engine speeds


LawnSite Member
i just got an hour meter/tachometer. My 12.5 hp toro 36 runs no load at about 3400-3500, with my double blades on each spindle, it runs about 3200 (i haven't cut grass with tha tach, this was on my drive way). i think i need to tighten my belts, but that shouldn't affect RPMs that much. what should i be running at no load and loaded? how do I adjust the governor? Shouldn't the engine run at 3600 RPM, if i hold the throttle open manually, it will run 3600, evnen with double blades, i don't want that reserve power to go unused<p>my 5.5 hp 21 inch JD walk behind runs no load at 2800, when i took the carb off to clean it this winter, i didn't put the choke linkage back on, any tips on how to put that on? oh and when i engage the blades, it just stalls, i have to let it warm up thoroughly, its like the governor isn't giving it any more gas. what RPM should this engine run at, isn't it different because of OSHA blade tip speed requirements?


LawnSite Silver Member
Central CT
What kind of engine? Briggs and Kohler are usually set 3600 fast idle no load, Kawi usually 3350. RPM shouldnt drop much if at all when blades are engaged if the governor is operating correctly and the equipment isnt underpowered.<p>Bill

Eric ELM

Husband, Father, Friend, Angel
Chicago, IL USA
It depends on which motor you have. Most engines have the RPM's in your manual. Dixie Chopper recommends 3850 rpm's no load on the Command and 3650 on the Magnum engine. I have a JD 21&quot;, but I don't have a tach on it. I know it seems to run slow, by just listening to it. Do you just need to know which hole the linkage goes in on the JD? I have to let the engine warm up on the JD before engaging the blade too. It is cold blooded, but I sure like the idea of being able to run the engine and not have the blade turning at all times. Let me know what you need to know on the choke linkage. Email me and I'll try to find the answer. :)<p>----------<br>&lt;a href=&quot;http://www.townserver.com/elm/&quot;&gt;Eric@ELM&lt;/a&gt;<br>


If you mean one of those inductive pickup maintenance meters when you say Hourmeter/tachometer I wouldn't put much faith in what they say. The ones I have tend to vary widely in their readings. I sue mone mostly for the hourmeter function, but there is no way I would rely on one to set engine speed.
Hello:<p>A general rule of thumb is most engines are suppose to run at 3,600 RPM's, load or no load. This is what I go by.<p>Always check your owners manual first don't let anybody, even me tell you something & think it's right!<p>If you are turning 3,600 RPM's then you put engine under load & it drops more than a 100 RPM's I would readjust the govenor. Make sure you know what you are doing.<p>I've read that for every % you raise your engine that it shortens you engine life by double that. Example if you raise your engine RPM's by 10% that it reduces the engine life by 20%. You will also loose 20% of reserve power!<p>If you raise the RPM's to much you will blow the engine.<p>If you have very much equipment I would recomend buying a tach. Please don't buy one of those El Cheap O's. You don't build a Million dollar home & put a used $25 door on the front. You don't buy a $25 tach to check a $1500 engine.<p>I had a battery-Solar operated one & it cost over $180. All you had to do is aim it at the plug wire. It tested 2 & 4 cycle, 1,2,4,6,8 cyl engines too! I think it's probably $500 or more. I know it saved me 1000's.<p>I might not be right on all of this, but it's what I go buy & if I'm not sure I read the owners manual!<p>Hey, that's all I know!<p>----------<br>GrassMaster - Home: www.lawnservicing.com<br>My Start Up Page www.lawnservicing.com/startup/


LawnSite Member
i took off my carberautor last night on my JD 21 inch and attached the choke. Now it starts up with the choke i disengage the choke, and it runs for a bit. Then it just stops. I think i`m gonna check the float bowl next time, maybe its clogged some how, if its empty right after it stalls out, then i have carb problems, otherwise, governor/linkage/throttle problems. so far as my big engine, for a while i had so that it fast idled at 3600-3750, and with the blade, 3500-3600, i then set the governor back to about where it is stock. i`m not worried about engine life, i put maybe 200 hours a year on my mower, i`ll be a new bigger engine or mower if it goes
Hello Paddy:<p>Try this if you want, forget about the choke & just put a small amount of gas in opening of carb. Crank it, if it runs for few seconds then quits, you have carb problems. This is way we check them at shop.<p>If a 2 cycle we spray a little WD40 in opening & if cranks runs few seconds then quits, well it's another carb job!<p>Removed & take apart carb, blow out with high pressure hose, check needle, float, gaskets & replace as needed. Then check gas cans, if any doubt get rid of gas!<p>I hope this helps!<p>----------<br>GrassMaster - Home: www.lawnservicing.com<br>My Start Up Page www.lawnservicing.com/startup/<br>

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