Trimmer Repair – Replacing Carburetor Diaphragm & Gaskets (Ryobi Rebuild Kit # 791-180091) Click here for more information on this part, installation instructions and more.

This particular gasket-diaphragm repair kit is specific to Ryobi manufactured brands, including Ryobi, Troy-Bilt, Bolens, Yard Man, and MTD. To find a gasket-diaphragm repair kit specific to your model, visit

If your Ryobi trimmer is showing any of these symptoms; installing a gasket-diaphragm repair kit could solve your problem:

1) Difficulty starting
2) Rough idle / rough running
3) Colored smoke from exhaust
4) Excessive fuel consumption
5) Starved for fuel
6) Fuel leaking from carburetor
7) No-start condition
8) False-starts
9) Loss of power part number: 791-180091

Tools used for this repair/replacement:

1) Receptacle for draining fuel
2) Phillip’s screwdriver
3) Long-nosed pliers
4) Pick or small screwdriver
5) Carburetor cleaner spray or ultrasonic cleaner
6) Basin for collecting overspray (if using carb cleaner)
7) Air compressor and blower nozzle

Get model-specific repair help from Learn how to troubleshoot, diagnose and repair your power tools and equipment with illustrated instructions, hundreds of step-by-step repair videos, and our DIY forum. If you have a power tool or appliance problem, we can help.



19 thoughts on “Trimmer Repair – Replacing Carburetor Diaphragm & Gaskets (Ryobi Rebuild Kit # 791-180091)

  1. >>>    I love this Husky has all the power you will ever need unless you are a lumberjack. Perfect for orchards of any kind. Starts easy, chain adjustment is on the side, and the power on/off switch and the choke are right next to each other.

  2. Hopefully someone knows the answer to this, but i got a Zama carb diaphragm kit. And on the reed side they gave me 3 pieces, the gasket, a thin plastic film reed as in this video, and another thin rubber reed. When I took my carb apart it only had the plastic reed. Is the other rubber reed an extra I don't need which is for another model carb?

  3. DISCLAIMER: Turns out that the demo in this video applies only to the Wibro carb. The Ryobi 725R came with two carbs, one by Zama and one by Wibro. The kit that is the default from this supplier and most other suppliers is for the Zama carb. You can get the rebuild kit for the Wibro, like this demo shows, from eparts, but you have to do a search within model for carb and look for the Wibro. It turns out to be about $43 for one set of gaskets. The entire carb sells for $46 from the same supplier so it really makes no sense to rebuild the Wibro's as this demo is doing. You might as well buy a whole new carb for three extra bucks. If you buy the Zama carb, and it fits your machine, it costs about $62 and the repair kit for 2 sets of gaskets costs about $34. In the end, I don't know why they even post this video, because economically it makes no sense to rebuild these Wibros like he's doing, unless you like to tinker, I guess.

  4. Thank you for the detailed instructions, followed them accordingly for my ryobi chainsaw's (C4618) carburetor . Question regarding the fuel lines. What do you mean to "line to the primer"? There is a hose coming out that I never detached from the careburetor, but didn't seem to be connected to anything. Any idea?

  5. I rebuild my walbro carb with a kit. When I pump the bulb it makes a hissing sound and does not fill with fuel. But the fuel comes out of the front of the carb and soaks the sponge air filter. Do you think I have connected something wrong?

  6. Nice work BUT that link to the gasket/diaphragm kit doesn't look like the parts you are replacing. In fact, you show off the parts at the beginning of the video but then don't use those parts. Your tutorial is great except for this part issue. In the end, I didn't find a kit but instead looked up the carburetor and purchased the parts individually, which wasn't that expensive. ($6.20 not including tax and shipping)

  7. Hi, Great video :),can i ask a question plz?…..ok i will lol…..i have bought a chainsaw and been told it has had a full service , gasket & diaphragms replaced etc….it starts fine..the idle was too low so iv sorted that but to get full revs i have to feather the throttle untill the revs build up then its fine if i just pull the throttle it chokes and dies …what could that be if all of the above was really done? oh and new spark plug.
    thanks in advance

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