General Product Question
this is for Eugene and karla.
Ryobi s430 4cycle...
General Product Question posted November 1, 2015 by robert smith
822 Views, 3 Comments
Question:
this is for Eugene and karla.
Ryobi s430 4cycle weedtrimmer. good compression, new carburetor, new spark plug, ignition coil is good, pcv valves all check, valve lash set @ 7thousandth's, timing belt is good, cam bearing in good condition so the valves open and close accurately. upper cylinder is clear of oil. but this engine will not even threaten to fire. my time is up on this unit as I can't exceed a small repair bill for a tool with little market value. the positive and negative pressure within this crank appears to be there for vacuum and yet I get nothing. got any ideas on what is happening?
Ryobi s430 4cycle weedtrimmer. good compression, new carburetor, new spark plug, ignition coil is good, pcv valves all check, valve lash set @ 7thousandth's, timing belt is good, cam bearing in good condition so the valves open and close accurately. upper cylinder is clear of oil. but this engine will not even threaten to fire. my time is up on this unit as I can't exceed a small repair bill for a tool with little market value. the positive and negative pressure within this crank appears to be there for vacuum and yet I get nothing. got any ideas on what is happening?
Answer
Robert,
RY34441 (S430 Straight Shaft)
There isn't a whole lot that we can do with these as far as repairs. With you being a repair tech take the following with a grain salt; although, some it can be easily overlooked.
About all you can check is basics which is the same as any 2 cycle:
Is it getting the correct amount fuel? If the plug is dry try little induce fuel to see it will even hit. If wet remove carb and see if it hit after a few pulls. Those rotary carbs are non adjustable and very picky to repair. (Since you have already replace the carb, this one can be ignored)
Is the ignition timed correct? I have seen several flywheels with built in keys to be sheared where the clutch isn't torqued correctly.
Valve timing is fairly simple to check and time. The cam has a natural home position with the belt off between end of the exhaust and the beginning of the intake strokes. Then with the piston set TDC reinstall the timing belt.
Do you have spark? If not then disconnect the coil kill wire and try.
Is the muffler free flowing?
The following is just my opinion and other may have better experiences with these:
These engines are nothing but trouble from not being easy repair point in my opinion. Since there is no internal repair parts that are available I don't even waste my time trying to fix these any more. I did disassemble one engine's crank so I could get the piston out to clean the piston rings. Btw that only way you can change the timing belt. You got to press the crankshaft apart and remove it. Even after I got that engine to running again the camshaft bearing failed a month later; bad oil leak. Of course this unit was being used in commercial nursery operation.
I rank these Ryobi/Homelite engines in the same class as the MTD versions. They run very well until the PNC fails and then it cost more to repair then they are worth. Personally the only 4 cycle handhelds that I seen that are reliable is the Stihl 4 cycle version that uses the 2 cycle mix. Many of the Stihl owners don't even know they are 4 cyclers.
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Robert,
I do not have much experience on a Ryobi 4 cycle, I have worked on their 2 cycle weedeaters and that's usually a carburetor problem.
I didn't see anything in your list about checking the exhaust port, So I like Eugene's suggestion to check the muffler. I did recently repair and tuneup a stihl weedtrimmer, and yup it had a completely plugged exhaust port, except for a hole the size of a pencil point.
My guess probably the exhaust port is plugged but it should still have started and fired, It just won't run with a plugged exhaust port.
OK & I hope you find the problem,
Karla
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Karla,
I have seen these spark arrestors so plugged with carbon that engine can't even start. I have a lot problems with Stihl engines especially those using the round arrestors to plug up.
Another thing that can plug up the exhaust is those small mud dubber wasps. I even had customer sit his blower down to do errands to only come back to find his blower no longer would start. In my area these wasps are pest and half when comes anything under a quarter diameter. I usually need to cap off any hose that not in use to prevent them plugging them. I even had a Briggs engine blowing out the oil seals because one had plugged the crankcase vent line.
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