string trimmer problem

Bonzoso

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Jun 8, 2017
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Hi all. New guy here. I'm having problem with and older Ryobi 790r string trimmer. Amazingly this trimmer has been trouble free for many years but this year have been having trouble keeping the engine running. I rebuilt the carburetor and have been trying to get the jets tuned right. This is an older model which has access to the jets without a special tool. After the rebuild, I was able to get it started but it would not start with the original jet settings after removing the screws, cleaning, and setting them back to the original settings. Again this was a complete teardown of the carb with thorough cleaning and new gaskets, needle valve, etc. So I started from the beginning with the normal procedure of backing the High and low jets off 2 turns and then adjusting the low jet at idle and then the high. I've gone through this procedure several times and seem to get it running well for about 10 minutes, but then it starts to have problems bogging down when I hit the throttle, and stalls. I am able to start it again at idle, but again can't get it to throttle up without bogging. After about 5 minutes more, I can't get it started at all. If I let it sit for an hour or so, it will start but the same thing will happen after it warms up again. Wondering if you all think this is an ignition coil problem or what. Thanks for your input.
 

motoman

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I had a Ryobi which was great for 10 years. Started to rebuild, but the parts exceed the cost of another low end 2 stroker. I bought a Sears weedwhacker with the same engine and click stalk for around $120 on sale couple years back. Unfortunately, these great little whackers are designed to throw away. On mine I found magnet marks on the coil and tried to look at the crank, but it was a fruitless venture. The gas tank had begun to leak and the price of these two items was close to the Sears sell price.
 

Bonzoso

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Jun 8, 2017
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I had a Ryobi which was great for 10 years. Started to rebuild, but the parts exceed the cost of another low end 2 stroker. I bought a Sears weedwhacker with the same engine and click stalk for around $120 on sale couple years back. Unfortunately, these great little whackers are designed to throw away. On mine I found magnet marks on the coil and tried to look at the crank, but it was a fruitless venture. The gas tank had begun to leak and the price of these two items was close to the Sears sell price.

Thanks moto. Exactly what I was wondering. I see I can get a cheap chinese coil for about 16 bucks but that might be a crapshoot. An OEM coil costs $60 but I can buy a new ryobi head unit for $70. I put 6 bucks into the carb rebuild kit but wouldn't want to put much more into this machine than about $30 to get it running, after that, as u say I may as well get a new one.
 
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