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Rebuilding 728 / engine advice needed


RipRat

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I am new to the club, and only 6 months into my Simplicity tractor addiction. I am currently restoring a Simplicity 728 Broadmoor that I purchased at a farm auction in Connecticut over the summer. I have aquired all of the parts I need, and cleaned and stripped down the chasis. I have a sign shop making me a set of new decals and I am currently working on the engine.

My questions are regarding the engine - the block is a Briggs 191701 aluminum block with the Simplicity starter / alternator on it. I have cleaned the block – aluminum paint stripper and a pressure washer works wonders – and disassembled the block. I am ordering a rebuild kit for the block, but I need more information on honing the cylinder. I am a novice in engine rebuilding, and would appreciate any information that you could provide.

Thanks in advance for any help you could provide.
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Do you have a means to measure the diameter?(incase it should be bored). If all you want to do is clean up the walls, being you already ordered the kit, just buy a hone for a drill, keep it oiled and make sure to go up and down as you hone. If there is a ridge near the top get a ridge reamer and cut it off.
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If you are just putting in a new set of rings. i would use a glaze breaking hone they sell them for different diameters they have heavy wire rods sticking out with small balls of abrasive material on the ends. just run it enough with a pistol drill to take the shine off and use kerosene for lube. move the hone in and out of the bore as it spins. make sure to push it into the bore before starting the drill and stop it before takeing it out, don;t go to deep and let the hone slide out the bottem of the bore you will ruin the hone if not carefull when your finished the bore should have a nice criss cross pattern to it wash it out with hot soapy water to get rid of the grit good luck with your project
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What does the piston look like along with the block bore. Hold off on ordering anything yet. Sometimes you can by with just a chrome ring set and valve grind.
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I have not ordered the rebuild kit yet but felt sure that I would need to. The cylinder is smooth, but has a few scratches, and I want to make sure that it doesn't smoke when I put it back together. I can post pic's of the piston - it is clean and looks good but it has some wear on the bottom sides. How do I know if I need ot hone the cylinder or just put new rings in? I have hear that new rings on an old cylinder is a mistake. Thanks for you help.
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This is just about everything you need to rebuilb small engines. I bought these all from Napa. [img]/club2/attach/ehertzfeld/enginerebuild.jpg[/img] this is a must!!! In my opinion, it's also handy for other things besides vales. [img]/club2/attach/ehertzfeld/lapping.jpg[/img] Elon
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quote:
Originally posted by RipRat
I have not ordered the rebuild kit yet but felt sure that I would need to. The cylinder is smooth, but has a few scratches, and I want to make sure that it doesn't smoke when I put it back together. I can post pic's of the piston - it is clean and looks good but it has some wear on the bottom sides. How do I know if I need ot hone the cylinder or just put new rings in? I have hear that new rings on an old cylinder is a mistake. Thanks for you help.
New rings is a good idea. I have replaced a few. As for your piston, I know others will scold me for saying this, but your not building a race car, right? Clean it, replace the rings and use it. Elon
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Hi Ray, and welcome!! You sure have gotten off to a great start around here. These guys all love to see pictures. It looks like you have a good start on your restoration project as well. As far as tips on rebuilding your engine. I think it's kinda difficult to try to talk a beginer through it in a couple of paragraphs online. However, Briggs has a couple of excellent books on the repair and maintenance of their engines. There is a lot of winter left, and plenty of time to pick up a couple of books and get some reading in. These books can often be found on ebay and from several other sources, you can probably even check them out at your local library. My suggestion, for what it's worth, would be to pick up a couple of books, get in some reading time sitting beside your engine, and then ask questions about whatever may not be clear to you. These engines are pretty basic and a lot of fun to work on. I think you will really enjoy your project. (and the others that are sure to follow)
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I agree w/ John completely. he older vertion of the Briggs manual covers everything you need to do and explains what to look for and how to deal with it all. If it's only worn a little then do as Elon suggested and rering it and go. But there again, the book covers this and how to judge when this type of repair is needed.
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I agree with elon. If it was running befor and not knoking, and did not use a large amount of oil. And you look at the ring ridge and its not to big. You should just clean up the cylinder wall with some very fine sand paper (800 to 1200 grit) moving in all directions. And maybe a light honeing, You must cut any rige at the top of the cylinder, even the smallest.If you dont you put the new ring in and the first time you fire it up the pistion will go up to the top and the top ring will ever so slightly bump the ridge and you will have not gaind a thing. Then a new set of Chrome rings. Yes you sould look at the valves and check to see if the head is true and flat. But if it was running befor, its been my experence to grind valves and plane a head is not worth it. Over honeing is to easy and if you try to hone out some small to adverage scraches you can take out way to much of the rest of the cylinder wall that is not needed. Next thing you know your honeing has add to the worn cylinder. It basiclly a judgement call, If you want to extend the life and stop some puffing of smoke and using a little oil. And to gain back some of its power. Spend $35 for some chrome rings. Within 1 to 2 hours have it running again. If you go by the book, and you see the scrach on the cylinder the book will tell you to have it bored (big$). Ok then you will need a over sized piston and rings (big$). Now you can possable spent $200, Used on Ebay 150 to $200.
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Ray here is alink someone posted awhile back you might want to read through it has alot of basics in it http://www.repairfaq.org/samnew/lmfaq.htm
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