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Discussion Starter #1
So, I rebuilt a guy's Lawn Boy 10201 V-series...(I know, that was the first mistake). New piston & rings, new main bearings, new seals, etc. I was getting it adjusted and broken in and suddenly "SQUEAK...BANG"...No power. Not good. The rope wouldn't pull and you can barely turn the engine over from the blade end. I pulled the spark plug to look in the hole and what I found is ugly. There is a huge gash in the bore from the intake port up about 1/16" deep and at least an inch long. It looks like a piece of the top ring broke off and got jammed between the piston and the bore...probably what the squeaking noise was. I sent a message to the company I got the piston and rings from. Maybe they had a bad batch. Most likely they will tell me that I broke it. So now, I am stuck replacing at least the block to get this guy's mower back to him. Anyone have a good V-series block they want to donate???
 

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So, I rebuilt a guy's Lawn Boy 10201 V-series...(I know, that was the first mistake). New piston & rings, new main bearings, new seals, etc. I was getting it adjusted and broken in and suddenly "SQUEAK...BANG"...No power. Not good. The rope wouldn't pull and you can barely turn the engine over from the blade end. I pulled the spark plug to look in the hole and what I found is ugly. There is a huge gash in the bore from the intake port up about 1/16" deep and at least an inch long. It looks like a piece of the top ring broke off and got jammed between the piston and the bore...probably what the squeaking noise was. I sent a message to the company I got the piston and rings from. Maybe they had a bad batch. Most likely they will tell me that I broke it. So now, I am stuck replacing at least the block to get this guy's mower back to him. Anyone have a good V-series block they want to donate???
I might have one. I'll check the garage tomorrow. :fing32:
 

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Discussion Starter #3
I might have one. I'll check the garage tomorrow. :fing32:
Thanks. I tore the engine back down and found a piece of ring in the bore once I got the piston out. It broke off the END of the top ring and just destroyed the block. It actually cracked the new piston. This sucks. It wouldn't be so bad if it were my own mower, but now I'm responsible for my neighbor's trashed mower that I toasted.
 

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OMC & Ariens lover!
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ouch......i would of told the customer what just happened is why no one liked the V,usually that works along with tecumseh engines.
 

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Discussion Starter #5
I never understood what made the V so bad! It's F internals in a different block with a cheaper muffler. Why did they suck so bad? At least this one has a Walbro carb because it's a 1993.
 

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Discussion Starter #9
At least the guy understood the situation and didn't flip out!
 

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Atleast it's fall and not peak mowing season.
 

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OMG I got another LawnBoy
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I have a good mower I was going to sell, it has a crap carb, new seals and reed...really good compression. If you strike out I will sell it to you. I will sell it for what I have into it, no more.
 

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If you were closer to WI, I'd give you a complete 10301 for parts. I bought it as a parts machine since I needed a CDI pack, and it was cheaper to buy this whole mower than to buy a new pack.

If all else fails, I could probably strip it down and UPS the short block to you. Just cover the freight.
PM me or email [email protected] Email goes straight to my BlackBerry, so that would get the quickest reply.
Better yet, if you have a BlackBerry, just BBM me at 324AACE6.

Let me know... I'll do what I can to help.

-Mike
 

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Discussion Starter #13
No luck yet on finding a block. I maye have to take one of you guys up on your offer to send me a short block or something.
 

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I don't know about the Lawn Boy's, but the 2 cycle pistons I've seen have pins in the ring groove to keep the rings from rotating. But the pistons have an exhaust side. If the piston is installed backwards, then one or both ring gaps are going over a port hole which spells trouble. Not trying to insult your intelligence, just giving you a heads up in case you don't know. Sorry to hear about your situation.
 

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Discussion Starter #15
The only Lawn Boy engine with the ring groove pins are the Duraforces. All the engines have a top and bottom, and this one was installed correctly with the "BTM" casting toward the exhaust port.
 

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Did you check the ring end gap before installing? I just had an old two stroke dirtbike self-destruct in a nearly identical manner. The parts bike it came with was missing it's rings, but was also a larger overbore. I'm thinking the previous owner replaced the rings with larger ones, and since it also had a spark issue he never got it to run to destroy it.
The rings expand as they heat up, and of the gap isn't sufficient, the ends will meet and self destruct. It sounds like your piston and ring set came from an aftermarket source, so the rings were likely not fitted at the factory for the bore size.
 

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Discussion Starter #17
I did not check ring gap. I have never checked ring gap in any mower engine I have rebuilt. The Lawn Boy service manuals don't mention checking end gap, so I never have. I would imagine that if there was not enough gap, it would have been tough to get the piston into the bore. Since these engines don't have a removable head, it has to go up through the bottom and there's not enough room for my ring compressor. There are reliefs cut into the bottom of the sleeve that allows your thumb and index finger to act as a ring compressor. It went together just as it should, so I don't think the gap was an issue...but you never know. I don't think heat was an issue either. It didn't run long enough to get hot. The first run after the rebuild was about 3-4 minutes. I let it sit for a while, adjusted some things and fired it back up. Within 10 seconds or so, it exploded. I can see ring expansion being a problem if it gets hot, but it was merely warm.
 

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Discussion Starter #18
I still haven't gotten an update from the supplier of the piston and rings, so I guess I'm on my own. The owner decided to just scrap the mower and save a few parts anyway.
 

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LAWN-BOY-AHOLIC
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Sounds like a ring gap problem or possibly something getting in the crankcase that moved up into the cylinder through the transfer ports and did the deed. I had a piston pin cir-clip come out of it's groove on a motorcycle engine once that did similar damage. Believe it or not the gouge was at or below the top of the exhaust port height on the transfer port side so I just honed the cylinder and installed a new piston and rings and the thing ran like a champ.
 

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Discussion Starter #20
With the help of a member on this forum, I now have another short block to get this mower back together and make the customer happy again. Thanks, Mike!
 
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