# Ryobi cold start issues



## John O`Neal (Oct 19, 2007)

I recently acquired a 31cc Ryobi weed eater that wouldn`t start. Having read many of the threads on various forums regarding potential causes an remedies I dove in. I replaced all of the fuel lines, replaced the tank filter, pulled the clutch & fly wheel to check the key-way condition. Key-way OK. Reset the coil clearance at 10 thou. and moved on to the carb. This unit came with a Walbro WT 340 carb. I purchased a kit and tore it down. I removed the two welsh plugs and cleaned it with brake clean (did not soak carb core) reassembled using the original metering arm lever. The kit contained what appears to be an updated gasket on the pump side , red plastic as opposed to a black mesh finish. After reassembly I primed it and it fired right off. But wouldn`t stay running had to resort to re priming to get a re fire, then pumping the throttle to keep running. After several cycles of this the motor heat finally came up an the engine started running great. I adjusted the carb, idle circuit first then the high speed. Engine crisp on the throttle, idles great, you can feel the power when it revs up. Shut it off and it re-fires on the first pull. I thought I had just arrived in 2-cycle heaven. Boy was I mistaken Let this thing cool off and it`s back to the prime /choke /pump the trigger routine till the engine finally acquires some heat and starts running great again. I hope to use this engine in a long shaft weed eater marine conversion to push my duck hunting layout boat . Since this activity will occur primarily during the winter months ,cold start capabilities are a necessity. If you guys out there can help me diagnose this issue and point me in the right direction your help will be greatly appreciated.


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## hankster (Jan 1, 1998)

What plug are you using? Is it a new plug?


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## John O`Neal (Oct 19, 2007)

The plug is a Champion DJ7Y gaped at 20 thou. It is brand new and was the type of plug that came in it. The gas being used is fresh unleaded premium mixed at 32/1 as called for on the motor requirements sticker.


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## hankster (Jan 1, 1998)

That plug is correct. Could be a number of things but I'd be leaning on the carb settings. When it is hard to start, pull the plug and see if it is wet or dry and adjust the carb accordingly. Maybe only 1/8 turn to correct that problem.

The other thing to look for is if the choke is sealing properly.

Other problems could be an air leak. Once started and running (but before it is really warm) take a can of carb cleaner and spray it around the cylinder/crankcase mount and the carb mount. If the engine changes RPM then there is an air leak.

Could also be a scored piston/cylinder or a stuck ring (low compression).


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## John O`Neal (Oct 19, 2007)

Hankster ; First off thanks for your help and sharing your expertise with me. I ran the engine for 20 min. yesterday at an idle with Techron fuel system cleaner in it. Today it cold started 3 times in a row but is still finicky to keep running till it gets some heat in the engine. The plug is definitely dry so I assume its a lack of fuel flow fuel flow issue. I will try the fuel mixture adjustment route and see if I can improve the cold running problem. I am suspicious of the heat in the engine relationship. Couldn`t low compression cold also result in a low vacuum signal to the carb till till the heat in the engine comes up thus closing up the clearances and improving both compression and the vacuum signal which as I understand, affects fuel flow. (just rambling) This brings me to the question ; Can I re-ring the cylinder? If I can find a source for a new ring what is the preferred method of de-glazing the cylinder wall. Ball hone/ ridged hone/abrasive flapper, etc. How is it done , or is it even done at all on these little motors? Thanks again for your help and knowledge.


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## hankster (Jan 1, 1998)

Those engines are typically cold blooded and need a bit of warming up until they run properly. Prolly what you are seeing now is normal operation.


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## John O`Neal (Oct 19, 2007)

Hankster; Good call on checking for an air leak. The crankcase gasket was leaking. I suspect that this resulted in a weak vacuum signal to the carb thus compromising the engines ability to draw fuel into the crankcase. The interesting side of this was that the leak disappeared as the engine heat came up. The aluminum crankcase was apparently expanding as the engine warmed up closing the leak. I replaced the crankcase gasket and the cold start issues have gone away. Thanks for pointing me in the right direction.


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## hankster (Jan 1, 1998)

Glad you got it fixed.


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