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JohnF2015
JohnF2015, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1072
Experience:  Owner/Service Technician at S & J Small Engines
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I have a two year old Ryobi RY28140 trimmer that won't

Customer Question

I have a two year old Ryobi RY28140 trimmer that won't start, in fact it makes no attempts to start. Compression is 125+, new coil set to spec's, new heat dam, carburetor and all gaskets. I have worked on small engines as a hobby for over 30 years and
since retiring have a small engine repair business. I have never had one act this way it acts as though it is out of time but flywheel and key appear good. I tried getting help from Ryobi but all I have so far is wasted time and no solutions but to take it
to a service center which is over 30 miles away.
Submitted: 1 year ago.
Category: Small Engine
Expert:  JohnF2015 replied 1 year ago.

Hi, my name is***** will be assisting you.

Have you taken a look at the cylinder and sides of the piston? Your compression reading sounds good but in my experience it sounds too good. I have seen these machines with damaged piston and cylinder walls that allow crankcase pressures to bypass the sides of the piston and cylinder and give you really odd compression readings. I would remove the exhaust and take a look at the side of the piston, and maybe even remove the spark plug and try to get a look down into the cylinder walls.

Customer: replied 1 year ago.
I can pull it down and check the piston and cylinder wall since you can't see much of the piston through the exhaust and intake ports but the short block is a new take off from a unit that was damaged in shipping. The original short block had 50-60 psi with the same symptoms I am still experiencing.
Bob
Expert:  JohnF2015 replied 1 year ago.

The 50-60 on the old one is definitely an issue and I could understand it not running. I have never seen one of these that would run with less than 90 psi which being said you would think that the replacement would run since you say it has 125+ but I have seen times when the cylinder becomes damaged badly enough that it would give you false compression readings and it throws you off on troubleshooting starting/running problems.

Can you see down through the spark plug hole to be able to view the sides of the cylinder wall? You should be able to view damage from there.

Customer: replied 1 year ago.
I will pull the plug first and see if I can see the cylinder well enough to check for damage. I can't believe I am having this much trouble with this one unless I was lied to about the new take off short block, which wouldn't be the first time I have ben lied to on ebay auctions. This has become a mission rather than a cost situation, I could buy one for the time and parts costs involved in trying to repair and Ryobi has been no help.
Thanks,
Bob
Expert:  JohnF2015 replied 1 year ago.

Sometimes Ebay sellers aren't always the most honest but it very well could be a take off short block, just makes me wonder why it was taken off. I definitely understand the mission, I have had the same thing happen to me from time to time. You get way more time involved into the machine than what it is worth but it is nice to figure out the problem and once you do it helps to keep the same thing from happening again.

Customer: replied 1 year ago.
John, I pulled the plug and from I can see all looks good, the piston is clean as new. I did notice that the cylinder and plug were dry instead of being wet from priming and pulling the rope 10 times.
Bob
Expert:  JohnF2015 replied 1 year ago.

If the plug is dry then you aren't getting fuel to the cylinder. Try removing the air filter and spraying a little bit of fuel directly into the throat of the carburetor and see if it will start and run until it burns that off.

Customer: replied 1 year ago.
I tried that too after I realized the dry cylinder but all it does is sputter like it's trying to fire but out of time. I had a customers chain saw which was doing the same thing but since it was under warranty I took it to a dealer. When I picked it up I asked what the problem was and, not wanting to tell me their trade secrets, he said they adjusted the timing. I wasn't aware you could adjust the timing on a 2 cycle.
Bob
Expert:  JohnF2015 replied 1 year ago.

There is no way to adjust timing on a 2 cycle. The only thing that may have happened is the flywheel key sheared. If you haven't already done so you might want to check that. It really still doesn't explain the dry cylinder, even if you aren't getting spark at the right time you should be getting fuel all the time as long as the carburetor is functioning and the engine is pulling the fuel in. The cylinder being dry makes me go back to a damaged cylinder that is not creating the vacuum to pull the fuel in when it needs to or should be. By spraying directly into the throat of the carburetor you have somewhat eliminated the rest of the fuel system.

Customer: replied 1 year ago.
As bad as I hate to say it, with the other customer work I have, I guess I'll call it quits and have a very expensive paper weight.
Bob
Expert:  JohnF2015 replied 1 year ago.

It is very aggravating when you get these machines that give you so much trouble like this one. I have been in the service and repair business for almost 30 years and it does happen once in a while, you hate to give up on it but with all the other things that you could be doing it is sometimes better to move on to something else and then come back to it at a later time. You hate however to just keep putting time and money into it because you know that you can never get the customer to pay you what it is actually worth or what you have invested into it.

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