horseman with no horse 55 #1 Posted August 4 (edited) i got my B48M running but it seems to run wayyyy too high in RPM. we stuck a P216 carb and manifold on it so i dont know if thats the cause. i also have no idea how to adjust the governor lol. any tips or idea? heres a video of it running. id love to find another B48M or even a B48G 19.9 variant, if anyone has got one they wanna sell let me know please. Edited August 4 by horseman with no horse Share this post Link to post Share on other sites
horseman with no horse 55 #2 Posted August 4 https://www.youtube.com/shorts/081WAt3f0zA Share this post Link to post Share on other sites
lynnmor 8,076 #3 Posted August 4 The Onan Service Manual for your engine is available here. Look where the high speed stop is located and bend till you get the correct maximum speed. And leave your hands off the governor linkage to the carburetor. Adjust the following: The idle mixture screw. The lowest speed screw. The governed idle speed screw. The maximum speed stop. Share this post Link to post Share on other sites
horseman with no horse 55 #4 Posted August 4 thank you, i will definitely look into it later today. Share this post Link to post Share on other sites
horseman with no horse 55 #5 Posted August 4 also i had my hand on that linkage to prevent runaway, you can see me give a sideways thumbs up when my buddy wanted to grab the actual tab the throttle cable hooks too, as soon as he did i had to grab the arm to keep it from running away in RPM. Share this post Link to post Share on other sites
lynnmor 8,076 #6 Posted August 4 Later model Onans had a plastic flyball spacer that can crack and allow a runaway speed. Yours should have all metal unless it was replaced, the metal ones were problem free but it is possible that it didn't have enough press fit. I doubt that is your problem but that is a possibility. Do those steps I mentioned earlier in the order that I posted, I can guide you thru the process after you take a good look at it. Look at the timing cover for evidence of previous work. 1 Share this post Link to post Share on other sites
horseman with no horse 55 #7 Posted August 4 thank you very much, will do Share this post Link to post Share on other sites
RED-Z06 2,679 #8 Posted August 5 Is it trying to take off with no spring input? Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,733 #9 Posted August 5 Seems to me the distance between the carb and the governor could have changed so that adjustment would be required or at least checked. Section 7 Fuel 1 Share this post Link to post Share on other sites
horseman with no horse 55 #10 Posted August 29 (edited) On 8/5/2025 at 9:39 AM, gwest_ca said: Seems to me the distance between the carb and the governor could have changed so that adjustment would be required or at least checked. ahhhhh i thought about that. interesting thats a great point Edited August 29 by horseman with no horse Share this post Link to post Share on other sites
