Trimmer Repair – Replacing the Piston & Rod Assembly (Ryobi Part # 753-04367)
Trimmer Repair – Replacing the Piston & Rod Assembly (Ryobi Part # 753-04367)

Hi, I’m Mark from
In this video I’m going to show you how to replace the piston in a Ryobi trimmer.
The piston is a central component of your trimmer’s engine. It both provides compression
within the engine, as well as transfers the energy from combustion to the crankshaft,
which creates rotation. The piston assembly is made up of the piston
itself, the piston rings, the connecting rod, and the connecting rod bearing. The most common
reason you need to replace the piston would be worn rings. If you need to replace the
piston, it’s not uncommon to also have to replace the cylinder, as the two work together.
Replacing the piston isn’t the easiest repair, but it’s something you can do yourself if
you follow our instructions. Pistons, as well as many other parts, can be found on our website.
Let’s get started. I’ll begin by removing the rear cover. Now remove the two screws
that secure the carburetor to the engine. Before removing any of the fuel lines from
the carburetor or the lines from the tank, you will want to make sure that you drain
any gas that might still be in the fuel tank. Now I can pull the carburetor away, disconnect
the throttle cable and remove the fuel lines. Now remove the muffler. It’s held in place
with two screws. Now remove the carburetor mounting plate. It’s held in place with
four screws. I’ll also need to thread the throttle cable through the opening in the
mounting plate. As I take this assembly apart, the fuel lines and fuel tank will also come
with it. Now remove the clutch housing and the shaft from the rest of the engine. It’s
secured with four screws. Now remove the clutch drum and the clutch.
Before I do that though, I need to bind up the piston. If I don’t bind the piston,
when I go to remove the screw that secures the clutch drum and the clutch itself, the
crankshaft will simply rotate and I won’t be able to free them. I’ll remove the spark
plug boot and then the spark plug. Now to bind the piston, I’ll insert a piece of starter
rope into the cylinder. The starter rope will coil up and take up all that space inside
the combustion chamber, so that the piston won’t have any travel, and the crankshaft
won’t be able to rotate. Now that the piston is bound, I can remove
the clutch drum and the clutch. Now I can remove the starter assembly. As I pull the
starter away, there’s a wire that leads to the ignition coil. I’ll need to remove
that. Now I’ll remove the flywheel, and the flywheel is secured to the shaft by means
of a taper. There’s a spacer on the crankshaft, I’ll pull that away. To remove it, I’ll
lift up the engine just slightly by the flywheel, and I’ll strike the motor shaft with a rubber
mallet. Beneath the flywheel there’s woodruff key
that indexes the flywheel to the crankshaft, and I’ll remove that key. Now I’ll separate
the cylinder from the crankcase. It’s secured with two screws. I’ll now carefully pull
the piston from the cylinder, and separate it from the crankcase. Now I’ll remove the
cylinder gasket. I’ll use a blade to remove any residue that’s left by the gasket. Now
I’ll install the cylinder gasket. Now we can install the piston.
The first thing I’ll do is apply some 2-cycle oil to the piston itself. This will make it
go into the cylinder a little easier and won’t scratch up the cylinder. Next I’ll compress
the piston rings, and I want to make sure that I have the ring end gaps lined up with
the roll pin in the ring groove, like that. Now install the piston into the cylinder.
The piston needs to be oriented correctly. You’ll notice that one side of the piston
skirt has been cut out. The other side is just straight. This cut out side needs to
go on the side of the cylinder where the ignition coil is. That’ll be the same side that the
counterweight is on the crankshaft. If you get the piston in backwards, the skirt will
strike against the counterweight. So, I’ll hold the rings in compression and
slide the piston into the cylinder. Now I’ll install the connecting rod onto the crankshaft.
I’ll slide the cylinder into the crankcase and secure the cylinder with the screws. Now
I can install the flywheel. First, I’ll place the woodruff key into the slot on the
crankshaft, give that a little tap to seat it in place, and now I can install the flywheel.
I want to make sure that I line up the slot on the flywheel with the woodruff key. The
flywheel may stay a little loose at first, it will get tightened up later when we install
the clutch. Now we can reinstall the starter. First I’ll slide the spacer back onto the
crankshaft. I’ll connect the ignition wire back to the ignition coil, and then I’ll
slide the starter over the crankshaft. As I do, I’ll tuck the wires, the ignition
wires back into the starter housing. With the starter back in place, now secure it with
the screws. I’ll reinstall the base and secure it with its screw. Now install the
clutch. First comes the large washer and then the clutch. If you’ve removed the piece
of starter rope that was in the cylinder to keep the crank shaft from rotating, go ahead
and reinstall that now. And then I’ll tighten down the clutch with a pair of adjustable
pliers. Now install the clutch drum. First comes the
small spacer washer, and then the drum. And I’ll tighten down the internal screw inside
the drum. Now reinstall the spark plug and replace the spark plug boot. Now install
the crankcase cover. As I reinstall the fuel tank, I’ll want to make sure that the rubber
bumper is in place that isolates the tank. There’s also a bumper that goes on the crankcase
cover. Make sure the gasket is in place and slide
the cover onto the crankcase, and now secure it with the screws. Now install the muffler
gasket and reinstall the muffler to the engine. Now reinstall the upper shaft to the engine.
As I do that, I need to thread the throttle cable through the engine housings. I’ll
secure the clutch drum housing to the engine. Now install the carburetor gasket.
Now reinstall the throttle cable back onto the carburetor’s throttle linkage. Now install
the incoming fuel line to the bottom of the carburetor, and the line leading to the primer
bulb on the top. And I’ll secure the carburetor, as well as the choke plate, with the screws.
As I tighten the upper screw, I want to make sure I have the choke plate lined up, as well
as the wavy washer, so it doesn’t get pinched by the screw. Now reinstall the back cover
and secure it with the screws. And now you know how to replace the piston
assembly on your Ryobi trimmer. If you found this video helpful, be sure to give us a thumbs
up and leave a comment.

