If you hone, you could be boring the size and unless your prepared to find an oversize piston/rings set you will have a very low compression machine with clean walls.

Your engine isn't beyond hope. I just repaired a D-400 with the same problem yesterday. I cleaned the cylinder walls with a round wire brush and re-ringed the original piston after cleaning the carbon from the grooves. Its not rocket science and they will run surprisingly good with a slightly scored piston with new rings.

Search my youtube channel for the video describing the cylinder deglaze I'm talking about.....I'd link it to you, but here at work youtube is blocked.
You'll either think its hokey or genius...depends on the crowd you hang with.

 

You sure it'll work for me? Here some pics. I'd have to buy a new piston/rings. Broke 1 trying to remove it from the piston. Strange thing is the cylinder wall is not nearly as bad as the piston.

 

Strange thing is the cylinder wall is not nearly as bad as the piston.

That's because the cylinder wall is cast iron and the piston is aluminum. That piston may clean up, but if you don't like it or just don't want to try, slap a new piston and rings in it after you clean up the cylinder. If Indy says he's cleaned up pistons in that shape, I believe him. Keep us posted.:fing32:

 

IF the cylinder wall isnt to bad, clean it up a bit, get a new piston and rings and be on your merry way.

 

It's been my experience that in the Lawnboy, the piston serves as the sacrificial lamb when exposed to straight gas. Makes sense because the piston is aluminum and that cylinder has a steel liner. Pistons are cheap relative to blocks.

I recently resurrected an 8070 that had a wrist pin needle bearing that fragged and a needle gouged a deep groove in the cylinder. I applied JB weld to the gouge and smoothed it down. I even installed a used but decent piston/ring set. It runs very well.

Your cylinder is pristine by comparison.

Good Luck,

Charlie

 

Most people would scoff at what I'm going to say but,.. with that piston, you can take it to a wire wheel and clean the dickens out of it and shine it up, clean the ring grooves and re-ring it, clean the cylinder walls and off you go. You would be amazed at the improvement. I just did that to a D-400 for a guy I know who loves his D-400 but lives on a very tight budget. It looked almost exactly like that one. I'm happy to keep it going at any cost, he's happy so I am too.

If your a purist, get a new piston, rings and clean the cylinder walls.

 

I don't know who would scoff at taking a non-runner and making it good again. It's certainly good to know what we can do just to make these functional again. I find it amazing what these cylinders are capable of withstanding. The D400's that I have overhauled all had serious gouges in the pistons, but the cylinder walls were hardly damaged at all. I look at the pictures in the OMC manuals and the descriptions of different piston damage and causes and I really wonder if we can even prevent this piston gouging. The book says that this is a direct result of not enough oil, but has anyone ever taken one of these apart after 10 or 15 years and not found the piston severely scored or gouged?

 

is that a D engine? i just bought a new piston and rings for mine, not sure if I am going to fix it though. maybe i can sell them to you?

 

This is very encouraging. I'll checkout the price of rings/piston tomorrow at the local shops. Where can I look up the torque specs? I think I read somewhere the rings have to be offset a certain way to clear the ports. Is that true?

 

i got my piston and rings from Napa, ended being $50 for the piston, rings, 2 seals, and the reed plate gasket.

rings were like $9, and the piston was $27. reason it was $50 was the parts had to be UPS'ed in.

 

Thanks for the info. I had no idea the piston was still available new. Is that a Toro piston?

 

The only thing I can get for a search, is a belt.

 

Sure enough, 31 and some change for D piston (replaces 606607)
Thanks again

 

Wow! half the price, thanks ODF.