Engine Ryobi BP42 Won't start

[motoman]

I have had two 2 stroker weed whackers of similar design with good luck. They are demons til they wear out. I had cleared whole lots of wet 18" grass with my first one, a Ryobi. It lasted 10 years. Synthetic oil and be sure of the mix ratio. Both wanted clean air filters. Used platinum tipped plugs.

 

[Yoram Kenig]

I have had two 2 stroker weed whackers of similar design with good luck. They are demons til they wear out. I had cleared whole lots of wet 18" grass with my first one, a Ryobi. It lasted 10 years. Synthetic oil and be sure of the mix ratio. Both wanted clean air filters. Used platinum tipped plugs.

Sorry, I am talking about the leaf blower not on the weed eater !
The Back Pack Ryobi BP42 will work for few months and then die. when you open it up all the way to the piston, you see the two rings are stuck. It happened to me 3 times already and I keep replacing the engine block as just releasing the rings will not do the trick. $ 65 each time ! Used synthetic oil all the time with 1:30 ratio initially and then moving to 1:40
Same problem already 3 times !!!
I believe it is a fault in the design of the motor by Ryobi, they should make the two rings wider and farther apart so the heat
will not burn the oil and get the rings stuck
Yoram Kenig

 

[bertsmobile1]

Sorry, I am talking about the leaf blower not on the weed eater !
The Back Pack Ryobi BP42 will work for few months and then die. when you open it up all the way to the piston, you see the two rings are stuck. It happened to me 3 times already and I keep replacing the engine block as just releasing the rings will not do the trick. $ 65 each time ! Used synthetic oil all the time with 1:30 ratio initially and then moving to 1:40
Same problem already 3 times !!!
I believe it is a fault in the design of the motor by Ryobi, they should make the two rings wider and farther apart so the heat
will not burn the oil and get the rings stuck
Yoram Kenig

Run the engine till it is nice and hot
get a trigger spray pack with a very fine spray
while the engine is running flat chat, slowly spray water into the carb air intake.
The water will turn into steam and scour the rings & cylinder walls .
About 5 to 10 minutes will be fine then let it run another 5 minutes to restore the oil film on all the moving parts.
If you can get to it removing the muffler aids the process.
back when 2 stroke premix motorcycles were very common this was a weekly "tune up" which prevented oil build up in the mufflers.

 

[gtjay]

I realize this thread is a few months old, but I also recently bought a non-running BP42 and am looking for some input. Through this forum I learned enough to decide to tear into my first small engine. Unfortunately, I didn't learn enough to not destroy the stuck rings. They were stuck and I just yanked them out, snapping them in the process, because I thought new rings would be $2 parts and readily available. Unfortunately, Ryobi only sells blocks as an assembly - for $50! I don't need the whole block assembly - just two new rings. Is there anyone out there who can tell me what size rings I need and where I can get them? I tried calling Ryobi and they were absolutely no help at all. Based on measurements with cheap calipers, I believe the piston is 40mm, and the rings are 1.5mm "tall" and 0.6mm "thick." The 0.6mm thick part is proving to be difficult b/c most rings that I see online are 1.5mm thick. When I say "thick," I mean if you lay the rings on a flat surface, that's how high they would stick up. When I say "tall," I mean if you subtract the ID of the ring from the OD.

So... if anyone knows where I can find rings OR if there is an interchangeable piston that will work with this motor that uses 1.5mm thick rings, I would be extremely grateful!

 

[bertsmobile1]

I get odd rings from Total Seal.
Not sure if they go down to that size
Rings are specificed by
Diameter of the bore it is designed to run in ( on the Ryobi spec sheet )
Width of ring ( bit that runs on the bore )
Radial depth ( length from the face that runs of the bore to the back of the ring)
then there is the material
Cast Iron, steel
the working face ( if it has one ) chrome / teflon
and finally the cross section.

Blue smokes are very fussy about rings particularly if it is a cheap 1 ring piston.

 

[gtjay]

I get odd rings from Total Seal.
Not sure if they go down to that size
Rings are specificed by
Diameter of the bore it is designed to run in ( on the Ryobi spec sheet )
Width of ring ( bit that runs on the bore )
Radial depth ( length from the face that runs of the bore to the back of the ring)
then there is the material
Cast Iron, steel
the working face ( if it has one ) chrome / teflon
and finally the cross section.

Blue smokes are very fussy about rings particularly if it is a cheap 1 ring piston.

Thanks for the response! Dumb question - where do I find the Ryobi spec sheet? All I can find is an IPL with assembly called out, but no individual parts (piston, rings, etc). I can use my cheapo Harbor Freight digital calipers to measure the width (0.6mm) and radial depth (1.5mm) but have no idea how to get the other details. It's a 2-ring piston; how precise does everything need to be for the engine to run? Sorry for the dumb question, but I'm new to this stuff!

 

[Boudreaux In Eunice La.]

50 bux is cheap for a new block. You will have a new unit that way and save a lot of time and trouble.

 

[bertsmobile1]

Thanks for the response! Dumb question - where do I find the Ryobi spec sheet? All I can find is an IPL with assembly called out, but no individual parts (piston, rings, etc). I can use my cheapo Harbor Freight digital calipers to measure the width (0.6mm) and radial depth (1.5mm) but have no idea how to get the other details. It's a 2-ring piston; how precise does everything need to be for the engine to run? Sorry for the dumb question, but I'm new to this stuff!

I won't even to try & paraphrase the experts. read this http://015ef8d.netsolhost.com/TechPage.aspx#trGaplessPistRings
Piston rings are a funny animal.
Diameters are generally specified in mm
Widths in 1/8"
Radial depth in 1/10"
Somewhere will be speck sheet, google it.
Bore will be listed as will stroke, wind speed and volume etc etc etc.

 

[Bob Ford]

I Own a ryobi BP42 backpack blower,It wouldn't start I replaced carb,ignition module,spark plug,fuel lines.Finally I pulled the block and found stuck piston rings,I broke one trying to clean it,so I installed a new block assembly.I had 70 lbs compression I now have 140 lbs.The trouble now is it idles fine but if I try revving it up it stalls immediately as soon as I pull the trigger.I am wondering if there is a problem in the muffler assembly,is there a spark arrestor I am new to this,when I had the muffler off I should have tried to blow through it but I didn't.Any Ideas why it won't rev up I tried putting the original carb back on but still had the same problem.I also tried to adjust the adjustment screws I was able to get a good idle,but nothing changed on fast idle no matter which direction I turned the screw