Tom's mini dirt bike build thread

[nonlineartom]

Picked up a 200W kids electric dirt bike, called the Mongoose here in the UK, really solid steel frame, 9ah SLA's, 200W brushed Currie motor, 20" wheels with 2.25 tires and a front disk. It says "up to 11 years" but I'm within the weight limit for the bike and it's bigger than a BMX. Here is what it looked like when I got it (cheap off eBay)

First job was to strip off all the plastic tat and measure up. Good news is my 36V 15ah A123 pack fits nicely into the frame where the old SLA's go, I'll probably make an aluminium box for it to go in and weather proof it.

The brushed geared motor is.... disappointing, it gets to 13mph and can do hills, but it's underwhelming, plan so far is to go for the 960W Cyclone motor with an infineon controller tucked under the seat. Build a new back wheel using a Nexus hub and very strong BMX spokes and rim. I plan to fit a longer shock absorber on the back and 26" DH forks on the front, this should raise up up higher to give a bit more ground clearance. I'm in the process of cleaning and de-stickering the plastic to spray chalkboard black. Once the bike is complete then I'll look to strip and powder coat the frame. Yes, it's a poor mans mini stealth bike. Wish me luck!

P.S if anyone wants to chime in with words of wisdom, I'm all ears.

 

[TylerDurden]

http://www.evalbum.com/1709

http://www.evalbum.com/1363

Edit: removed landmine. ES remains independent.

 

[nonlineartom]

Thank you this is great! Looks like others had the same idea, nothing is original I guess. I've found a dealer of cyclones local to me that is going to sort me out with the right kit. Does anyone know what seat both of these are using?

 

[Thud]

Looks like a seat off a Yamaha YZ125
Those are before & after pictures form a member in canada. (top one is after with a monster Agni motor in it)

 

[TylerDurden]

First pic is BlackArrow's

Second is Denise E's:

Denise Eckert 2006 Mongoose CX450
"Modified CX 450 mid sized MX bike with hydraulic long travel suspension added( 8 inches front and rear) as well as hydraulic front disc brake, YZ 125 seat,pedaling system removed with pedals made parallel and locked, headlight, taillight and speedo added.
seat height raised to 30 inches by relocating rear shock and installing downhill mountain bike front forks( comfortable for an adult)"

 

[nonlineartom]

Missed that bit thanks. Don't think I'll take things quite as far as either of these folks but I'm guessing the 1200W cyclone will add a bit of kick for a fun ride. Just hope it doesnt kill my A123 pack :S

 

[Ariane]

Hi Thud,

The version with the Agni 95 R is this one, I really miss this electric motorcycle , is the same original frame but 10" longer, indeed both ebike use a Yamaha YZ 125 seat.

Good day!
Black Arrow

 

[Hillhater]

Ha, ! .. i posted last week, ..
..a brand new (boxed) one of these bikes just sold in the local Ebay for $207.50

 

[nonlineartom]

If only this was 50% bigger!

I've ordered an 8" shock absorber from a pit bike to replace the stock 5" shock which should give it some height. I'd love to stretch it by 10" but that might have to be for version2. My welding skills are a bit sub-par.

Can anyone tell me if the cyclone 48V 1200W kit will run alright at 36V? I'm probably going to go with a 15ah 48V liFePo4 pack in the frame when funds allow but would like to use my 36V rucksack pack in the meantime.

 

[Whiplash]

I WISH I could find one of these around here! I looked, but I guess they stopped making them a long time ago...

 

[EVTodd]

Looking forward to this build. I have always kept my eyes open on Craigslist for one of these too. I think it would be a fun toy.

After seeing some of the crazy builds using these bikes as a base I've always wondered how well they're holding up. I assume the frames are mild steel instead of chromoly?

 

[Whiplash]

Most likely, I would probably lengthen the swinarm so I could get a 26" rim on there, then run a triple crown fork with a sick R?C drive for power. Run it through a gear cluster in the rear for true electric dirtbike performance, WITH PEDALS so you could ride home after the fun! I bet you could get at least a KWH in the box as well so range would be good!

 

[nonlineartom]

I was just going to lengthen the frame up where the battery fits rather than at the swing arm, 20" wheels look like more fun than 26" wheels. I plan to fit a Nexus hub gearbox on the back wheel ( if I can find one ) so I can go for low speed / high torque and visa versa on demand.

Just got off the phone to Rob from eclipsebikes, just posted me out a 48V 1200W motor and controller. Nice guy at *fingers crossed* great service. I'm hoping this motor will last me a good while and maybe even transfer it onto a big boys DH one day.

As for the front forks, They are exactly the same length as my RockShox forks on my 26" mountainbike so that makes life easier, just got to find some triple crown forks with disc mounts that cost less than the rest of the bike put together.

 

[nonlineartom]

I WISH I could find one of these around here! I looked, but I guess they stopped making them a long time ago...

Keep looking, they had a million different names, here in the UK they were called Mongoose, it's the 200W motor but in the 450W american frame, i.e 20" wheels not a 16" and 18" wheels as the american 200W was. I found this on eBay completely by mistake.

 

[deecanio]

They still do come up from time to time, i picked one up for £60 a few months back (uk), not sure what im going to do with it but initially i may just pop an astro into it for fun.

D

 

[nonlineartom]

Heads up to British eBikers, one of these is up for sale on eBay, currently £25


http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320716868822&ssPageName=STRK:MEWAX:IT#ht_1150wt_1141

 

[nonlineartom]

well that's the battery box sorted. One ex British military ammo box, not centered at the moment so it sticks out too far, but looks to be a neat accessible weatherproof solution.

 

[Miles]

What an amazing photo! What are you using to take them, Tom?

 

[nonlineartom]

Just an iPhone

 

[Miles]

I like it

This one is good, too:

 

[nonlineartom]

Thanks.

iPhone 4 - HDR mode photo

Contrast boost and colour temp. raised in camera+ app

Cross processed film effect in camera +

That's it

 

[nonlineartom]

motor and controller arrived, looks like I'm going to have to do a bit of welding / fabricating but it should be very rugged when it's done.

 

[Whiplash]

That is looking really good! It is almost like that kit was designed for that bike!

 

[nonlineartom]

Managed to squeeze in an hours work this evening. Soldering won't get hot enough to melt solder so I've got to wait for a new one to arrive before I can wire up the battery lead and test the motor / controller out. Also got an angle grinder and some 1mm sheet steel on order. It occured to me that this bike is going to try and eat my right leg at every opportunity so a chain guard is in order. I'll give a biscuit to whoever can tell me what type of bottom bracket this is, I've spent an hour with gas pliers and pipe wrenches trying to get rid of it so I can replace it with the new Cyclone bottom bracket and just ended up swearing and bleeding.

also, check out the new suspension coil, bought for pennies off eBay, taken from a quad bike, was 5" now 8" I can now carry a passenger, more than enough room for one

 

[TylerDurden]

I'll give a biscuit to whoever can tell me what type of bottom bracket this is, I've spent an hour with gas pliers and pipe wrenches trying to get rid of it so I can replace it with the new Cyclone bottom bracket and just ended up swearing and bleeding.

I presume it's a threaded race, since it has flats. I have not removed one of mine, so I can't say if it is lefty or righty.