can't find a sprocket for QS138 V2

[JeroenM]

Hello everyone,

I'm converting a KTM 65 SX to electric, i bought a QS138 70H V2 motor, but i'm having trouble to find a sprocket for this motor.

The KTM uses a 420 chain, and i need a sprocket with 10 teeth.

The motor has the new type spline shaft, specs :

outer diameter 20mm
inner diameter 17mm
6 splines, each 5mm wide

I know that Electro & Co / AMP sprockets have a 10t 420 sprocket for the QS138 , but that is for the old type shaft (spline teeth are 4mm wide, instead of 5mm.

I really hope someone can help me find a sprocket, because otherwise this project will come to an early end


Greetings,

Jeroen

 

[Hummina Shadeeba]

I have the same motor but v3 and got a 420 13t and seems to fit. I’ve never mounted a sprocket like this so not sure but it slides on with little play. When I bolt two bolts n plate to it though it has play along the shaft. I wonder what’s considered a good fit and feel like it needs a spacer between the sprocket and holding plate

https://www.amazon.com/gp/aw/d/B07L553VSL?psc=1&ref=ppx_pop_mob_b_asin_title

 

[Eastwood]

I have the same motor but v3 and got a 420 13t and seems to fit. I’ve never mounted a sprocket like this so not sure but it slides on with little play. When I bolt two bolts n plate to it though it has play along the shaft. I wonder what’s considered a good fit and feel like it needs a spacer between the sprocket and holding plate

https://www.amazon.com/gp/aw/d/B07L553VSL?psc=1&ref=ppx_pop_mob_b_asin_title

I had the same issue with the V3. I put some spacers on the backside of the sprocket that connects to the shaft to get rid of the FreePlay.

 

[Hummina Shadeeba]

I had the same issue with the V3. I put some spacers on the backside of the sprocket that connects to the shaft to get rid of the FreePlay.

I would’ve thought spacers on the front-side of sprocket between the sprocket and the holding plate, so the sprocket is snugged tight against where the splines taper, no?

 

[Eastwood]

Hello everyone,

I'm converting a KTM 65 SX to electric, i bought a QS138 70H V2 motor, but i'm having trouble to find a sprocket for this motor.

The KTM uses a 420 chain, and i need a sprocket with 10 teeth.

The motor has the new type spline shaft, specs :

outer diameter 20mm
inner diameter 17mm
6 splines, each 5mm wide

I know that Electro & Co / AMP sprockets have a 10t 420 sprocket for the QS138 , but that is for the old type shaft (spline teeth are 4mm wide, instead of 5mm.

I really hope someone can help me find a sprocket, because otherwise this project will come to an early end


Greetings,

Jeroen

So is the v2 and V3 same shaft? If so, there’s several companies that make sprockets for the V3.

 

[Eastwood]

I would’ve thought spacers on the front-side of sprocket between the sprocket and the holding plate, so the sprocket is snugged tight against where the splines taper, no?

I tried that way first, but with using a 520 chain the spacers fit better on the back side. Also it was better chain alignment with spacers on the back. That being said, that was just for my particular set up it might be better to put them on the front side for different scenarios.

 

[Hummina Shadeeba]

Fiddling with it I find my assumption that there’s a tapering spline that will lock the sprocket was wrong. Instead it seems to have a bit of play no matter where the sprocket is on the shaft. Is ur sprocket solid on the shaft? I’ve got 1mm lateral play going up n down the shaft (I can fix w a shim) but can also rock it forward n backward. In the bicycle world this would never pass.
I don’t know anything about motorcycles but I think it’s true n the sprocket has a bit of wiggle room in rotation. I’d definitely like to lock it solid.
At least without a tapering spline on the shaft can adjust the chainline.

 

[j bjork]

Why not change the rear sprocket to 428 or 520 instead?

 

[PaPaSteve]

Supersprox does an above average job of providing drawings for their offerings.
They do respond to queries in a couple days.
By taking the time to search their site I was able to find a solution to an unusual application.