54 thoughts on “Trimmer Repair – Replacing the Piston & Rod Assembly (Ryobi Part # 753-04367)”

  1. Dan Webster says:


  2. Typey1 says:

    Great video

  3. michael smith says:

    fantastic tutorial PLEASE DO MORE

  4. JM Padilla Rojas says:

    how about the engine oil..

  5. George Harris says:

    You have awesome videos! I have a question you may be able to help me with. I have a Ryobi SS30 that I can not get started. I have watched several of your videos cleaned the carb because I thought that was my problem because when I shot some started fluid in the carb I thought it was trying to start but it never did. I have checked the exhaust and the spark arrestor screen and they are fine. I have also checked for spark and I have good spark at the plug. The only thing I can think of is maybe the piston and cylinder head may need replacing? What are your thoughts on this issue. Also, do you know the factory settings for the high and low carb adjustments because a guy at work said that they needed adjusting when I first began having a problem with the machine so he adjusted them and now it will not even start….even with starter fluid in the carb. Any help would be greatly appreciated. Thank You

  6. javier rosas says:

    why don't star the engine?

  7. Jose Feliciano says:

    Gracias por explicar tan claro.Puerto Rico)

  8. 1234tric says:

    I would have liked to see a more modern up to date gas weedwacker piston replacement. It presents a different set of problems. Like my screwdrivers were ย ย to big to get in the shaft hole to remove the clutch assembly screw. So I used a different method to get to the screws to remove the head. Great videos as always.

  9. robert neash says:

    My piston ring has snapped but don't know what size the rings are

  10. Dora Poynor says:

    Great video! Thanks you may it look easy!

  11. chozen0018 says:

    holy hell

  12. William I says:

    Good video

  13. Huhyvfbjvv Hhvgvbhv says:


  14. Bobby Benn says:

    thanks for the video, does ryobi and troybilt parts interchange? thanks

  15. Frank G says:

    Wouldn't that new ring just burn up cause the cylinder wasn't honed?

  16. AquaCarb says:

    So helpful I'm just going to buy a new trimmer. My Ryobi has been worked on twice. Each time at a cost of $96 I kept hoping that that next time was thee time. And I had $150 in attachments – Edger and blower – that I didn't want to give up. Now it pulls easy and I'm pretty sure the rings are shot. There are some nice electrics where I dont need to buy gas Im gonna look at.

  17. lawnmowerrecycler says:

    Nice video, thanks.

