Venturabass
Bronze Member
Hi, I recently purchased a John Deere X540 about a year ago. It's in fantastic shape but I always thought the full throttle engine speed "sounded" a little on the slow side. I'm also finding my recent snowblower addition (48" Bercomac Northeast) only blows about 35', and believe this is a little less distance than is typical with these units. So I put the 2 issues together and decided to install a Tiny Tach digital tachometer. Low and behold maximum engine rpms with the throttle lever all the way is only 3,180 rpm.
I have the John Deere service manual, and the Kawasaki service manual, both describe the same adjustment procedure to increase (or decrease) engine rpm. First I checked that the throttle cable itself was adjusted correctly, which it was. Next the manual describes a control plate that attaches to the engine, where the throttle/choke cables are routed through, and adjust each function through this plate using various linkages for each. See the image below. I marked the bolts. When I bottomed the plate out all the way and I can only however obtain a maximum of 3350-3400 rpms.
Looking further at the setup, it looks like the throttle cable connects to the pivot arm on the control plate, and from here a spring connects this to the lower end of the governor arm. After this there is a second spring/rod that connects the upper end of the governor directly to the throttle on the carb. See the 2nd photo below. It seems like when the throttle lever on the dash is moved to increase engine speed, the pivot arm on the control plate asserts spring pressure on the lower end of the governor arm. Oddly though it doesn't appear that the governor arm moves at all, it stays in the horizontal position, but somehow the throttle on the carb opens. The governor arm only seems to move when you jerk the throttle in one direction and the governor quickly compensates and then returns to position.
So the question is, how to I increase the engine speed further? My goal is 3600 rpm so I can maximize my snowblower throwing distance? If I manually apply more tension on the spring connecting the control plate and lower governor end, it does increase the engine speed. I also noticed the top end of this spring appears bent, but I don't know if this is how it comes from the factory or not? Also the lower end of the governor has a second lower hole. If I install the spring through that second hole it increases the distance between the 2 pivot points, so tension on the governor would also increase. My gut tells me my next step is to apply more spring tension to this governor in one of these 2 ways. However, I'm not too familiar with how the governor works and though I've worked on a lot of other aspects of cars and tractors, have never had to adjust engine speed before. I'm looking to see if someone has had this problem where they run out of adjustment, or if they can verify the next step.
I have the John Deere service manual, and the Kawasaki service manual, both describe the same adjustment procedure to increase (or decrease) engine rpm. First I checked that the throttle cable itself was adjusted correctly, which it was. Next the manual describes a control plate that attaches to the engine, where the throttle/choke cables are routed through, and adjust each function through this plate using various linkages for each. See the image below. I marked the bolts. When I bottomed the plate out all the way and I can only however obtain a maximum of 3350-3400 rpms.
Looking further at the setup, it looks like the throttle cable connects to the pivot arm on the control plate, and from here a spring connects this to the lower end of the governor arm. After this there is a second spring/rod that connects the upper end of the governor directly to the throttle on the carb. See the 2nd photo below. It seems like when the throttle lever on the dash is moved to increase engine speed, the pivot arm on the control plate asserts spring pressure on the lower end of the governor arm. Oddly though it doesn't appear that the governor arm moves at all, it stays in the horizontal position, but somehow the throttle on the carb opens. The governor arm only seems to move when you jerk the throttle in one direction and the governor quickly compensates and then returns to position.
So the question is, how to I increase the engine speed further? My goal is 3600 rpm so I can maximize my snowblower throwing distance? If I manually apply more tension on the spring connecting the control plate and lower governor end, it does increase the engine speed. I also noticed the top end of this spring appears bent, but I don't know if this is how it comes from the factory or not? Also the lower end of the governor has a second lower hole. If I install the spring through that second hole it increases the distance between the 2 pivot points, so tension on the governor would also increase. My gut tells me my next step is to apply more spring tension to this governor in one of these 2 ways. However, I'm not too familiar with how the governor works and though I've worked on a lot of other aspects of cars and tractors, have never had to adjust engine speed before. I'm looking to see if someone has had this problem where they run out of adjustment, or if they can verify the next step.
Last edited:
