Yamaha YZ250F

[speedy1984]

I usually charge to 120,5-6V, it then usually drop to 120,3-4V before I get to the track.
I use regen, but I can only choose between slide regen or regen with a button.
I use slide now, but even if I use the button I dont get more than short peaks of 40A maybe?

I have so far never been to a track that starts with a lot of braking, so it so far never been a problem.

Yeah its annoying they dont have variable regen but are well.I actually dont use either slide or button myself,i find my build slows down off throttle well enough i can deal with it.Also if the cells settle there then i would go 29x4.14v.I mean it makes very little difference but pulling what you can out of a build im all about it.Ive just gone from 26s to 28s myself so glad to hear your controller is handling the 30s well.

 

[project@sr]

Are you using Qs180 90ah with 72v / 96v??
What would be the best configuration for fastest acceleration for a dirt bike??

 

[j bjork]

No, I am not using 72/96V as you can see in the last few replys.
I have 108V nominal (30s), but that dosent really make sense as my controller cant handle more than 120.5V.

To get max acceleraton need a powerful controller and battery.
Then get the best tire you can find and play with gearing and phase amps to find a balance between traction and wheelies over as big speed range as possible I suppose.

 

[j bjork]

Time for some repair work:

I used a 3mm thick piece, I hope it will last a while.
Some protection over that area would not hurt.

Washing time last weekend :wink:
The snow is gone now, but it was a reminder that winter is coming.

I started looking for studded tires, and found this pile as a package deal.
Now I have tires for next season for sure

 

[harrisonpatm]

How's your battery managing in the cold?

 

[j bjork]

How's your battery managing in the cold?

That is something I'm trying to evaluate at the moment.
I think it lasts shorter than before.
But that is something I thought was starting to happen even before it was getting cold, so it might not be related.

Last weekend I was at a sandy, fast track with few and rather easy obstacles.
The challenge there is mostly to get a good flow and not loose to much speed in the curves.

One lap is about 12km, I did them in 18.45-19.00min. I got 2 laps out of a battery with very little left.
I expected to have about half a lap left on the batteries.

It was probably the first battery that started at about 15 degrees and was 28-29 degrees when it was done.

Today I was at a rocky, muddy and slower track.
One lap is about 9km, I did them between 23-26 min..
There was a fair share of crashes, got stuck at least once etc.

I did 3 laps on a battery, I expected to have at least half a lap left.

The first battery started at about 15 degrees, finished at about 20 degrees and was rather slow to get there.
The second battery started at about 10-12 degrees somewhere, but I forgot to check were it ended.

Both times it was about 0 degrees outside.

I stated with the trailer in the garage, both batteries was about 18-19 degrees when I left.

I closed the doors at the track to keep as much heat in the battery as possible.
Maybe I will have to consider some sort of battery heating when it gets colder.

A bonus picture after todays ride:

 

[Jocke_D]

I really love you're using the bike as intended. Great work!

 

[j bjork]

I really love you're using the bike as intended. Great work!

Thank you
They call it dirt bike, so I guess it should get dirty
I m not very interested in looking at shiny things, when I build something I want to test it hard.

What is it they say, "if it doesn't work, chrome it" :wink:

At the first lap I had nasty chain noise, it sounded a lot like something rubbing.
I know the rear chain is a bit "stiff" (doesn't bend as it should), but I got worried that is was something with the primary chain.
The noise went away, but I opened up the primary later to have a look:

Looks pretty good, no rubbing anywhere.
But I have got some slack on the chain again :?
The cork seal on the lid seems to work fine. Maybe I should make one for the motor too, so I can adjust the tension again without taking everything apart.

I noticed it was getting hard to find the rear brake:

Was able to straighten it out pretty good.

On a rocky climb on my last lap the bike stopped with a noise.
I noticed it was the chain that had jumped off.

