Single disc conversion master cylinder

[Ethos]

Single disc conversion.

Braided steel cables.  Kit from stoltec.  Kept the abs pump.

 

Per advice, I also changed out the master cylinder for a smaller.  11mm from a wr250r.

 

The problem is that the brakes were siezing, it happened twice at speed.  I think the reservoir wasn't big enough.  I went back to the stock master cylinder.  I did try swapping calipers and rebleeding everything just to be sure but that seems to be the issue.

 

Did I do it wrong?  I thought this was a setup others used with success.  Possibly because I kept the abs that the MC was under sized?

Edited May 23 by Ethos

[Windblown]

Having the brakes seize at speed would be hair raising for sure.  I'm running Stoltec kit as well and retained ABS in the front. I installed a Master Cylinder from a Yamaha Yz450F which may be the same unit as the WR250F, not sure on that count.

 

I have not had any issue with the front brake seizing and have around 5000 miles on the bike since the conversion. The only possibilities that comes to mind short of a defective MC is fluid level too high in the reservoir or something not allowing the brake lever to extend far enough to allow fluid to flow back into the reservoir. 

[BADDANDY]

I haven't had that problem either.  I still have full ABS.  I and a few others have this one.

 

https://www.aliexpress.com/item/1005002885434664.html?spm=a2g0o.productlist.main.1.7caf7de3yDUo5j&algo_pvid=77c95a2b-f43c-4d26-90b7-95fbbfc0f33c&algo_exp_id=77c95a2b-f43c-4d26-90b7-95fbbfc0f33c-0&pdp_npi=4%40dis!ILS!141.80!113.43!!!38.39!!%40210307c317035290986607805e8b93!12000022617821087!sea!IL!709946780!&curPageLogUid=ctZNHR46RpnR

Edited May 23 by BADDANDY

[CoreCass]

2 hours ago, BADDANDY said:

I haven't had that problem either.  I still have full ABS.  I and a few others have this one.

 

https://www.aliexpress.com/item/1005002885434664.html?spm=a2g0o.productlist.main.1.7caf7de3yDUo5j&algo_pvid=77c95a2b-f43c-4d26-90b7-95fbbfc0f33c&algo_exp_id=77c95a2b-f43c-4d26-90b7-95fbbfc0f33c-0&pdp_npi=4%40dis!ILS!141.80!113.43!!!38.39!!%40210307c317035290986607805e8b93!12000022617821087!sea!IL!709946780!&curPageLogUid=ctZNHR46RpnR

does the stock lever handle fit in this one ?   if so than its the next mod im gona do

[BADDANDY]

2 minutes ago, CoreCass said:

does the stock lever handle fit in this one ?   if so than its the next mod im gona do

 

I think it may as I did previously get short levers for the stock one and they are now on this one. Hey it's only $30 and you might like the shorty and I may also have the clutch side you can buy off of me.  I'll check if you respond.

[Ethos]

On 5/23/2024 at 1:29 PM, BADDANDY said:

I haven't had that problem either.  I still have full ABS.  I and a few others have this one.

 

https://www.aliexpress.com/item/1005002885434664.html?spm=a2g0o.productlist.main.1.7caf7de3yDUo5j&algo_pvid=77c95a2b-f43c-4d26-90b7-95fbbfc0f33c&algo_exp_id=77c95a2b-f43c-4d26-90b7-95fbbfc0f33c-0&pdp_npi=4%40dis!ILS!141.80!113.43!!!38.39!!%40210307c317035290986607805e8b93!12000022617821087!sea!IL!709946780!&curPageLogUid=ctZNHR46RpnR

 This is the exact one I used.  Possibly mine was defective?

I did check and changed the fluid level, it didn't matter.  Still locked up.

 

Running the stock now and no issues at all.

[BADDANDY]

12 minutes ago, Ethos said:

 This is the exact one I used.  Possibly mine was defective?

I did check and changed the fluid level, it didn't matter.  Still locked up.

 

The 1st one of these from a different seller wouldn't even pump.  I tore it down and put it back together and it worked fine for a year.  Later it was very hard to move the lever so bought this one and it's been fine so far.  Oh, and stock lever will not work on these.

Edited May 24 by BADDANDY

[Fabros]

I use the Yamaha NMAX125 master cylinder with no issues on a single disc conversion.