensioner now?

Is that the Pirelli vintage dirt bike moped tires 17"? i think i just bought two of those

That QS motor doesn't look so huge now that its in the frame, a few other threads are using these motors in actual dirt bikes that are likely 100lbs heavier than this build, if they are having good results yours should be excellent!
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yeah i think i need a chain guide AND tensioner. and maybe a slider over that crossmember that's clanking in the video

this tire is copy of the trail wing (tw27 ???). unimaginatively named "wing 2000" :lol: made by a local tire factory here in philippines

btw this motor is the 120 70h. the smaller less popular brother of the 138 70h (there's also the 138 90h i mentioned via PM). i don't think there are very many DIY builds using this motor. on youtube there's just one, a really tiny pit bike.


IMG_20200509_145556.jpg
 
Oh that makes sense, its the 2000w version...I was a little confused for a minute there wondering how that thing powers full moto's since that is what i'm trying to do right now for a side project

Tire looks very similar to the old vintage pirelli's i just picked up on fleabay, i wish i had a more aggressive tire on my Kuberg

chain tensioners, not super ideal but helps(same with my Kuberg). this is where the Sur-ron and Motoped shine, but don't tell them i said that! Waiting to see the first ride vid of this sweet motor!
 
IMG_20200515_101550.jpg



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so here's the complete frame w/ the motor mount. 8.48kg weight. not that much heavier than the surron's but not exactly a fair comparison. the surron saddle subframe seems to be included in that weight figure. but still i guess i made the right choices w/ my wall thicknesses. i don't claim that this frame is as strong...



skeetab5780 said:
Oh that makes sense, its the 2000w version...I was a little confused for a minute there wondering how that thing powers full moto's since that is what i'm trying to do right now for a side project

Tire looks very similar to the old vintage pirelli's i just picked up on fleabay, i wish i had a more aggressive tire on my Kuberg

chain tensioners, not super ideal but helps(same with my Kuberg). this is where the Sur-ron and Motoped shine, but don't tell them i said that! Waiting to see the first ride vid of this sweet motor!
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rol.jpg



still deciding where to put my roller/tensioner...
 
IMG_20200529_105004.jpg



- battery packs got moved up slightly
- slightly longer swingarm w/ slightly higher leverage ratio to better utilize the entire stroke of the shock


still need to redo my saddle struts and paint the frame bright yellow/green like the decal on the fork. swingarm and struts would be silver or gray

PS i love how everything fit so neatly inside the frame
 
Any review on the qs and the votol yet? How does it compare to the bht? It certainly looks cooler!
 
skeetab5780 said:
Any review on the qs and the votol yet? How does it compare to the bht? It certainly looks cooler!
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i've set the votol to 80a for now to match the 80a of my previous setup (ykz7280 + bht)

same gearing at well. 11t x 53t

QS+votol pulls much harder at the same 80a. very noticeable. higher top speed as well 80kph. bht+ykz only did 60kph

definitely worth it
 
How well setup is the Votol when purchased with a motor? Does it require that you learn how to program it or is decently rideable from the start.

I ask because I would ultimately want a Nucular to
Pair with a qs but given the wait time and the low price of the Votol it would be a nice temporary solution if there isnt a steep learning curve.

Also, excellent work on the frame. How did you figure out the general size and dimensions when you started this project? Ive been wondering a lot lately about the size difference between light e-moto vs full size dirt bike. Seems like most of the e dirt bikes on the market are mini like sur-ron, oset, kuberg, etc. People seem to love them but I'm left wondering why even light bikes arent the size of a full grown MX bike. Is the size of gas MX race bikes a product of necessity in terms of packaging and supporting the motor and cooling systems or do larger bikes handle better?

What was your thought process when you started relating to overall size?
 
DanGT86 said:
How well setup is the Votol when purchased with a motor? Does it require that you learn how to program it or is decently rideable from the start.

I ask because I would ultimately want a Nucular to
Pair with a qs but given the wait time and the low price of the Votol it would be a nice temporary solution if there isnt a steep learning curve.

Also, excellent work on the frame. How did you figure out the general size and dimensions when you started this project? Ive been wondering a lot lately about the size difference between light e-moto vs full size dirt bike. Seems like most of the e dirt bikes on the market are mini like sur-ron, oset, kuberg, etc. People seem to love them but I'm left wondering why even light bikes arent the size of a full grown MX bike. Is the size of gas MX race bikes a product of necessity in terms of packaging and supporting the motor and cooling systems or do larger bikes handle better?

What was your thought process when you started relating to overall size?
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my votol arrived in some kind of "park mode" and woudln't even spin the motor. needed some very obscure settings that you'll never figure out w/o reading through that long votol thread

then the config program is very buggy. erratic results w/ certain combinations of values

but if you get it to work it's great. low cost. nice flat size. nice throttle response and curve w/ plenty of control at low speed. regen responds nicely (not variable though). flux weakening

as for size well if you want lightweight then you want a DH fork but overall size of bike is constrained coz there are no DH forks longer than 203mm travel. you can't build a full-size using a little DH fork.

i'm 5'11" btw the bike really is a bit small. my wheelbase is already a bit longer than surron


81549314_569331696982211_3845063669243183104_o (Medium).jpg
 
It hadn't occurred to me that the fork length dictates the overall dimensions but that makes perfect sense.

The issues you had with the Votol sound frustrating. Thats the kind of thing I was afraid of. Sounds like you got through it. I like tinkering with stuff but I get so little free time to work on bikes these days that I hate the thought of spending 100 hours trying to trick hardware into working instead of being able to ride. The price is attractive though.
 
The bike looks great. Any footage of the bike in action? It would be good to get an idea of the performance of that motor and controller setup.
 
Craigh85 said:
The bike looks great. Any footage of the bike in action? It would be good to get an idea of the performance of that motor and controller setup.
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will post one soon. i just finished the upgrade to 428 (from 420). minimal weight increase as long as you use 428 chain not the heavy-duty version 428H. while i was at it i got the largest off-the-shelf sprocket (56t) as well as the smallest (10t)

[youtube]pySFgenstXg[/youtube]
 
DanGT86 said:
Looks great! That's my favorite color other than black! You should paint the swing-arm too.
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yeah it's my favorite "bright" color too. for some reason bright orange seems to look old the longer you look at it

btw the color scheme reminds me of my Ryobi power tools. i'm tempted to put red RYOBI logos on the battery sides :lol:
 
Looking good man! I also bought the Votol 100 have not had the chance to put it in yet!
 
[youtube]9JjLhp5uX6w[/youtube]

improved the time a bit. but the start wasn't good. i was fully leaned forward but the front tire was still lifting


skeetab5780 said:
Looking good man! I also bought the Votol 100 have not had the chance to put it in yet!
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votol is pretty good. just buggy :lol:

btw when i got mine it was in some kind of "park mode" and wouldn't even run
 
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