Engine Ryobi BP42 Won't start

1947mitcheb

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I recently bought a used Ryobi BP42 backpack blower. It will not fire. I have tried numerous things to get it started including the following:
new carburator
new gas
starting fluid
Checked to make sure sparkplug fires - it does.
replaced sparkplug

I can't get the blower to fire at all.
I already have about $100 in this blower. A new one costs about $200 so I can't afford to throw more money on labor to fix this blower. I am pretty handy and can follow instructions pretty good. If someone has some suggestions other than the one my wife gave me (throw it away and buy a new one), I would certainly appreciate your help. This unit looks like a new machine, but will not start.
 
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motoman

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mitch, I know the feeling of approching the parts cost point of no return. Try reviewing the spark threads by searching this forum. Visual spark may not mean that much. See poor man's spark tester.
 

Carscw

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Ryobi has bad coils.
I have many units with bad coils.
Sent them a email a while back and they sent me a case of coils.
 

hot pipe

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hey mitch...think its deeper then that for you brother.sad to say...
i my self just purchased the ryobi pb42 back pack leaf blower would not start..
1.removed carb cleaned 5 times
2. checked for spark OK!
3.removed flywheel check to see if key way was broke..that was ok too
4. checked clearance for coil .014 ok too
5.last on the list was to remove the block disassemble it only other thing i could think of was: bad piston rings, connecting rod bearings or even crank bearings.

so after removing muffler i rolled the motor by hand and watch the piston reach bdc bottom dead center. to find the piston was scored and the rings were stuck..so removed the lower 4 crank cover bolts(NOTE) HEAT THE BLOCK BEFORE REMOVING BOLTS they used red lock tite on the 4 cap bolts..handheld LP torch works fine... removed cap and crank rod piston assemble... and piston damaged and rings stuck in the groves...so for a few hours i used a razor knife and a flat blade screw driver to remove the bad material from the piston ring area above the ring and below the ring until it was free...did this to both upper lower rings...once rings are remove used a pocket size flat head screw driver to clean the ring groves...reinstalled the rings to check for free play in them..once that's done with both ring groves.. i then removed the rings again... next i work on cleaning the piston skirt up with sand paper 340 grit i think..till i got all the high spots off the piston skirt..yes there are groves in the skirt from the damage but its the material that is raised you want to remove...so after i got it knocked down..i used some 600 grit wet sand paper to smooth things out. used carb clearing for final clean up.used 2 cycle oil to lube everything up...and also ran the 350 grit sand paper up and down the inside of the cylinder to remove build up and burrs from the aluminum build up of the piston...reassembled engine used hi temp silicone for the lower crank case cover.
hope this helps put mine back together today. fired right up! ran it for a few hours ran 2 tanks at 32-1 fuel oil mix for break in re seating the rings
have to say though not sure how long this will last..while running it thru the first tank i was getting to hot...sad to say its in the upper 40s here in mi. let it cool for about 15 minutes strapped it back on same thing again running to hot..let it cool again before finishing up what i was doing.. but it still running...sad to say on disassembling the motor..top of piston look like it was never ran.. like little to no sign of carbon on top of piston...guessing a store return.
 

hot pipe

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any way to run these bp blower any cooler? bought it used would start. rebuilt car has good blue spark. seem to be lacking compression so tore it completely apart found piston scored and rings stuck to piston...got the rings freed up and removed cleaned the piston skirt up and ring groves cleaned up the cylinder used 2 stroke oil when reassembled. mixed fuel to 32:1 ratio let it run for about 10 minutes before putting it to work today. ran it for about an hour and it seem to be getting over heated..temps out side was in the 40's and i richin the fuel mixture on the h side a 1/2 turn. after running it a half hour it seem to be bogging. and wanting to die at a little over 1/2 throttle so let it cool for 15 minutes and proceeded to finish yard work...did it again around 45 minute to an 1 hour in to work mode...let cool again. finished the yard work 15 minutes later.
so from disassembling the machine i noticed the flywheel did not have cooling fins on it like most other 2 stroke and 4 strokes do...so there is no air moving around in the engine compartment to cool the engine... any sugestions?
 

motoman

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hot pipe, See if you can flash your motor with an infrared temperature gun or something. Why do you think it is too hot, from previous experience or heat coming through to your back? Also I use the synthetic 2 stroke oil. Poulan has reissued their brand in WalMart. I think the stuff is good for an extra edge in these little 2 strokers turning 7 grand.
 

rossfree

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Re: Ryobi BP42 Won't start - Solved! Rings Frozen!

HI all,

I just signed up on this forum so I could share.

I own a BP42, only a few seasons old. Went to start it and nothing. Replaced the gas, checked but did not replace the spark plug, sprayed starter fluid into the carb... nothing worked. Not a single hit from the engine.

I purchased a spark tester as mentioned in a previous post and put that inline with the spark plug. I appeared to have spark. I had compression but concluded that maybe it needed to be better. If the carb was bad, I still should get a hit from the starter fluid. Never once did I get a hit. The spark plug showed little to no sign of use, no carbon build up, no ash, no nothing. I assumed the tester was telling me it was firing. I looked for a spark arrester (screen) on the exhaust pipe. None found and blowing through the pipe showed no resistance.