I had to straiten out the chain guide, but it seems ok now.
Did I mention there were rocks :wink:

 

[JRP3]

Do you have any venting in the primary chain case? Wondering about pressure buildup from heating.

 

[j bjork]

Yes, I have a 6mm id tube with a fuel filter as oil separator.
There are pictures of it earlier in the thread.

 

[j bjork]

It was really time to get the studded tires on the bike.
And then also time for 18" rear wheel:

I didnt do it myself, I left it to a professional.
I think the spokes is not very tight though :?

Anyway, finished and I put on the tire.

It will be interesting to see how this is to ride

 

[Eastwood]

I didnt do it myself, I left it to a professional.
I think the spokes is not very tight though :?

So the spokes are not tight, but does the wheel spin true without the tire? If so, you could use a wrench and turn each spoke nipple equally a quarter or half turn to tighten the wheel up. You wouldn’t have to worry about truing if it’s already straight, if you evenly tighten each spoke nipple.

Or you can get a spoke “torque” wrench and bring each nipple to spec, which would be the best method but definitely not necessary.
45 to 50 inch pounds for the nipples.

and love those blue excel wheels
That’s the best part about Yamaha, you can match the blue excel rims lol

 

[xormic]

Have you gotten any 0-60 timing on the setup?

I'm also planning on using a qs180 90h motor on a shifter kart. Still thinking what controller I want
I was thinking about getting a ND721200. What are your thoughts?

 

[j bjork]

So the spokes are not tight, but does the wheel spin true without the tire? If so, you could use a wrench and turn each spoke nipple equally a quarter or half turn to tighten the wheel up. You wouldn’t have to worry about truing if it’s already straight, if you evenly tighten each spoke nipple.

I did turn each nipple about 90 degrees, but I didnt check how true it was before I put the tire on
It looks ok, and I get a new chance when it is time to take off the studded tires.

xormic, I havent tried any timing on this bike. I have an app I tried to use on the ktm, but was not able to get any good reading.

I think there are some speed numbers in dougf:s thread when he tested his bike in drag racing. I would expect mine to be a little faster 0-100 km/h because of lower gearing and higher voltage. That is if it would be possible to get good traction and keep the front wheel down..

I would go for higher voltage. I think you will be able to get a little more power with only a little more heat.
Not sure about phase amps, it might be a good idea to go for 1800 even if you dont need it. The controller would probably run colder if you run 1000pA on a 961800 than a 961200.

 

[xormic]

Could you please send me a video of it running. Flybys, offroad riding, anything please. In making my final decisions before I buy this motor.

 

[dougf]

xormic, there are some performance figures in my thread. Most people who ride my bike say its more powerful then a 250F but not as agressive as a 450. I do however run pretty high gearing with a top speed of about 140kph depending on SOC. I havent been back to the drags since melting my battery but I ran a 13.6s at 140kph. 1.9Sec 60ft. cant remember my 8th. Because of issues I had the motor stuttered between 90-110kph costing time but if I fixed that it would be a low 13s bike. Be aware that if you want to gear it lower like Bjork you will need to use a countershaft or run a comically big rear sprocket.

If your building a MX bike I wouldnt overlook the 138, Its a lot lighter, has inbuilt reduction, draws less power meaning you can run a lighter battery and if geared for a sensible top speed will still pull nicely. Dont get me wrong I like the 180 but if I built an MX bike Id go the 138.

Doug

 

[xormic]

Just keep in mind im planning on using this motor on a 160kg shifter kart. Can you check if I'm on the right steps of planning. Im planning to use the 180 with a nd721200.
For my gearing I'm simply planning on using a 14t sprocket on motor shaft, and 28t sprocket on Axle.
Do you think im already making a wrong steps that can that can later cause a problems.
Also how did you have your motor shuddered?
Could you remind me again. How much BA and PA are you running, and on what far driver controller?

