4 Cycle FULL CRANK Straight Shaft String Trimmer

Model: #RY4CSS

4.5 | 1686 Reviews
The 4 Cycle Straight Shaft String Trimmer brings power, less hassle, and performance to your lawn maintenance. The 4 cycle low emission engine and REEL-Easy bump feed string head make trimming your yard a breeze while keeping the air around you cleaner. The straight shaft allows for extended reach trimming under decks, around obstacles, and in hard to reach places. With the RYOBI 4 Cycle string trimmer, you no longer have to worry about mixing gas and oil. This innovative unit is attachment capable, accepting all nine of the Expand-It universal outdoor attachments. Backed by a RYOBI 3 year warranty while offering less hassle and mower power, the RYOBI 4 Cycle Straight Shaft Trimmer is the residential string trimmer of choice.


Ryobi three year warranty logo

All RYOBI Outdoor Products purchased on or after 1.1.09 are covered by a 3-year warranty. All RYOBI Portable Power Tools and Bench/Stationary tools purchased on or after 1.1.11 are covered by a 3-year warranty.

View our current catalog for new product releases and the latest RYOBI savings!

Ryobi Help+

Your one stop destination for tips & techniques, manuals, troubleshooting, FAQs and more!


  • Engine Type: 4 Cycle/Stroke Low Emission Engine
  • Trigger: Variable Speed Throttle
  • Cutting Path: 18 in cutting swath
  • String Diameter: .095 in. dual line
  • Line Advancement: Bump Feed
  • Attachment Coupler: universal attachment coupler
  • Weight: 11.8 lb.


  • S430 Straight Shaft String Trimmer
  • Ergonomic Front Handle
  • Straight Shaft Grass Guard/Deflector
  • ReelEasy™ String Head
  • 4 Stroke Engine Lubricant
  • Funnel
  • Operator’s Manual


4 Cycle FULL CRANK Straight Shaft String Trimmer
4 Cycle FULL CRANK Straight Shaft String Trimmer is rated 4.5 out of 5 by 1685.
Rated 3 out of 5 by from Ryobi This machine has plenty power, cranks and starts relatively easy. Is lightweight and love the bump feed system. Only down falls are, gas tank small and can't edge for more than 100ft. Trimmer stalls because it floods the machine. I have large corner lot, and need a machine that is multitask compatible. I understand that its a trimmer not an edger and that i can simply purchase the edger attachment for an extra 60bucks, but why. I owned a troy-built 4cycle trimmer for 10 years and it multitasked with no problems othe than tune-ups. My ryobi, might not be tough enough for the rugged 2hour corner lot job i do on a bi-weekly basis. Time will tell!
Date published: 2017-05-16
Rated 1 out of 5 by from Will not stay running I bought this several months ago, much to my dismay. The trimmer will stay stay running for more then 5-10 minutes. Warm starting it is a complete pain and almost never works. Took it back as it was under warranty to have it checked out. No issues. They started it up. I told them initial starting is not the problem. There was nothing they saw otherwise. I drained the oil and fuel and put new in both. Starts right up. Then dies 5-10 minutes later. Plenty of fuel and oil still. I am compressing the head trigger. It would be such an issue of the thing would at least warm start. 5 acre lore and this thing does a 1/3 at a time and quits.
Date published: 2020-08-23
Rated 5 out of 5 by from Very Powerful & quiet I really love that i don't have to mix the gas/oil. This ensures longer lasting parts in the motor. I have 1 acre of land and have killed 2 weed eaters. I am very impressed with how easy i can cut down even thick weeds and i only used less than 1/2 of the string i use when using the other weedeaters. I have not tried out the other kind of attachments that it says i can use but i'm definitely going to. It starts very easy and cleans up nice as well. I have Ryobi cordless drills/saws - i should've known to buy a Ryobi weedeater as well. I would recommend to anyone who has a big yard. It is a little heavier than the cheaper ones, but well worth it.
Date published: 2017-08-11
Rated 4 out of 5 by from Easy to use I purchased this as a replacement for the old weed-eater i had for the previous 15 years (the motor finally gave up the ghost on that one). This Ryobi is lighter than the old one and i can actually use it with a single hand. I absolutely love the feature i can use to reload the string in it. I don't have to cut two separate pieces of the line and wind it up. Just cut a single piece, stick it through the holder and rewind it. Makes it a breeze to reload. My one complaint is that it has a rather smallish gas tank. I have to fill it up twice to complete all my weed eating routine...the old one let me get just almost completed on a single tank.
Date published: 2019-07-29
Rated 5 out of 5 by from Great features I bought this a month ago. My son bought one and I was impressed when I used his; so I decided to buy one for myself. I like the fact that I don't have to mix gas and oil. The 4-cycle is less noisy than a 2-cycle and has more power at less RPM's. It will adequately cut the weeds next to the fence at low throttle; which doesn't cause the string to catch the fence as much making the string last longer. I like the straight shaft for getting under shrubs and bushes better. I will buy different attachments than what my son has; so we can share back and forth. I have 3+ acres with a lot of trees, fence, shrub etc. One tank of gas goes a long ways.
Date published: 2018-06-13
Rated 1 out of 5 by from DO NOT buy this I would not recommend this product to anyone any more. The quality control has slipped a lot on this product. RYOBI 4 cycle X430, serial # EU16041D051147, Manf # 090432020. I am a professional small engine tec & landscaper; I purchased this unit in 2016 and had a problem right out of the box. The fuel pick up tube was too short and would only run when full of fuel down to ¾ tank. Then one of the screws must of vibrated out and lost for the fuel tank, the treads were striped in the mounting location. Then the power head started to rotate on me and come off the shaft, the one set screw that keeps it in place was stripped “treads” no fix for this one. The rest could be fixed by me but the last one was not fixable.
Date published: 2017-10-11
Rated 5 out of 5 by from finally a easy refill weed wacker I have had many weed wacker in my life this is my first 4 cycle straight gas weed wacker! Never did like mixing oil and gas now thats in the past! always freated over refilling new string was a pain in the rear! but this RYOBI 4 Cycle FULL CRANK Straight Shaft String Trimmer is just what can i say outstanding just check oil add gas when you run out of string just line up holes thread string and turn handle crank (included in box) and your ready too go! very happy I purchased RYOBI 4 Cycle FULL CRANK Straight Shaft String Trimmer have done my 60 x 90 foot back yard liked it so much I drove over to my sister house and trimmed her 90 x 80 foot back yard
Date published: 2019-05-15
Rated 5 out of 5 by from THIS gets the job done quickly! I picked up the 4-cycle unit with a little trepidation. Invariably all reviews have those 1 ratings that stop and make you think. I had seen a couple on this unit, but it was by far the best rated I could find. A little higher price, but WELL worth the money. Started right up and has done so ever since. Makes my big projects (due to my small trimmers) a cake walk. We have a green way we trim along a creek. It can over grow fast. This makes taming that creek area a very easy task. Plenty of power, light enough I don't get tired and the straight shaft is much easier to use than the bent ones I've grown used to. Great product!
Date published: 2018-06-16
  • y_2020, m_9, d_23, h_15
  • bvseo_bulk, prod_bvrr, vn_bulk_3.0.12
  • cp_1, bvpage1
  • co_hasreviews, tv_102, tr_1583
  • loc_en_US, sid_300339341, prod, sort_[SortEntry(order=RELEVANCE, direction=DESCENDING)]
  • clientName_ryobioutdoortools