Brake hone tool (Flex-Hone)

I have two master cylinders I need to rebuild. Both for my XJ550 SECA's. The bores have some pitting as you can see from the videos below. I had rebuilt the M/C on my KZ900 but it had a very small leak so I finally replaced with new generic M/C which I purchased on eBay. But I really would like to keep the originals on the SECA's and KZ. So I purchased this Flex-hone for $11.71 shipped to my door. Will post the results once I use it. It will be worth every penny if can save these two M/C's. If it works, I will order a 14mm version for the KZ M/C. Will try rebuilding it one more time after honing and see if that fixes the leak.


4theKZ1000 suggested this tool and I found it for a good price at zoro.com. Ordered it Monday night, came this Wednesday morning.

Here is a short clip before attempting to clean the bore:

Before Cleaning - Click Here

I tried the wooden dowel method using 400 grit wet and dry sand paper to recondition the bore. Here are the results (still some pitting left):
After Using Wooden Dowel Method - Click Here

I'll be watching for an update.

Me Toooo !!!!

I tried honing an old master with one of those hones and it destroyed it. Finish was way too rough and it's impossible to keep the bore round and consistent. No loss since it was pitted already. Got lucky and found a decent one on ebay. The OEM bore finish is smooth and polished, unlike what you will get with a hone. There are lots of cheap new Chinese masters on ebay so I'd try to find something to adapt before going down this honing path.

Will have to see Nessism. What grit did you have? I purchased the 240 grit. I could have purchased a 320 grit for around $17.00. But since the 400 grit sand paper wasn't doing it I figured I would try the 240 grit. I figure I have nothing to loose other then $11.00. If the surface is rough after the hone, I will use my wooden dowel on a drill method again with 600 grit to get the smooth final finish. Keeping my fingers crossed.

Tried out the hone this evening. Below is link to a short clip show the results. Still some slight evidence of pitting. This is after hitting it about 3 or 4 times with the hone and one more time with the wooden dowel using 600 grit paper. Not too bad I think. I just might let it fly and proceed with rebuilding it to see how it feels on the bike. Hopefully there is not enough pitting there to cause the seals to be damaged. I can truly say I have done a much better job on this M/C than I did on my KZ's M/C (which leaked slightly). Any opinions out there on the results. I would like to hear from people that have rebuilt truly nasty M/C's. How did your results compare to this example? Have you had any issues after the rebuild?

Flex Honing Process - Click Here

After Flex - honing - Click Here

The conclusion I have so far is that the hone does work nicely. The 240 grit works well but slow. I kind of wish I had the 180 grit for the first pass in order to get the bulk of the imperfections out. Then follow that by the 240 grit version and then a 360 grit pass. But 240 alone works well, just will take about 3 to 5 passes depending on how much pitting you may find and how deep they are.

If your bore was 14mm originally, what's the ID going to be after you get done?

If it's important to keep the original master cylinder, it can be bored and re-sleeved back to stock. Not cheap though.

This was for a 12.7 (1/2") bore. Not sure what the ID is now after the honing. I have the proper measuring tools so I will take some readings to see what I have and make sure its not out of round. I am hoping its a minimal change and the seals can compensate for the change. Remains to be seen. If it turns out the ID has enlarged too much, then I will purchase a cheap new M/C for now. But will get this re-sleeved. I am trying to get one of these bikes back to original. I am leery about purchasing an original used M/C from eBay. No guarantee I won't end up with one with the same problem.

Just a thought....is there enough room to bore the 12.7 out to 14mm. That way you keep the original and you can use the larger MC internal parts. Seems to me that might work but don't know for sure

steell wrote: If your bore was 14mm originally, what's the ID going to be after you get done?

If it's important to keep the original master cylinder, it can be bored and re-sleeved back to stock. Not cheap though.

Has anyone done a thread on this because I have 5/8 master that I would like to re-sleeve.

bluej58 wrote:

steell wrote: If your bore was 14mm originally, what's the ID going to be after you get done?

If it's important to keep the original master cylinder, it can be bored and re-sleeved back to stock. Not cheap though.

Has anyone done a thread on this because I have 5/8 master that I would like to re-sleeve.

I remembered this posting by Tom:
Master Cylinder re-sleve - Click Here

Maybe he can give some more details.

bluezbike, I'm sure that is possible. Just would be hard to find the perfect 14mm piston kit that has the exact dimensions as the 12.7 mm kit. Would have the same lengths for the springs and piston and distance between the seals. Also the proximity of the seals relative to the end of the piston. So the would work properly with the holes from the reservoir. The diameter, is the only thing that would be different. I'm just assuming all this of course.