I am planning on rebuilding my cc 104 engine. It doesnt run very good any more. I am pretty sure the rings are just about shot. It will start great, and run great when it is cold. When it gets warm it starts running realy rough and wont run very long in third gear. It stalls out if I try to go up too steap of a hill. I was wondering how much I could over bore it and what size piston and rings I will need.
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CC 104 engine overhaul
- Thread starter 48 cub
- Start date
gitractorman
501 Club
Actually, it sounds like you have burnt or carboned up valves. I would buy a head gasket, pull the head, clean everything, use some carb cleaner to clean the valves and make sure they're moving freely, and re-assemble. If it's running good when cold, and not using much oil, valves are the likely culprit, and VERY common in old Kohler engines. It's worth the $20 for a head gasket to give it a try. Otherwise, you're looking at several hundred dollars to bore and do a complete rebuild. Locally here, I use a NAPA shop where a guy is known for rebuilding Kohler engines. He charges $75 + Parts to bore out, install new piston, re-install crank and bearings, and install new valves. Typically, parts included, this ends up being about $200, +/- $50.
Another thing to check is the coil. If a coil is worn or incorrect, they can overheat and stop producing spark at the strength they should. It's another common problem when someone has swapped out a coil and use a non resistor coil where a resistor coil is needed. They all look the same, and people all think they are the same, so it's not a suprise to find the wrong one installed. An overheating coil will produce the exact kind of running that you are experiencing.
Just some thoughts, found out the hard way.
Another thing to check is the coil. If a coil is worn or incorrect, they can overheat and stop producing spark at the strength they should. It's another common problem when someone has swapped out a coil and use a non resistor coil where a resistor coil is needed. They all look the same, and people all think they are the same, so it's not a suprise to find the wrong one installed. An overheating coil will produce the exact kind of running that you are experiencing.
Just some thoughts, found out the hard way.
Coincidentally my 104 is getting pretty tired too. It's had some piston slap for many years but has always run strong and never used any oil. Now it has very little power after it's thoroughly warmed up (one might even say "hot") and has some blowby coming out beside the cooling fins where the vent hose connects to the carb. ..so it's due for a teardown and rebuild I'm sure.
I just recently put a new head gasket in it after burning a hole in the old one. I know that the rings are going bad and it burns oil. The valves may be part of my problem, it started with not wanting to stall out in mid throttle when cold. Then I started mowing a field of thick grass and it started running rough. I know I could just put some new rings in it but I want to give it some more power. I plan on getting it bored or hoaning it to fit a bigger piston. I figure if I'm going to rip it apart I might as well make it worth wile.
I wouldn't go with a bigger piston unless you need to get the cylinder "round" again. The power you will gain from going .010 oversized is minimal. Think of it - standard sized piston is 3.251 inches. You are going to increase its size to 3.261 inches - how much more displacement did you really add?
If I were rebuilding it I would go with a new piston and rings instead of just rings even if it is standard. Some people don't like this supplier but I've had great luck with him
http://www.ebay.com/itm/fits-Kohler-Eng ... 5894697fde
Gasket kit with new piston and rings - $55.
http://www.ebay.com/itm/Engine-Rebuild- ... 20c664b6ad
$77 for a complete gasket kit, rings, rod and piston with a tune up kit. For $28 more you can get the kit with new valves. I just ordered one for a K301 without the rod and with the piston .020 oversized - everything measured up as it should. This will be the 5th engine I gotten parts for from him.
If I were rebuilding it I would go with a new piston and rings instead of just rings even if it is standard. Some people don't like this supplier but I've had great luck with him
http://www.ebay.com/itm/fits-Kohler-Eng ... 5894697fde
Gasket kit with new piston and rings - $55.
http://www.ebay.com/itm/Engine-Rebuild- ... 20c664b6ad
$77 for a complete gasket kit, rings, rod and piston with a tune up kit. For $28 more you can get the kit with new valves. I just ordered one for a K301 without the rod and with the piston .020 oversized - everything measured up as it should. This will be the 5th engine I gotten parts for from him.
It should only need to be re bored if the cylinder is measurably out of round - then it will need to be bored out to the next size - usually .010 oversized. If its been terribly abused and beaten up a machine shop may go .020 or even .030 to get rid of all the scarring in the walls of the cylinder. The last K301 I did (before this one) had a .010 oversized piston in it but must have seen a lot a wear because it was out of round again and I had to go .020 for the new piston.
The current one I'm working on already had a .020 oversized piston and was still within spec. I simply replaced the piston with another .020 over sized piston. The one I pulled showed abnormal wear in the piston skirt for what little time it must have been used (the cylinder walls still had hone marks in most places it was possibly a used piston from another engine that was dropped in.
On a K321 I overhauled years ago the cylinder measured "standard". All it needed was to be honed (removes glazing on cylinder walls) before I installed a new piston and rings. Honing is as important as replacing the rings when you have the engine apart. Replacing the rings and not honing the cylinder will have unfavorable results - usually lots of oil burning. The same if you only hone the cylinder and reuse your old rings. Replacing the piston is a matter of choice. If I've taken the time to completely tear down and engine I usually go with a new rod and piston to go with the rings. Some people get perfectly acceptable results just putting in new rings - but I doubt I would be one of them.
The current one I'm working on already had a .020 oversized piston and was still within spec. I simply replaced the piston with another .020 over sized piston. The one I pulled showed abnormal wear in the piston skirt for what little time it must have been used (the cylinder walls still had hone marks in most places it was possibly a used piston from another engine that was dropped in.
On a K321 I overhauled years ago the cylinder measured "standard". All it needed was to be honed (removes glazing on cylinder walls) before I installed a new piston and rings. Honing is as important as replacing the rings when you have the engine apart. Replacing the rings and not honing the cylinder will have unfavorable results - usually lots of oil burning. The same if you only hone the cylinder and reuse your old rings. Replacing the piston is a matter of choice. If I've taken the time to completely tear down and engine I usually go with a new rod and piston to go with the rings. Some people get perfectly acceptable results just putting in new rings - but I doubt I would be one of them.
When the cylinder bore/wear is measured, be sure a measurement is taken at the bottom of the cylinder or piston stroke also. There will be more wear (egg shape) there, even if the top of the cylinder has little or no wear, and that will determine how much it may need to be bored. The K series Kohlers seem to "egg shape" the bore more so than other engines do. How long it would take to bore it will depend on the machine shop that does the work. The actual process does not take long, but unless the shop has nothing else to do, it is not something you can drop off and wait for them to do, like you would for an oil change in your vehicle.