So I took it all apart. Pain in the butt but not really. Had I known what I know now, I could have saved a few steps. Anyway. The piston comes out with the crankshaft. Four cap-head bolts and the crank case opens up. Then I pulled the piston connected to the crank. There is no head to pull on this engine.

The piston looked good. No scoring in the cylinder. But the rings were frozen in place. I pulled the piston pin and removed it from the rod so I could work on it easier. I soaked and pulled at the rings, got half loose but the other half of each ring was stuck but good. I didn't have patience for this. Anyway, I slipped an exacto blade under one end of a ring and slowly worked it under the ring, working it out of the groove. It worked. The rings were a smudge out of round but screw it. I was ready to toss this in the garbage twenty minutes before.

I cleaned the grooves, cleaned the carbon off the rings, lubricated and reassembled the rings, pistons, piston pin and crank case. The piston with loose rings went back into the cylinder easy. There is a nice taper to help you into the cylinder from the crank side. I used a bit of silicone sealant on the crank case mating surface as I went back together. Finished reassembling the machine and it started on the second pull!

I ran it wide open around the house for the next two hours. Had to stop and refill the tank. Started right back up.

When you think about how a 2 cycle engine works, it is no wonder the starting fluid would not work. The fuel is first sucked into the crank case (not the cylinder), then it is pressurized during the piston exhaust stroke. That pressure then pushes the fuel into the the cylinder at the tail end of the exhaust stroke. The rings have to work in both directions, compressing the crank case on the down stroke and compressing the cylinder on the up stroke.

In conclusion, If you think you have spark, haven't flooded it, and can't get it to fire at all, even with starter fluid, then I would suspect the rings being fouled or stuck. You may think you have decent compression but it should fire with starter fluid if you have both spark and compression. If it doesn't, then I would suspect the rings.

I hope this helps someone!

Cheers!

Ross
 

Yoram Kenig

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Re: Ryobi BP42 Won't start - Solved! Rings Frozen!

HI all,

I just signed up on this forum so I could share.

I own a BP42, only a few seasons old. Went to start it and nothing. Replaced the gas, checked but did not replace the spark plug, sprayed starter fluid into the carb... nothing worked. Not a single hit from the engine.

I purchased a spark tester as mentioned in a previous post and put that inline with the spark plug. I appeared to have spark. I had compression but concluded that maybe it needed to be better. If the carb was bad, I still should get a hit from the starter fluid. Never once did I get a hit. The spark plug showed little to no sign of use, no carbon build up, no ash, no nothing. I assumed the tester was telling me it was firing. I looked for a spark arrester (screen) on the exhaust pipe. None found and blowing through the pipe showed no resistance.

So I took it all apart. Pain in the butt but not really. Had I known what I know now, I could have saved a few steps. Anyway. The piston comes out with the crankshaft. Four cap-head bolts and the crank case opens up. Then I pulled the piston connected to the crank. There is no head to pull on this engine.

The piston looked good. No scoring in the cylinder. But the rings were frozen in place. I pulled the piston pin and removed it from the rod so I could work on it easier. I soaked and pulled at the rings, got half loose but the other half of each ring was stuck but good. I didn't have patience for this. Anyway, I slipped an exacto blade under one end of a ring and slowly worked it under the ring, working it out of the groove. It worked. The rings were a smudge out of round but screw it. I was ready to toss this in the garbage twenty minutes before.

I cleaned the grooves, cleaned the carbon off the rings, lubricated and reassembled the rings, pistons, piston pin and crank case. The piston with loose rings went back into the cylinder easy. There is a nice taper to help you into the cylinder from the crank side. I used a bit of silicone sealant on the crank case mating surface as I went back together. Finished reassembling the machine and it started on the second pull!

I ran it wide open around the house for the next two hours. Had to stop and refill the tank. Started right back up.

When you think about how a 2 cycle engine works, it is no wonder the starting fluid would not work. The fuel is first sucked into the crank case (not the cylinder), then it is pressurized during the piston exhaust stroke. That pressure then pushes the fuel into the the cylinder at the tail end of the exhaust stroke. The rings have to work in both directions, compressing the crank case on the down stroke and compressing the cylinder on the up stroke.

In conclusion, If you think you have spark, haven't flooded it, and can't get it to fire at all, even with starter fluid, then I would suspect the rings being fouled or stuck. You may think you have decent compression but it should fire with starter fluid if you have both spark and compression. If it doesn't, then I would suspect the rings.

I hope this helps someone!

Cheers!

Ross

I did the same, but still could not get it to start so went ahead and purchased the whole new engine block - it started immediately and ran well for two months.... then same thing - the rings get stuck , not enough compression and engine wan't start again
so I wonder is this a flaw in the design of the engine ?
May be it gets too hot there and causes constant ring failure ?
Any one tried this more than once ?
Thanks
Yoram
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bertsmobile1

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Are you using synthetic oil ?
A lot of the new engines require synthetics in a very lean mix.
Sticking rings are a symptom of overheating and/ or too much oil.
 

Yoram Kenig

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Are you using synthetic oil ?
A lot of the new engines require synthetics in a very lean mix.
Sticking rings are a symptom of overheating and/ or too much oil.

Yes using synthetic oil
I believe it is a flaw in the Ryobi engine design as the two rings are too thin and the fact that it happens ( by many other cases and people ) proves that there is something wrong
I believe they should move to a thicker ring size, or replace the two thin ones by one thick ring

Yoram
 
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