Melted Lawn Boy 10247 engine.

[OverKnight]

I recently acquired a Lawn Boy 10247 Silver Series mower S/N 220007438. After some minor cleaning and adjusting, it ran well, except it was running too fast; governor adjustment was needed, but with a service manual I wasn't sure how to do this. I tried cutting my lawn, keeping the RPM to what sounded like an appropriate level. After about ½ hour, it threw the connecting rod, damaging the piston in the process. The extreme scuffing on the piston skirt suggested inadequate lubrication. Lawn Boy specifies a 32:1 fuel:oil ratio, but I had read on this site that the newest two-stroke oils are good enough that all two-cycle engines can safely run a 50:1 ratio; this is what I use in my Echo backpack blower and string trimmer. My suspicion is that 50:1 may be acceptable for a Lawn Boy, but that I was over-revving it; maybe it wouldn't have blown at the speeds I was running it at with a 32:1 mix, but this is all a moot point.

The crankshaft, the crankshaft bearing and the crankcase appear to be undamaged. The cylinder has some minor scoring, but in my experience (albeit not recent), most two-cycle engines have some cylinder scoring which is mostly inconsequential.

M questions are:
1. Would using a cylinder glaze breaker be adequate to knock off any high spots off of the cylinder? I'm already going to have to purchase a connecting rod, needle bearing assembly, piston and rings, crankshaft seals and whatever gaskets are needed. If I also need a block/cylinder, I doubt that it's worth fixing.
2. Does anyone know where I can download get a (free) service manual for this mower? Free is best, but I'd be willing to pay for it as long as it doesn't cost too much.
3. It appears that the crankcase halves are sealed only with LockTite 6CC sealer; no gasket is used. Does this sound right?
4. Is it safe to run these engines at a 50:1 fuel:oil ratio (as long as it isn't over-revved ), or should I run 32:1, or maybe 40:1? I always use Echo brand two-cycle oil.

I'll be very appreciative of any other suggestions and advice offered to repair this mower.

[38racing]

Not sure if this will help as it does not list your model in the 'using this manual ' section
https://lookup3.toro.com/ttcgateway/acr ... lball.html

[OverKnight]

Thanks, 38racing, I'd found this also. It's not relevant to my engine but it's a good read. Section 15 - Dealer Section - Aids and Shop Hints was removed because it supposedly is no longer applicable, but for a historical perspective this would have been an interesting section to see.

[KE4AVB]

This should be the service manual you need. Not free but sometimes you need to purchase one any way. Reasonably priced @ 9.95 usd.

Lawnboy-walk-behind-mower-21-22-inch 1990-2006

[OverKnight]

Thanks, KE4AVB, for $10.00, I'm in. However, after submitting the payment for the PDF file, what was downloaded was the Toro/Lawn Boy Walk Behind Power Mower Drive System manual; definitely not what I thought I'd purchased, and definitely not what I need. I'm sure it's just a matter of the seller posting an incorrect download link. I've contacted the seller for either a corrected download link or a refund. I'll let you know what happens.

[KE4AVB]

Hope they will as haven't any problem download manual dorm them but it this case I have only seen one Lawnboy mower and it was already way pass any repairs. The way describe it it was a full service manual which would what I would looking for myself if I was needing a manual.

[OverKnight]

The seller responded with an apology. He asked for the model and serial numbers of this mower so he could get the correct manual. Couldn't ask for more.

[OverKnight]

The seller sent another Dropbox link, but none of my browsers liked how the security certificates were configured, and I couldn't download the file. I asked the seller for a more secure link, or to email me the PDF file directly to me. This is what they did, so it all worked out well.

Back to one of the original questions: would it be acceptable to use a glaze breaker to try to smooth the cylinder out a little? It's been quite a while since I've worked on a two-cycle engine, and I know that's not the purpose of a glaze breaker (and I'd probably ruin the stones), but I'd just like to get it running again. If this was a mower I really liked and planned to keep for a long time, a short-block is the proper repair, but this mower was given to me for free and I was hoping to clean and tune it up and sell it. I know it won't have the same compression as a perfect cylinder, but when I worked on two-stokes as a kid (more years ago than I care to admit), I recall many having some cylinder scoring, but they ran fine; I'm hoping this will be the case here. I'm hoping to find a used piston and connecting rod, or if I'm really lucky, a decent used short block. My gut says this is probably a lost cause, but because everything else about the mower is in great shape, it would be a shame to junk it. Perhaps it could be sold as is for parts.

Thank you.