857lover 291 #1 Posted March 2, 2022 (edited) looking to rebuild the k181 on my 857 and i was wondering how much power would going .30 over and using a +.10 rod add to my machine i know it won’t be crazy but i’m just looking for someone with more knowledge and i can’t seem to find a compression ratio of a stock kohler 181 anywhere Edited March 2, 2022 by 857lover 1 Share this post Link to post Share on other sites
Howie 899 #2 Posted March 2, 2022 A .010 rod adds nothing power wise just tightens up clearances at the crank pin. The only power a .030 piston will add is because compression has been restored. Well maybe a tiny bit because of the slight overbore. Just my opinion! 1 Share this post Link to post Share on other sites
Achto 29,388 #3 Posted March 2, 2022 No gain at all with a .010 under rod. Maybe a 2 to 3 percent gain in power by going .030 over on the piston. Not enough gain to notice. 4 Share this post Link to post Share on other sites
oldlineman 1,537 #4 Posted March 2, 2022 Plus if you go .030 over when .020 or .010 would have corrected the cylinder, you would remove any future rebuilds from happening. Bob 2 Share this post Link to post Share on other sites
Achto 29,388 #5 Posted March 2, 2022 56 minutes ago, oldlineman said: Plus if you go .030 over when .020 or .010 would have corrected the cylinder, Just a note, I'm currently working on a K181 .020 over pistons seem to be no longer available. Bums me out cause .020 would have cleaned up my cylinder but I have to go .030 over due to availability. 1 Share this post Link to post Share on other sites
oldlineman 1,537 #6 Posted March 2, 2022 That seems strange that .020 is not available. Bob Share this post Link to post Share on other sites
squonk 43,779 #7 Posted March 2, 2022 Some of the small block Kohler stuff is starting to disappear. Look up a Crankshaft for a K181. 1 1 Share this post Link to post Share on other sites
WHX?? 51,732 #8 Posted March 2, 2022 3 hours ago, Achto said: Just a note, I'm currently working on a K181 .020 over pistons seem to be no longer available. Bums me out cause .020 would have cleaned up my cylinder but I have to go .030 over due to availability. That is a bummer. This is the guy i got all my kits from guessing you checked already tho. 1 Share this post Link to post Share on other sites
Achto 29,388 #9 Posted March 2, 2022 (edited) Last time I checked he did not have them. https://www.ebay.com/itm/380462505345?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D237351%26meid%3Dd00fdbe27e114f468662d332208ed7e3%26pid%3D101224%26rk%3D2%26rkt%3D5%26sd%3D144439838108%26itm%3D380462505345%26pmt%3D0%26noa%3D1%26pg%3D2047675%26algv%3DDefaultOrganicWeb%26brand%3DKohler&_trksid=p2047675.c101224.m-1 Edited March 2, 2022 by Achto 1 Share this post Link to post Share on other sites
