Another Ninja 250 Project

[Jonny Panic]

Hey guys,

I had a CB750 project that I started long ago, and ended up selling to fund my move to the west coast. I used to post on here as jpanichella. Since then I've had an XS650 and a CB360, and after spending about 3 times more time wrenching than riding, I'm finally thinking hard about building an electric commuter bike. The plan right now is:

- 2000 Ninja 250 frame, I'm going to go pick it up next weekend. It's titled, the engine threw a rod and it's on non op. Great base though, light frame, good brakes.
- 10 Nissan Leaf Cells
- ME1003
- SPM72400
- 5 of those MiniBMS semi-distributed boards set for 4.2 HVC
- BMS Battery 900W Bulk Charger
- The cheesy little electric motorsport DC/DC converter
- Albright contactor
- Magura throttle

Drew the frame up super rough in CAD based on photos, just to get a sense of component placement.



Still trying to sell the CB360 in order to fully fund this project. I'm sure I'll have lots of questions for you soon, but for now I mostly wanted to say hello.

[Electro Flyers]

This bike is heavily dependent on the engine as a stressed member to keep the front of the bike tied to the rear- something you need to address when the engine is removed. Here's what can happen when the engine is removed as stressed member on this bike:http://forums.ninja250.org/posting.p...&t=87006&tro=1

Apparently, in this case, the top engine mount bolts were left out (or fell out). This might have been done when the mounts were removed for valve adjustment or top end access.

Also, in this quoted forum, there's a suggestion for reinforcing the frame.

[Jonny Panic]

Thanks for the link, good reading.

I'm familiar with that weak point in the frame, right now the plan is to make the motor and batteries one, solid piece suitable enough to be a stressed member for the frame. I'll also consider adding a gusset to the weak point mentioned, but I'll have a long discussion with my engineer/welder friend.

[DRZ400]

That's what I did. Built my motor and battery mounts in place. Then gusset welded them together to make one strong piece.

[ericmick]

Good luck on the build. I'm doing the exact same thing, Ninja 250, ME1003, Leaf modules, SPM72400. I do plan on one extra leaf module, 11. I have not worked out the frame support yet, but almost there. It's a negative support member (pull) and light metal support with pack and motor mounts should work. I do like the simple addition done by billmi in the thread referred to by Eltro Fly (Ninja250 Riders Club :: Topic review - bike sagging so much, wont it lean on sidestand). The advantage is that all future battery/motor reconfigurations are supported without concern for frame support. The disadvantage is reduced open space. Crap, as I type I'm convincing myself to just use the battery/motor support, same as DRZ400. Sorry, I digress, just wanted to say good luck and keep us posted.

[Jonny Panic]

Hey DRZ400 and ericmick

I've been following both of your builds, I appreciate the words of encouragement. Although making the battery and motor mounts one cohesive unit makes a modular system more difficult in the future, I'm hoping that it will make service and installation easier. I want to have the entire high voltage system exist as one big "chunk" that I can jack up and bolt into the frame. When I have time to sit down with my welder friend, I'll update this page with more CAD drawings to help illustrate my intentions a bit better.

[Electro Flyers]

Good luck on the build. I'm doing the exact same thing, Ninja 250, ME1003, Leaf modules, SPM72400. I do plan on one extra leaf module, 11. I have not worked out the frame support yet, but almost there. It's a negative support member (pull) and light metal support with pack and motor mounts should work. I do like the simple addition done by billmi in the thread referred to by Eltro Fly (Ninja250 Riders Club :: Topic review - bike sagging so much, wont it lean on sidestand). The advantage is that all future battery/motor reconfigurations are supported without concern for frame support. The disadvantage is reduced open space. Crap, as I type I'm convincing myself to just use the battery/motor support, same as DRZ400. Sorry, I digress, just wanted to say good luck and keep us posted.

You need to explain what a "negative support member" is

[Stevo]

You need to explain what a "negative support member" is

I think he means it's a tension type of stress/force, not a compression force. This thread has helped me in my build too. Thanks.
I'm deciding how to build a stressed battery compartment myself. That way the battery compartment can be swapped out easily just by fabricating new ones as future battery designs dictate, and the motor and other bits wont have to be moved. The mounting points will be a permanent part of the frame.

[Electro Flyers]

Good. I Googled the phrase and could not find it. I thought maybe some new levitation or anti-gravity device had been invented. In a static display or in a perfectly smooth, strait world, it's true, there would be little need for replacement compression members if the engine were removed. Cables or chain could be used. But, in the real world of acceleration, braking, bumps, pot holes, RR tracks, leaning in curves, the occasional bumper or curb, etc. replacement compression members would be needed.

The compressive forces may be less than the tension forces, and there might be less of a metal fatigue (permanent bending and cracking) problem, but the overall frame deflection would be much greater. I've seen this in bikes I've built as front end hop. Also, as that queasy (that's a bonafide design term) feeling you get between your butt on the seat and your hands on the handlebars as the bike excessively shifts around between your legs. This is most disturbing leaned over going around bumpy curves. Some of that has to do with the torsional stiffness of the frame - another design consideration.

Let's see what JP's engineer/welder comes up with.

[Stevo]

I'll be waiting to see what they say also. My frame is different than the Ninja... it's a "perimeter" style frame, more like a KX 250... very strong/rigid back bone.
I think the down tubes are not seeing too much stress in either direction.