The kids have a go-kart with a 5hp Subaru engine. Yesterday we got rid of the wore out centrifugal clutch and installed a torque converter. It starts on the first pull and idles really well, but when ran at wide open throttle it surges pretty bad, and doesn't reach enough rpms for the pulleys to go all the way to full speed mode. I tried it both while driving and up on blocks. I verified the pedal does fully pull the linkage to it's full travel. When I had it on blocks I manually opened the throttle (bypassing the governor) it ran up enough speed to fully engage the pulleys and it sounded pretty good. I'm not sure if I'm looking at a carb problem or a governor problem. I didn't see any other linkage holes that would let me adjust how the governor attaches to the carb. What do you guys think?
Certainly sounds more like a carb problem if it'll rev fully with little or no load. Floor it until symptoms present and shut it off asap, look at the spark plug. I bet it shows lean. Anything lighter than "milk chocolate brown" and you're short on fuel.
Most small engines use a mechanical governor, so unlikely it's causing trouble, but I'm often wrong about stuff.
When our 9hp Honda powered karts do the surge thing, it's either debris in the carb, dirty fuel filter or a worn out governor wheel. Since it seemed to work when you bypassed the governor, try putting another spring between the throttle and governor arm. I'm not very familiar with the Subaru small engine but I imagine the governor works the same as other small engines and an additional spring on the governor will likely correct the surge.
Robin engines are also very picky about oil levels if it's an oil-slung governor. If it's the slightest bit low, there isn't as much oil pushing on the governor. Also check the oil after running it and see if it's foamy or has bubbles.
Newer small engines are also calibrated so lean to combat new EPA regs, so running lean is a big possibility.
Also, I don't see anything wrong with bypassing the governor other than taking away over-rev safety.
In reply to Curtis73 (Forum Supporter) :
Bypassing the governor was the first thing we did when we hotrodded lawnmowers as kids.
Curtis73 (Forum Supporter) said:
Robin engines are also very picky about oil levels if it's an oil-slung governor. If it's the slightest bit low, there isn't as much oil pushing on the governor. Also check the oil after running it and see if it's foamy or has bubbles.
Also, I don't see anything wrong with bypassing the governor other than taking away over-rev safety.
We actually changed the oil yesterday, so that's full.
As far as bypassing the governor, I'm pretty sure my kids would ventilate the block on the first day.
In reply to gearheadmb :
Cannot speak for the Robin, but a Tecumseh will run into valve float before the rod lets loose, and since it is a side valve, who cares if the valves float?
