Predator 212 Governor Screw Adjustment

[SquidBonez]

If a Predator 212 does 3,600 RPM out of the box, how many RPMs can I get out of it if I completely back out the governor adjustment screw? I've heard some people say 3,900, and others say 4,300. I don't want to remove the governor without getting a billet flywheel, so this seems to be the next best thing to get an RPM boost (and for free).

 

[bob58o]

I cant call the throttle stop screw a governor adjustment screw.
The screw you speak of limits the throttle. If the max throttle position allows enough RPMs to throw the flyweights on the governor gear then the governor pushes the throttle back towards the closed position.

So I don’t see how that screw affects the governor at all. The governor setting can adjusted, but by changing the hole the spring is connected to.

IMO, the two are completely different things.

A governor works to limit RPMs. A throttle stop works to limit power.
So if you back out the throttle stop and gain RPMs, it is because the engine is making more power and you are still under the governor setting. IMO the governor will operate at same RPM no matter what you do to that screw.

 

[SquidBonez]

Really? Huh. I saw an old post where people were talking about a "governor screw". I wasn't sure if they meant throttle screw or not, but the way it was worded it sounded like the term was interchangeable...idk. They were saying that by backing out that screw the governor will still function but it will simply kick in at a higher RPM.

Link to post: http://www.diygokarts.com/vb/showthread.php?t=3316

 

[Jim289]

The screw in question should be called "Governor fine tuning screw". From what I have observed many (too many) mini bike and go kart people do not understand the mechanics involved with governor design. On stock throttle systems part of the throttle linkage is a spring. The governor internals up to the lever mounted on the engine needs to overcome spring tension in order to move the rest of the linkage that controls the throttle plate in the carb. If the spring tension changes from stock, the RPM's required to move the rest of the linkage will also change. That screw changes the spring tension. When the screw is backed out there is higher spring tension that the governor has to overcome. It takes more RPM's to overcome the extra tension. This is why higher RPM's are achieved at full throttle when the screw is backed out. The governor still functions, but it just has to work harder to overcome the extra spring tension.

 

[SquidBonez]

Oh, thank you for the clarification Jim. How many RPMs do you estimate I'll get with the screw completley backed out?

 

[Jim289]

That I do not know because I never had a tach hooked up when adjusting. Does seem to be a nice little bump up from 3600.

Best thing to do is to get a tach, pick an RPM target, then adjust to it.

---------- Post added at 12:30 PM ---------- Previous post was at 12:03 PM ----------

Another interesting thing is that the governor operates and can function at all rpm ranges depending on throttle position and load, including at startup.

One of the beautiful things about the stock governor setup is that this design helps make one handed, 1 or 2 pull starts possible. You do not need to manually move the throttle to start the engine. The throttle plate in the carb is already open with the engine off. As soon as the engine starts the governor moves the throttle plate to the idle position. This is because there is very little, if any spring tension to overcome.

 

[bob58o]

I guess that makes sense.
I admittedly throw away governors immediately and never spent too much time figuring them out.

If you can pull the lever more it will stretch the spring more... and require the governor to push harder to overcome the extra stretch.