  18. carlos casas says:

    is possible that even the assamble is done correctly the engine has the wrong timing? I rebuild one, has everything new (carburator, gaskets, fuel lines , fuel , spark plug ) , comprensiรณn is fine ,the coil has good spark and doesn't start .I will apreciate your help. [email protected],

  19. hemanta chutia says:

    Really fantastic………

  20. carlos casas says:

    is working now well

  21. Kimutai Rop says:

    Please show us how to replace the timing belt of ryobi x431. My belt has stretched and slides off the camshaft gear. Also show the correct way to set the timing.
    Thanks for your great videos.

  22. Penta Comstat says:

    Thank you for a clear demo. Enjoyable and informative.

  23. vikas kumar says:

    How fix peddy cutter in it

  24. John Wyman says:

    I find it interesting that the new piston had two rings and the original piston only had one. I wonder why?

  25. Norman Kniepkamp says:

    made it look easy hopefully I can do the same on mine haha

  26. John Wyman says:

    Are the replacement parts OEM Ryobi? If not what brand are they? I also noticed that rod looks stronger also.

  27. sanddollar says:

    hi,, what is the bore size of piston on a echo rsm 225???????

  28. barun sangha says:

    When you install the crankcase cove do you need to put some sort of oil

  29. Winston Clarke says:

    Wonderful video Mark keep it up.

  30. jim s says:

    Excellent video

  31. Old Dirty Burt says:

    absolutely fabulous video. Did you need to take off the entire front of the trimmer to get to the piston and swap it?

  32. Al Duarte says:

    Thank you everyone for I am more informed now then I was. Great program YouTube. Also out till next time.

  33. Chad Lasher says:

    What is the purpose of taking the muffler off? I have a Cub cadet cc2020, a very similar model, and able to take the Piston area apart with removing the muffler. But i will say that either that or something has caused the motor to refuse to start and feel stiff

  34. ritchietheforky says:

    Needing to replace piston and cylinder on a Ryobi PCB30cc have you got a video for this fantastic blogs very helpful

  35. Chris Ogley says:

    great video!

  36. seadooman o says:

    Pointless to change piston without new bore or honing it will be short lived

  37. Kedar Bhide says:


  38. Michael Serrano says:

    5:19 like watching deep penetration anal porn. XD

  39. Jace Henderson says:

    You can get the piston out without having to do anything with the clutch or flywheel. Unless my TroyBilt TB70SS is different from that ryobi.

  40. lamanchadale says:

    Replacing the ring alone will do nothing to restore compression . Even honing the cylinder does not work to match the piston ring to the cylinder. I have lots of Ryobi 31cc engines I use on my giant scale RC airplanes. I have tried all sorts of things to restore low compression with new rings, and nothing works. It appears the cylinder needs to be bored out and honed to restore compression. It is cheaper to buy a new engine than do this, as oversized pistons and rings are not available. Just buy a new string trimmer.

  41. not registered says:

    Can you make a video on how to change the Piston and replace the rubber timing belt on 4 cycle Ryobi 430 model weed trimmers? Please, I use the engine for a homemade scooter and need to know ASAP.

  42. WV591 says:

    Why you don't sell those rings separate?

  43. Geo Loussian says:

    its bad to start with the rod bearing dry , lubricating it is highly recommended

  44. Grant Ottman says:

    I need help! When I attach the edger to my echo trimmer, the enter shaft starts to turn. I constantly have to stop and straighten it back. How do I fix this problem?

  45. Hoony Fan says:

    That was a nice tutorial. I was surprised you didnโ€™t mic the cylinder wall and do a lite hone before installing the new piston. Is there a reason for not taking that measure?

  46. wacio says:

    What is the reason you're removing the clutch and flywheel – it almost looks like unnecessary. Would it be possible to just remove carb, exhaust and than cylinder. Didnt see anything preventing to do repair without disassembly of the front side of the engine.

  47. Eric Whitfield says:

    Excellent video. Please make more, Thank you

  48. WW III says:

    No honing.

  49. cbnx82703 says:

    No reason to even remove the flywheel on this unit…! Why did you do it?

  50. mrbigg7255 says:

    Great video. Thanks.

  51. Ion Chele says:

    Nice tutorial !!!

  52. George Moreno says:

    great videos and great instructions, do you have a web site for more?

  53. yrulooknatme says:

    why is my crank rod pin loose on the crank on my troybilt blower???

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