Briggs 12.5 HP RPM levels

[jakesmurray]

I have a Briggs 12.5HP I/C Quiet engine that needs the rpms adjusted. While at run, it is not as high as it should be. First of all, how do I go about doing this? Do I adjust the carb, governor, or both? Also, what should the run and idle rpms be? Thanks!

 

[Arwing64]

A Briggs and Stratton engine generally runs at 3600 rpms for the most efficiency and power output. The throttle cable that hooks to the engine bracket may not be adjusted correctly. There should be a small bolt and a plate that holds the cable in place. Push the throttle lever all the way up, and then connect the linkage, making sure that the position on the engine is also running full throttle. Once you think you have it in the right spot, tighten the screw and test to make sure that the throttle cable linkage is holding. Then test run your engine. If it runs noticeably fast, you may have to move the throttle cable back a little. If it runs too slow, push the throttle cable up a little. This is mainly trial and error. If this still doesn't fix the problem, it may be a governor linkage problem. Be sure that all the linkages are hooked up correctly, and be sure that the governor arm or governor linkage is not bent or broken. A tiny spring should also be hooked up.

Let me know if you have any further questions. I would be happy to answer them for you.

 

[bertsmobile1]

To give you accurate information we need the engine numbers, Model, Type & Code.
You will find them stamped into a plate rivited to the blower housing , stamped into the blower housing or on the rocker cover.

Depending upon the exact model it should idle somewhere between 1200 & 1500 rpm and do 3,400 to 3,600 rpm, no load with the throttle lever fully open.
You need a tacho to set it properly and always err on the slow side.
Too slow = a little less power
Too fast = bang then no power

 

[jakesmurray]

Better late than never, right guys? :laughing:

I did eventually get this engine tuned real nicely. It ran very well. I sold the machine it was on three years ago when I got my Craftsman. It was a Murray 40" cut rider.