# Ryobi 725R won't rev



## Tex Cuda (Jun 5, 2013)

Hello all. I have Ryobi 725r weed eater that is about 5 years old. It was running fine a month ago but when I went to use it last week it would start but would not rev up. It idles just fine on half choke/no choke but will not rev up. Spraying carb cleaner in the venturi while messing with the throttle makes no difference, so it isn't a fuel starvation issue. I then did the following things to attempt to resolve the problem:

1. Mixed fresh fuel and oil; no change

2. Replaced all fuel lines/primer assembly; no change

3. New champion plug, no change

4. Removed muffler and checked exhaust port for buildup. No build up (not enough to affect engine performance anyway). No change

4. Pulled carb and rebuilt with a kit, new diaphragm, gaskets, needle, etc. I removed the welch plugs and cleaned behind them as well. I also replaced the carburetor gasket and adjusted the idle and high mix screws to no avail. No change 

It idles beautifully now. But all through this it has never revved at all when I mess with the throttle. Full choke, half choke and no choke all get the same result. When I pull the throttle I can hear the pitch of the motor change due to the throttle being wide open but no change in engine speed at all. 

Could this be a problem inside the motor? Perhaps a bad reed, etc? I already have $40 into parts and if I'm looking at a hard part or partial engine disassembly then might as well buy a new weed eater. 

Thanks for looking and any ideas ya'll might have.


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## paulr44 (Oct 14, 2008)

The reed valve is behind the carburetor, and if it were a problem I doubt it would idle but you can pull the carb. to check it. A slight gap between the reed plate and the phenolic body is normal, but probably no more than 0.005" would be accepable.

There could be a vacuum leak. Is there any slime around the cylinder mounting flange? Check the cylinder bolts to ensure they're tight. Also ensure the reed plate body is tight...the screws around that piece that the carb. mounts to.

While you replaced the carb. internal components contained in the kit including the welch plugs (impressive!), did you blow out the passageways behing the plugs and the ones the mixture screws fit into? There could still be a restriction in the high-speed or progression ports.

If choke helps it, there's either a vacuum leak or a carb. restriction, that is as long as fuel delivery to the carb. itself isn't an issue.


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## geogrubb (Jul 28, 2006)

While it is running spray/dribble some carb/brake parts cleaner behind the carb and along the mating surfaces, if the engine tempo changes you have found an air leak and can take the appropriate action. have a good one. Geo


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## Tex Cuda (Jun 5, 2013)

Paul - No slime or anything. I checked the cylinder bolts and they were very tight. While I had the carb off, I used a screwdriver to lightly push the reed, it moved and snapped back with no problems that I could see. As for the carb I blew out all passages with carb cleaner through a straw then hit them with compressed air to make sure nothing was left in them. The choke makes no difference at all. 

I haven't messed with it since Wednesday when I made this post. I'll go out there tomorrow and try spraying carb cleaner around the isolator, etc to see if I can detect a vacuum leak. 

It may time to go buy an Echo and be done with it. 

Thanks for ya'lls help!

Edit: So I went out and fired up the weedeater. Still doing the same thing. I sprayed carb cleaner all around the carb, carb gasket, head gasket and crankcase. No changes at all. Didn't bog down or rev up. Playing with the throttle still makes no difference. The only thing I can think of at this point is to pull the carb and soak it overnight in Berryman's caustic carb cleaner. Maybe it has some varnish built up in the high feed passages. Thanks again!


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## paulr44 (Oct 14, 2008)

Without knowing the condition, usage etc., you have to consider units like that are built to last at what's called to durable goods index. Something like that, is probably in the 4 to 6 year range. Back in the 1980's people would bring them in, we'd tell them it would be $25 *up front *to diagnose/make an estimate which we would apply toward either the repair or a replacement unit. They'd often say, "why would I pay $25 to find out what's wrong with a $59 trimmer?" To which we'd answer, "exactly."

About 2 years ago I replaced my Tanaka trimmer, a TBC-160, it was about 25 years old. I bought a Redmax, MSRP then about $309. Mind you, I don't use it every week but I figure this one will probably last 20+ years too, it's commercial duty, straight shaft (that model Tanaka had *bent shaft, which gives you a backache*), and has more power than I need. BCZ2450T model. That's a BCZ2460TS today, and a bit more money. I paid cost, as that's one of the perks. I like Tanaka, but 2 years ago we had a limited selection of Tanaka so I went with our most popular unit given my experience repairing them.


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## Tex Cuda (Jun 5, 2013)

Yeah, I think it's time to just go buy a "good" one and be down with the throwaways. Thanks for the help!


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