Ryobi BP42 rings stuck to piston

Rings getting stuck to the piston causing loss of compression is a common problem with this model. It appears that carbon deposits build up in the ring guides causing them to jam in and no longer seal against the cylinder walls.

[@mikevalentine6954]

Update, after massive research and a couple of ring purchases, I believe I found the correct rings for your/my Ryobi bp42....part number 690161006. I just received them today, install them on the Piston which seems to fit perfectly. I will be reinstalling the engine and components this weekend and I will stop back in tell you how it worked.

[@fierrosoft]

did replacing the piston rings fix the issue? Thanks

[@charlesdouthart4805]

Did these rings work for you? Having the same problem.

[@rossshong2539]

Hey mike did those rings work out for you ?

[@rossshong2539]

I went ahead and ordered those rings and they indeed did work out for me I just threw it together quickly but it attempted to fire and I need to reassemble the rest of it

[@Neonixos666]

@@rossshong2539 What is the size of the rings?

[@daltong6898]

Just picked one of these blowers up from the dump, wont start which I'm assuming is why it was in the dump lol I pulled the spark arrestor and sure enough those rings are locked into the piston, which some scoring on both the piston and the sleeve. Luckily I'm a pretty handy guy and will be digging into this first thing in the morning. I'll be sure to use extra care when removing those rings and use some brake clean! I have seen some rings online for this piston supposedly. I'm wondering if larger slots can be machined into the piston on a lathe allowing for a thicker ring to be used?

[@adamaustin4865]

That’s a good idea. It would stop you from needing to tear into it again. I don’t have a lathe so I wasn’t able to try anything like that. One thing I am going to do is sea foam the engine every year to get rid of the carbon deposits that seem to be the culprit

[@daltong6898]

@@adamaustin4865 thanks! I'm gonna give it a try when/if the rings get stuck again, I was able to free them up and it now starts on the 1st or second pull! Great little blower, especially for the price! 😉

[@mikevalentine6954]

I am currently in the same situation as you with the piston rings...have you found anyone that stocks them? I know other Ryobi engines show that you can order the rings for the piston but it all comes down to size and I have not been able to find anyone to take measurements of the rings for me. I do know that the Ryobi 678747003 piston rings are too big in diameter but are correct for thickness. ....so don't buy those!

[@oscararriaza2343]

I have a 1 Ryobi bp42 no Spark already replace the ignition coil and the flywheel any comment to help me

[@fowvee]

The only other component is the kill switch. Remove it from the circuit to ensure it's not shorted.