2-cycle woes


Old 05-13-04, 05:55 AM
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2-cycle woes

I've been trying unsuccessfully to start my Ryobi 700r string trimmer for some time now. The problems started last season when it was rather difficult to start (approx. 5 min of pulling). This season it refuses to start, or fire for that matter. The spark plug seems to be in good condition, it is getting a spark, and I have cleaned the high and low ports on the carburator and adjusted them according the the manuel (screwed them all the way down and then backed off 1 1/4 turns). On 2 separate occassions I have removed the cover to the carb and jiggled the valve (needle valve?) just underneath the cover. When I reassembled it and attempted to start it, the trimmer fired on the first pull but failed to 'catch' and continue running. On subsequent pulls the trimmer failed to even fire. Any ideas at this point?

thanks, John
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Old 05-13-04, 07:37 AM
repair_guy's Avatar
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Join Date: Apr 2004
Location: Marion,Al.
Posts: 539
Yor need at lest 75LB.compression. Check this first.
I'd take muffler off check cylinder for scars.If none,Sprad you out a rag,and disassamble the carb.all the way.Soak in chem-dip for 30-40 minutes,rinse off and blow dry with compressed air.Run small wire through all of the little holes including where asjustment screws goes.Put a new carb.kit in.Your trimmer prob.has a Walbro carb on it,most likely it a WT or WAT.Make sure you get the gaskets & diaphragms mached up and in the right places.These carb.kits has diaphragm and gaskets that will fit 2 or 3 kinds of carbs.so pay close attn.

When your ready to put the needle valve in,put return spring in the well,take the lever (with bump down.Put pin through an Put neddle valve on lever and carefully put needle in hole making sure to get bump on lever in spring.Push down with one hand and fit pin in slot.Hold and put scew in.With straight edge across carb.mettering lever should just touch.Gasket goes on first and them diapgragm (with bump down).On fuel pump side diaphragm goes on first.
emtpy and refill fuel with fresh.adjust screws as per your book.crank,let worm,adjust till sounds ok to you.

Last edited by repair_guy; 05-13-04 at 08:06 AM.
Old 05-14-04, 09:57 PM
jughead's Avatar
Join Date: Oct 2003
Location: Davenport, Iowa
Posts: 597
I think a common problem with those two cycle weed wackers is that the diaphram fuel pump goes bad. Try buying a carb kit for the engine are rebuilding the carb. It's worth a try. My wife found a weed wacker in a dumpster one time that had a simular problem, that's probably why it was thrown away. It's problem was fixed with a carb kit. The carb was located inside a plastic box, however, and was difficult to work on. If it ever stops working it may end up in a dumpster a second time.
Old 05-15-04, 03:49 AM
puey61's Avatar
Join Date: Apr 2004
Location: Upstate New York
Posts: 3,224
Goodday jphilip

If you've never gotten into a tiny carburetor or don't feel comfortable doing this, I suggest taking the carburetor, alone, into a reputable repair shop and let them recon the carb. If you were to bring it to my shop, I would charge you $12 plus parts (carb kit and new mounting gasket). You may have either a Zama or Walbro carburetor, find a shop who stocks parts for either and let them rebuild it or you can certainly do it yourself, if you please. If so, look on the carb and let us know which carb you do have and we'll advise you where to look for the model #. You can then go to your local shop and get a kit. Let us know.

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