KB9LOR 4 #1 Posted March 4, 2011 I am in the process of rebuilding a k301AS, it says in the manual a maximum wear limit of 3.378, I am getting below that, but want to make sure of at what measurement is the point of having to bore it oversize? I want to order the piston and rings, but not sure if it needs bored .010 or .020...IF any! Thanks Share this post Link to post Share on other sites
WH nut 553 #2 Posted March 4, 2011 I am in the process of rebuilding a k301AS, it says in the manual a maximum wear limit of 3.378, I am getting below that, but want to make sure of at what measurement is the point of having to bore it oversize? I want to order the piston and rings, but not sure if it needs bored .010 or .020...IF any! Thanks If you are under the 3.378 you can go standard, but make sure you measure for out of round and taper Share this post Link to post Share on other sites
KB9LOR 4 #3 Posted March 4, 2011 I am in the process of rebuilding a k301AS, it says in the manual a maximum wear limit of 3.378, I am getting below that, but want to make sure of at what measurement is the point of having to bore it oversize? I want to order the piston and rings, but not sure if it needs bored .010 or .020...IF any! Thanks If you are under the 3.378 you can go standard, but make sure you measure for out of round and taper Thanks WH NUT....will check that taper and the out of round tomorrow, just wanted to be sure that what I was thinking was right! Thanks again! Share this post Link to post Share on other sites
sorekiwi 761 #4 Posted March 4, 2011 Sometimes you have to be a little careful with your bore measurements Brian. If your bore is worn .008", it may not clean up with a .010" overbore... Normally the bore wears more on the thrust side, so you might have .006" wear there and .002" on the other. A .010" overbore is .005" on each side of the cylinder, and if you have .006" wear on that side of the bore, it wont completely clean up. The machinist may be able to fudge it a little by sneaking the bore over a little towards the thrust side (only talking a thou or two here), but it would probably be better in this case to go .020" over and leave the centerline of the bore where it's supposed to be. Safest bet is to take it to the machineshop, have them measure it and decide how big they want to go, obtain your piston, give it to them and then get them to bore and hone the block to suit your piston. Share this post Link to post Share on other sites
can whlvr 994 #5 Posted March 4, 2011 sorekiwi said it perfectly :thumbs: Share this post Link to post Share on other sites
KB9LOR 4 #6 Posted March 4, 2011 Okay guy's, if you are checking the taper in the ore, do you measure the whole length of the bore? Or only as far as the Piston would run? The out of round is good, just wanted to be sure on the taper measurement. Share this post Link to post Share on other sites
sorekiwi 761 #7 Posted March 4, 2011 Only as far as the piston moves, Brian. There should be no wear in the part of the bore where the piston doesnt run. Actually if we want to be picky, its the area where the rings run on the bore. The piston shouldnt ever touch the cylinder walls. The marks (scores) on the top of the piston on the thrust side that you usually see on an old Kohler engine are caused by carbon, not by the bore itself. Share this post Link to post Share on other sites
KB9LOR 4 #8 Posted March 4, 2011 Only as far as the piston moves, Brian. There should be no wear in the part of the bore where the piston doesnt run. Actually if we want to be picky, its the area where the rings run on the bore. The piston shouldnt ever touch the cylinder walls. The marks (scores) on the top of the piston on the thrust side that you usually see on an old Kohler engine are caused by carbon, not by the bore itself. Thanks sorekiwi, I figured as much, but wanted verification from a more experienced person, so am off to check that puppy! thanks again! Share this post Link to post Share on other sites
KB9LOR 4 #9 Posted March 4, 2011 Well just double checked and even triple checked, got .005 taper should be .003 max and just over the max on the out of round spec, looks like it is going to the machine shop, and am going to have it checked yet again.....for verification and have it bored .020 over. Share this post Link to post Share on other sites
KB9LOR 4 #10 Posted March 9, 2011 Need more help my friends, I am in process of rebuilding my k301as, and think I got the wrong rod, the one I took out has a drilled hole towards the bottom of the rod, I ordered STD size on my parts, The manual says if it has this hole drilled in it, then it it a .010 undersize rod. Is this right? I mean, I could not tell you if it has been rebuilt, but I did not think it had been rebuilt, also I orderd the .020 over piston, the old one has the markings E P on it and a 0.25 stamped on it, any ideas on that? Thanks for your help! Share this post Link to post Share on other sites
sorekiwi 761 #11 Posted March 9, 2011 I've never seen a factory .010" undersize rod, but the manual does show a picture of the identifying hole. How does it measure? Sorry, cant help you on the piston markings. Share this post Link to post Share on other sites
KB9LOR 4 #12 Posted March 9, 2011 I've never seen a factory .010" undersize rod, but the manual does show a picture of the identifying hole. How does it measure? Sorry, cant help you on the piston markings. Don't know on the measurement on the rod, I am going to measure the crank though... Share this post Link to post Share on other sites
KB9LOR 4 #13 Posted March 9, 2011 Okay measured the crank(where the rod connects) it is measureing 1.489" now the manual is saying new 1.500"/1.4995 with a max wear of 1.499" So looks like I do need a .010 undersize rod instead of a STD rod. What do you think? any kohler gearheads want to comment? please! Share this post Link to post Share on other sites
sorekiwi 761 #14 Posted March 10, 2011 Looks like your crank has been turned .010 under before Brian. 1.500 - .010 = 1.490. BTW, you really need to be measuring the crankshaft to ten thousanths (.0001), the wear tolerance is only .0010" and calipers (especially digitals) arent really accurate at that point. Or at the very least, pick up some plastiguage and check the crank to rod clearance with that. Share this post Link to post Share on other sites
KB9LOR 4 #15 Posted March 10, 2011 Looks like your crank has been turned .010 under before Brian. 1.500 - .010 = 1.490. BTW, you really need to be measuring the crankshaft to ten thousanths (.0001), the wear tolerance is only .0010" and calipers (especially digitals) arent really accurate at that point. Or at the very least, pick up some plastiguage and check the crank to rod clearance with that. I used a 1"-2" mics to check the crank, It is in .001 increments. Share this post Link to post Share on other sites