 

[dougf]

Shifter cart, ok, not the 138 then, maybe something more powerful. Be mindful of your continious power draw. My motor on the hwy sitting at 13kW will slowly heat up. I run out of battery before it overheats but just something to think about. Im using a fardriver 961800, same as bjork, but my battery is only 24s.
Not sure what you mean by shuddered.
I have my controller set for 500BA and 1600PA. My bike doesnt seem to respond to higher battery amps. One day it will make it back onto the dyno and we will see.
qs180 and 961800 is a good combo, probably around 40 to 50kW peak.

Doug

 

[SlowCo]

Just keep in mind im planning on using this motor on a 160kg shifter kart.

Check out Nuxlands electric kart build thread:https://endless-sphere.com/forums/viewtopic.php?f=34&t=68543
Lots of great info to learn from. Especially real world testing, power and temp read out etc. I think you need to go for the FarDriver ND961800 and air cool the motor internally like Nuxland did. And you'll need to build a serious battery pack to feed this combo, especially if you want it to last multiple laps... :wink:

 

[j bjork]

Be mindful of your continious power draw. My motor on the hwy sitting at 13kW will slowly heat up. I run out of battery before it overheats but just something to think about.

Thats interesting, I suppose hwy= highway? So the wind at higher speed is not enough to cool it down?
How warm do you get it?
I have always wondered when the discussion about what a qs138 70h can take comes up. I have never had a problem with the old bike in the woods, but then it is just short bursts. If the 180 90h heats up slowly, I guess a 130 70/90h would heat up rather fast on the street.

I have my controller set for 500BA and 1600PA. My bike doesnt seem to respond to higher battery amps.

Why do you think that is, battery sag or motor or what?
I mean, that thai dragbike seems to eat a lot of amps..

One day it will make it back onto the dyno and we will see.

Doug

xormic, I dont have any more videos than the ones I have posted. And I dont think my videos would be much use to you anyway, to see what the motor can do it would take a fast rider and a fast track.
You can always have a look at the drag bike a few pages back.

Maybe my chase of smaller sprockets for the primary reduction has ended:

I found that qs has them
A bit expensive, and the shipping was annoying.
I think it was like $15 in shipping for one. I thought it would be about the same for for a few, but no.
I planned to buy 5 or so at first,three 11t and two 10t. But the shipping went to $50 or something, so I ended up with just two 11t.

The finish is a little crude, but so far the fitment seem decent.
But I have only tested on the edge of the shaft beside the front sprocket on the secondary reduction.

 

[xormic]

I have my controller set for 500BA and 1600PA.
Doug
[/quote]



Why do you have it set at 1600pa, does 500ba make 1600pa? Or did you just set it at the highest number.
Cause wouldn't 500ba make only like 1000pa? And jot 1600pa

 

[dougf]

I believe it gets pretty well sheltered by my battery and bash plate. Unfortunately the temp sensor doesnt get recognised by the fardriver controller, something I need to look into, but after about 25kms its getting borderline too hot to touch so around 70Deg. Otherwise when sticking below 8kW continiuos is barely gets above ambient. Keep in mind here in Aus its summer right now and Im riding in 30Deg weather.

In my case Id say the battery sag starts robbing some power, especially when its starting to drop in SOC. I only built it with 300A in mind. Getting up to 7C current draw which is a bit high to not sag.

Xormic, no particular reason why the PhA is set to 1600 instead of being maxed out.

Doug

 

[xormic]

Do you think that if I give the qs 180 motor 600 battery amps continuously at 72v, that it would be to much for it?

 

[j bjork]

43kw continous is likely too much for a 8kw continous rated motor, yes..
It would also take a 43kwh battery for one hour at 43kw, and it would be a car not a cart.

 

[xormic]

43kw continous is likely too much for a 8kw continous rated motor, yes..
It would also take a 43kwh battery for one hour at 43kw, and it would be a car not a cart.

Does that mean that the ND721200 is to much for the motor? Because it's rated 600 battery amps and 1200 phase amps..