1st go-kart project advice

[Denny]

The problem is once the engine is “ run awhile” the piston, cylinder and rings are no longer round due to normal wear. See where I’m going. Unless those rings go back on the piston in the exact same orientation (down to the micron) you run the risk of creating a mosquito fogger. May not happen today or tomorrow but it will happen.

 

[madprofessor]

Now that really does makes sense to me. Smoke rising usually does mean performance falling, so I can see where there's a decision to be made as to the tradeoff.
For the power purists, there's a saying in my industry about motors..............
Motors come with factory-installed smoke. If the smoke gets out, the motor's bad.

 

[ThunderKart79]

The rings and valves both can take your performance away. I always lap valves and install new rings not saying that is necessary but when I tear into an engine if I don’t gain performance then I considered it a failure so in short it will run good with the old rings but if you install new ones you can condition your engine while breaking it in to run in a go cart instead of a lawnmower or whatever it was in

 

[madprofessor]

Great attitude, want to see some real results for my work too. Besides, there's the cost to you of gaskets at the very least when tearing down. Yes, a new sidecover gasket every time. No, I won't ooze out some gasket maker to seal up a case, there's shaft endplay to consider.

 

[Bansil]

Mmmm...engineer

Have you checked your MCM "manual" yet?

I keed, I keed.....I work with Engineers all the time and had to joke....seems they all where given a catalog at graduation

Cool project

 

[nstiesi]

Still in the middle of the rebuild. I have the core of the motor re-assembled, working on the carb now.

I do have a question about the governor, and I know people here probably dont have experience with this EXACT motor. I want to leave it in place for safety, but so far I don't see how it would be effective. It is a mechanical governor built into the oil slinger, and driven by the camshaft gear. As the cam shaft speeds up, centrifugal force opens the bracket arms pushing on a crank lever that pulls the butterfly valve on the carb closed, opposing a small spring also attached to the throttle linkage.

What I am not understanding is, if my throttle pedal is linked to the butterfly, I will EASILY be able to defeat the governor with my foot, right? If so, what is the point of having the governor on, and if it is gone, how do I keep my RPMs in the safe zone? Limit my throttle pedal travel by some other means (put my own adjustable hard stop on the linkage)?

Thanks!

 

[madprofessor]

The governors I'm familiar with aren't rigid-linked, there's opposing springs at work that aren't overcome by pedal push.
Limiting gas pedal travel is something to do as a safety measure for kids, limiting both top speed and acceleration together.
Nobody I can think of wants to limit the acceleration of their karts, floorboard limiting only. The governors I've seen don't do anything but limit rpm's at the top end, and are completely unaffected by pedal travel. They pull on a spring that can overcome the springs in play for the throttle.

 

[nstiesi]

You know what, I think I get it. I wasnt thinking about the mechanics involved properly at first, namely, that my throttle pedal will have its own, much larger spring. Without the governor engaged, the small governor spring although relatively tiny, is more than strong enough to move the butterfly. So if my throttle linkage is pulling on that small spring, it acts as a solid link (compared the butterfly itself), UNTIL the governor pulls on it.

Essentially, I am only moving the connection point of the gov. spring with my pedal, NOT stretching the gov. spring with my pedal. Regardless of where the throttle connection point of the gov. spring is, once the governor crank lever starts pulling on it, it will stretch and close the butterfly.

 

[nstiesi]

She lives! All reassembled and after alot of priming and carb cleaner in the intake, it fired. I didn't notice any smoke, but I wasn't able to run it very long.

The motor was surging pretty bad. I suspect the governor spring is a bit wore out. If I held the throttle plate at a fixed position it evened out.

I did the static governor adjustment, but not the top no-load. I need to get my hands on a tach, and I want to make an adjustable linkage for the governor screw. The Briggs manual requires bending the tab where the spring attaches, but I'd like some more control over it.