Is it time for a rebuild?

[BBB123]

Hey guys,
Finnally got a chance to pull the head off the 100 tonight. Not sure what I'm looking at, the piston looks like its worn more on one side near the exhaust valve? I would appreciate any opinions on the condition. There is not much of a ridge at the top bit it looks pretty smooth to me. Local shop said $500-$600 to rebuild

Thanks

[olds45512]

How does it run? Does it smoke or make noise?

[BBB123]

Originally Posted by olds45512

How does it run? Does it smoke or make noise?

It wasn't making any noise but was puffing smoke out of the breather and alot on startup. It would have trouble under load, random backfire

[J-Mech]

Originally Posted by BBB123

It wasn't making any noise but was puffing smoke out of the breather and alot on startup. It would have trouble under load, random backfire

Puffing out the breather is normal. Smoke on startup does indicate wear, but if it goes away, the motor is fine. Sounds to me like you had a tuning issue. Probably time to tune up the ignition/time it, and rebuild the carb.

In the future, if you want an opinion on the condition of your engine, you need to post pics before it is cleaned up. Can't tell a damn thing with it clean. Looks shiny to me.

Make sure you plane the head before you reinstall it. The gasket was probably blown. If we had pics before cleaning, I could have told you.


Local shop's price is interesting. Either they know what they are talking about, or they don't. Or they are only quoting a short block. I'd say for that price, it won't be all assembled and test ran.

[BBB123]

Originally Posted by J-Mech

Puffing out the breather is normal. Smoke on startup does indicate wear, but if it goes away, the motor is fine. Sounds to me like you had a tuning issue. Probably time to tune up the ignition/time it, and rebuild the carb.

In the future, if you want an opinion on the condition of your engine, you need to post pics before it is cleaned up. Can't tell a damn thing with it clean. Looks shiny to me.

Make sure you plane the head before you reinstall it. The gasket was probably blown. If we had pics before cleaning, I could have told you.


Local shop's price is interesting. Either they know what they are talking about, or they don't. Or they are only quoting a short block. I'd say for that price, it won't be all assembled and test ran.

Good to know for next time, There was a ton of carbon build up. He said it would be ready to go from the shop, he does small engines on the side for cash under the table. The gasket surface on the head and block had no burn marks but I'm wondering if it's the correct gasket

[sawdustdad]

As a point of reference, I pay $250 for a shop to bore the cylinder, turn the crank, and grind the valve seats. I pay about $100 for a rebuild kit (piston, rod, gaskets and valves) from a guy on ebay. So that's $350.

Like Jonathan said, it's unlikely you're getting a quality job for that price. Maybe just a set of rings and call it done. Be sure to ask some questions about what they intend to do for that prices.

Rebuilding the engine also (IMO) involves static timing it, rebuilding the carb, planing the head, replacing the head bolts (and chasing the head bolt holes with a tap), re-shimming the camshaft, new points, plug, condenser, air filter, new fuel lines, and re-painting.

If the engine is out, you might as well rebuild the PTO clutch, and the drive line--clutch and associated components.

If you've never done it before and have basic tools, don't be afraid to tackle it. The service manuals are excellent and walk you through it step by step. I had a bad experience and paid a dealer $800 to rebuild the engine in my 108 about 5 years ago. It lasted less than 50 hours. All they did is re-ring it. I took it back and they did it again under warranty for free. From that point on, I've been doing them myself. At least I know what's going into them.

[johncub7172]

Take a good look at the Kohler Engine manual. It's going to explain the engine components, and give exact measurements. This tells the story of what needs done. You will see, with the right tool for measure, that the cylinder wears like the hour glass in some cases. My engine tech always replaces the engine governor gear no matter what, and I'm fine with that!

Good luck, please keep us posted!

[ambrola]

Originally Posted by sawdustdad

As a point of reference, I pay $250 for a shop to bore the cylinder, turn the crank, and grind the valve seats. I pay about $100 for a rebuild kit (piston, rod, gaskets and valves) from a guy on ebay. So that's $350.

Like Jonathan said, it's unlikely you're getting a quality job for that price. Maybe just a set of rings and call it done. Be sure to ask some questions about what they intend to do for that prices.

Rebuilding the engine also (IMO) involves static timing it, rebuilding the carb, planing the head, replacing the head bolts (and chasing the head bolt holes with a tap), re-shimming the camshaft, new points, plug, condenser, air filter, new fuel lines, and re-painting.

If the engine is out, you might as well rebuild the PTO clutch, and the drive line--clutch and associated components.

If you've never done it before and have basic tools, don't be afraid to tackle it. The service manuals are excellent and walk you through it step by step. I had a bad experience and paid a dealer $800 to rebuild the engine in my 108 about 5 years ago. It lasted less than 50 hours. All they did is re-ring it. I took it back and they did it again under warranty for free. From that point on, I've been doing them myself. At least I know what's going into them.

I paid 350.00 for a complete new engine K161, from a friend. That's exactly what he had in it. Good Call.

[dvogtvpe]

$550 to 6 is what I get for a running stock engine rebuild, I bore them myself, cut the seats , deck the block and head. the only outside sourcing I do is crank grinding. if I give them 3 or 4 cranks I pay $30 each to grind them. you want more power. we do that to all the way up to $7000 alky motors. anyway my point is the guy could know what he's doing. just has the ability to get it done reasonable
I know more people that take everything to the machine shop and have them do all the fitting of the piston and checking clearances take it home and "assemble " it . then piss and moan the machine shop screwed it up . assemblers usually have that problem.

[drglinski]

Dad rebuilt his 12 HP about 12-15 years ago himself. With machining and new parts it was just over 400 (and that was then.) Still going strong.