Speed governors (defeating)

I've seen a few posts about speed governors recently, so I thought I'd share this info.

There are four main ways in which speed governors work on simple engines:

1) Restrictor in the exhaust. Either a 'washer' in the exhaust port, or by design of the muffler/pipe itself. This is (in most cases) easy to defeat. Either remove the washer, or replace/modify the limited exhaust pipe/muffler.

2) Restriction of carb opening. This is done with a screw or other stop in the carb body, and sometimes with the throttle control / twistgrip itself. Again, relatively easy to defeat.. remove whatever is preventing full opening of the throttle.

3) Active flyweight or vane governor. You see this most often on lawnmower/snowblower motors. As RPM increases, a vane (driven by air from the flywheel) or a set of flyweights (driven by RPM of the governor) push-back against the throttle. A tip-off to this style of governor, is that the throttle doesn't directly open the carb - it acts on a spring which tends to open the carb, but can be overridden by the force of the governor.

4) Late timing. Sometimes engines are detuned by simply retarding the spark timing. Find a suitable earlier timing, and run with it.

Hope some of you found this helpful. Please feel free to correct/modify/add info as needed.


Re: Speed governors (defeating)

Xyplestop Florbledo /

Saved! and thank you.

Re: Speed governors (defeating)

One addition:

There's another method for 'governing' engines as well, but this falls more under the heading of 'detuning' - I'll include it for completeness.

5) Over-rich (conservative) carb jetting. Engines are set up a little too rich, right from the factory. This works to limit output power, but also provides a safety margin for the manufacturer. The richness causes the engine to run cooler, which makes the possibility of a piston/cylinder failure much less likely. You get less power, and the manufacturer gets less warranty returns.

Re: Speed governors (defeating)

Xyplestop Florbledo /

That one I think Id leave alone, Piston failure I'd raher avoid

Re: Speed governors (defeating)

The four ways you've listed are rarely the case in mopeds. The restrictions are usually in

1. carb body bore(lke the 14/12 Dellorto)

2. Intake, (like the Bianchi Snarks 7mm manifold)

3. porting(sachs "A" cylinders) or

4. exhaust headers restiction(some sachs especially)

The only "washer" i've removed from a moped was the intake restrictor on my Derbi, and that was only there to match the 12mm DEllorto to the 15mm manifold.

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