26 thoughts on “6.5HP Briggs and Stratton RPM Setting

  1. I took my inductive tachometer and checked the rpm of my new Snapper Ninja with an 850 Nov, constant pressure engine and it said 3,450. I have never checked the rpm on my Honda hrr216 but they say 3,600. My 1150 Briggs engine on my 4.5kw briggs generator runs a solid 3,600 and produces 240 volts, 120 a side, under load. My Stihl saws run at 12 800 to 13,000. I use an Stihl edt9 for most tests and a Chinese digital tach for verification. The Stihl cost me $65 from my local Stihl dealer and the Chinese one $10 off eBay. They both generally read the same values when checking rpm, even though I like the Stihl one more and use it the most.

  2. Bruce can you please show how to fix a gas leak coming out of the primer bulb on this particular mower. A novice DYRer with average skills. thanks

  3. Bruce, spend $10 and get yourself a digital tachometer off of eBay. I got one and it works fine on 2 &4 cycle stuff. I use my Stihl EDT9 most of the time but I always double check its readings against my $10 Chinese tachometer, especially when I am setting WFO on one of my chainsaws. I limit, if possible, all of my Stihl saws to 12,600 to 12,800. They will comfortably exceed that figure but I like them to have a moderate four-cycle Richly tuned engines do not smoke down.

  4. Bruce, they do say to subtract 200 RPM from the maximum allowable RPM by blade length.

    For your observation, as the B&S service manual you have says, a 22" blade length is good for up to 3299 engine RPM, but with the 200 RPM subtraction that would be 3099 RPM = 3100 RPM.

  5. PA Lawn Guy. Bruce is 3600 okay for a two cycle. My Lawn Boy cuts much cleaner that way. I figure without valves to get in the way like overhead valve engines that should be okay. The reciprocating components are minimum weight and appear strong enough with closely balanced and tracking blade the compressive and centripetal load is minimized. Your thoughts please. (By The way, I value your opinions, you seem down to earth and have had a lot of experience to draw from.) I was thinking in this case maybe you have seen significant damage of a two cycle coming apart at elevated RPM's.

  6. I saw that manual on line and was thinking about ordering one. I was wondering what other manuals do you have and are there any you would recommend? Thank you sir.

  7. what your doing is extremely dangerous, opening side shoot of a mower while running, also no eye or ear protection and running a mower inside a closed garage.

  8. One last comment on rpm spec difficulty. Below is a link to B&S's published spec sheet. The "idle speed" for the 120000 series engines like the one in your video is listed as 1750! What's up with that!!?

  9. I have that very same mower which I recently bought second hand. It works fine on thin grass, but dies immediately when I try to mow thick grass. Do you think it could be that the blade isn't sharp enough, or the motor is too weak or some other reason? A new blade is worth the expense, but if it needs something major it's probably not worth the investment. Thank you for your thoughts!

  10. By the way, Bruce, your title is a bit off. That's a 6.75 engine, not 6.5. But I agree with your rpm setting at around 3100-3200. Its amazing how difficult it is to get the spec nailed down. Some say 3200, some as high as 3600. I called Briggs once & was told 2900 +/- 100. For me, 2900 sounds a bit anemic and 3600 sounds like the engine is racing. 3200 just seems to sound right and perform better.

  11. I'd highly recommend you get a tach that connects to the plug wire. It would save you time being able to adjust the RPM as the engine runs instead of adjusting then checking then adjusting etc. You could also use it on chainsaws, trimmers, etc. It would also be safer. I know you used caution by the spinning blade, but if you're like me kneeled down sometimes I put a hand down to stabilize myself. A hand inside the mower deck would be ugly fast.

  12. Great sourcing of the correct part for the bale my Northern Friend! Looks like you've got the same tach I have here. They're pretty reliable. I checked mine with a vintage mechanical tach I have here and it was very close on a number of engines. Big Thumbs Up Bruce! Sean~

  13. Wow over 3600 wasn't good. That's the same engine I mentioned that the valve seat wore too zero lash. I ground the valve stem to tappet clearance and two weeks later a no start. Haha now there was a 1/4 inch tappet clearance and the cam lobe wore down. It's scrap now. LOL

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