Hossenfeffa 49 #1 Posted February 1, 2015 Looking to get a little more oomph from my K301 12 horse kohler,for running my 42 inch snow thrower. Thinking of milling .040 or .050 off the head for a little more compression. Has anyone done this, and are there any adverse effects? Share this post Link to post Share on other sites
slammer302 2,155 #2 Posted February 1, 2015 I know if you bump up the compression to much you won't be able to use pump gas Share this post Link to post Share on other sites
wheel-mule 46 #3 Posted February 1, 2015 (edited) That's a lot to mill off.Might make the compression too high for starter to turn over,plus I'm not sure but the valves might hit the head also..020 -.025 shoulb be plenty. Edited February 1, 2015 by wheel-mule Share this post Link to post Share on other sites
slammer302 2,155 #4 Posted February 1, 2015 I think you could also look for a older style LP head there supposed to raise compression to Share this post Link to post Share on other sites
oaktown1987 82 #5 Posted February 2, 2015 U can run 93 Sent from my iPhone using Tapatalk Share this post Link to post Share on other sites
Theroundhousernr 589 #6 Posted February 2, 2015 A friend of mine milled a head so far on a 16 kohler it smashed the spark plug gap to almost 0 once the pull was over. Valves never touched the head. I believe he either put a spacer on the plug or thicker gasket. Share this post Link to post Share on other sites
oaktown1987 82 #7 Posted February 2, 2015 On an lp head no mods nessacary for a 10 or 12 just need to run 93 octane Sent from my iPhone using Tapatalk Share this post Link to post Share on other sites
Theroundhousernr 589 #8 Posted February 2, 2015 (edited) On an lp head no mods nessacary for a 10 or 12 just need to run 93 octane Sent from my iPhone using Tapatalk The compression ratio is just not there to make use of 93 octane. Increasing fuel octane would be very little difference if any at all. Good air flow, such as minor porting (machting gasket surfaces and deburring). Strong compression( which major milling on head on worn out rings is not the best). Suggest honing the cylinder and new rings at the least before milling head to far. Good spark to burn the fuel properly. And then maybe you would have the need to increase fuel octane..... But even after all this, dont expect big twin power. But will very much be an improvement. My suggestion would be minor porting as stated above. Decarb of combustion chamber. Check cylinder for signs of wear while you are at it. Also great time to clean up valves and make sure you are seeing nice even wear on the seats. Set valves per manual. Mill the head to make true and flat again ( mill a little more if you feel its nessicary). New gasket and copper spray for best seal. Good clean carb, air filter, points, and condesor for good measure. Now , proper tuning is key. Make sure engine is reaching full RPM. Good fuel mixture on high end for sure. Possibly, slight advance of timing. DO NOT OVER DUE THIS. Good non ethonal fuel. Now you have a sweet running k301 which will out perform most due to just proper care and tuning. Won't get much more out of it without spending more money. At that point , switching to larger motor would make way more sense for blowing and daily use. These things are simple and all but most are recommended in manual. It may surprize you. But milling without picking up the slack every where else could result in less the satifactory performance. I am no engine builder but know a little to get in trouble.... Edited February 2, 2015 by Theroundhousernr 1 Share this post Link to post Share on other sites
oaktown1987 82 #9 Posted February 2, 2015 U need 93 or it will ping I know it won't hurt it Sent from my iPhone using Tapatalk I know engine builders go to Brian millers website Sent from my iPhone using Tapatalk Share this post Link to post Share on other sites
Theroundhousernr 589 #10 Posted February 2, 2015 (edited) U need 93 or it will ping I know it won't hurt it Sent from my iPhone using Tapatalk I know engine builders go to Brian millers website Sent from my iPhone using Tapatalk A stock kohler engine in no way has high enough compression to cause pre ignition of lower octane fuel to create any ping what so ever. Infact higher octane fuel will never mix and burn to potential in a stock kohler. It makes expensive exhaust basically. A ping from your kohler will most likely be from excess carbon build up in combustion chamber and or to far advanced timing. I am not sure of your comment made about "engine builders". But I can assure you Brian Miller makes no advice to run higher octane in stock Kohler motors and now go enjoy your new found horse power. I guess we will just have to agree to disagree. No need to take anything to heart. If anything sites like Bryan Miller show Mods that can be made to these motors and what needs to be made to produce power and require high octane fuel. Cam grinding, heavy duty con rods, major porting, and so on . Edited February 2, 2015 by Theroundhousernr Share this post Link to post Share on other sites
joel_400 59 #11 Posted February 2, 2015 As far as the head milling, I would only take off enough to true it up. Then use a thinner copper head gasket. Im pretty sure you can get a gasket thats .021 thick, which would net you the same as milling the head .040. As far as fuel, I do believe Kohler recommends 90 octane for use in a k series. Joel Share this post Link to post Share on other sites
Theroundhousernr 589 #12 Posted February 2, 2015 Only recommendation for 90 is if burning ethanol. Stuff is garbage all around. Would never use it unless I had to and yes I would buy 90 if I couldn't find non ethanol. Only reason I would buy it is because most 90 octane contains little to no alcohol. No other reason. Manual states if burning non ethanol, 87 is the number. If you burn 87 ethanol, you most likely not have any issues with detonation but it's bad for the aluminum in our carbs over time if left to rot. Share this post Link to post Share on other sites
WH nut 553 #13 Posted February 2, 2015 You wont gain enough oomph to make it worth your time 1 Share this post Link to post Share on other sites
bmsgaffer 2,043 #14 Posted February 2, 2015 Get a bigger engine and/or another horse with a bigger engine... Will likely be cheaper in the long run. Share this post Link to post Share on other sites
oaktown1987 82 #15 Posted February 3, 2015 Yes it did that's why they stopped making them Sent from my iPhone using Tapatalk Share this post Link to post Share on other sites
70sC120automadic 0 #16 Posted May 3, 2022 I have a 301 head milled 0.040 it ran really sweet started easy every time .you can have the head on with no gasket spin the motor and the valves don't hit .I had a crank issue but only due to the motor being excessively revved past reasonable rpm. Was the best running motor I say go for it Share this post Link to post Share on other sites
