Brush Research BC34240AO FLEX-HONE, 3/4"(19mm) Diameter, 240 Grit, Aluminum Oxide, For Aluminum, Brass, Bronze and Softer Non-Ferrous Materials

I decided to rebuild my snowmobile motors as preventative maintenance, and was replacing pistons and rings. The piston suppliers all recommend cylinder prep with these type of ball hones. I bought two hones, one for my 500 cc sleds and one for my 800 cc sled. There are many grits and compounds available, but for Nickasil cylinders these 320 grit Aluminum Oxide versions are recommended. They worked perfectly for de-glazing and refreshing the crosshatch to help in proper cylinder oiling and piston and ring break-in. Choose the ball hone size you need based on the actual cylinder bore diameter. If you buy the hone that matches your diameter it is actually slightly oversized to create just the right amount of pressure to the cylinder wall for effective honing. Using these ball hones takes a bit of technique, but in a home shop environment I found doing the honing in a 5 gallon bucket worked to contain the lube oil from flinging all over the shop, I also made a short spacer to place under the bottom of the cylinder edge inside the bucket to lift the cylinder just enough off the bottom to allow the hone to effectively reach through the cylinder with a full stroke, but not protrude too far through and allow the balls to wrap the lip and bind. Holding the cylinder solid in the bucket also helped to keep the hone centered within the cylinder as cocking it at any angle while holding the cylinder by hand tended to end up with the hone hooking a port or the lip and stopping the process (my first attempts were a bit of a learning curve). Once I figured out how to hold the cylinder and limit the travel properly the remaining cylinders were easy to complete. If you do bind the hone and twist some of the ball fingers, they are very forgiving, and easy to re-set the fingers, straighten them out, and continue on, being more careful about your process. These hones should last forever if you're only using them periodically in a home shop. Using them per the included instructions left a beautiful surface with correctly angled cross-hatch, and made for a perfect top-end rebuild. These are far better than the old spring loaded stone-hones of old, especially for nickasil. These also have a far less likelihood of catching a port if you keep it centered. And if it does catch one due to your (My) own mistakes, it will simply bend around itself but not cause any damage, unlike the potential damage that could be caused if a stone catches a port with the old style hones. Highly recommend this product and the seller.

I uploaded a before/after picture. I’ll let that speak for itself.Also, this works wonders on nikasil without removing the material. Borer size is identical before and after honing. Do it!

It done a really great job honing my chainsaw cylinder. Good product.

My Dad seized his Echo CS-400 chainsaw a while back. I took the junk parts, drove the piston out of the cylinder and examined it. Didnt look great, but not terrible either. Bunch of rust, two opposing minor grooves but no major scoring. Bought a new piston kit. Re-habbed the cylinder with this flex hone. They really work well to clean it up and then cross-hatch the cylinder so the new piston ring will seat properly. RPM recommendations are set by the manufacturer depending on cylinder diameter. Follow those. Also, don't forget to always use this well lubed with motor oil and clean the heck out of the cylinder with warm soapy water (and all the ports and channels in the cylinder too). Once you think it's clean and dry, rub a soft white cloth on the inside of the cylinder walls and its likely you'll see its not clean enough. Do it again. This cylinder head was aluminum, so I chose the AO (aluminum oxide) grit. They have other grits for different metals.Chainsaw's running like a champ now! Good compression. It's like brand new. Only reason it's not 5 stars is they're kind of pricey for, essentially, grit-on-a-stick.

Works great on nikasil chainsaw cylinders.

I needed a flex hone to clean up the inside of a Moen Positemp shower valve, when replacing a leaking cartridge. This worked perfectly to clean the corrosion and scale from the inside of the valve body, and left a pristine surface for the new cartridge to seal against. I’ve used these for years on engine cylinders, so I had no doubt it would do the job needed. These are a bit pricey, but it was less expensive than replacing the entire faucet assembly in my shower.

Item was as advertised, good quality and arrived on time!

These little tools are pricey for a one time use, but "right tool for the job" so worth the cost.Works really great. I used a drill press and hand-held the cylinder I was honing with heavy gloves on.

Zero issues, will be buying other sizes.