Is it a good idea to start a engine at WOT? WHAT????

Hi ,

I just bought a TroyBuilt 54" Mustang with the B&S 25 HP engine.

I find it odd that the choke is at wide open throttle setting. (Seams a lot of engines are that way these days I guess)

Why would engine designers want to start a engine at wide open throttle?
It is hard for me to do it, so I start the engine and as soon as it starts I lower the throttle to a high idle.
But now I am thinking maybe I should look into this a little more as surly the people that design and build engines
are a lot smarter than I.

It is just hard for me to think about an engine running fast when the oil has drained off its components.

So the question is Should I worry about the engine at start up?
What do other owners do when starting?

Thanks.

It is a governed engine, not a throttle control like your car.
So yes you start it at WFO and you leave it there.

Engines that do not have a separate choke control actuate the choke at full throttle by the throttle control. This is a cost saving thing for the engine/machine manufacturers and supposedly simplifies engine starting.
You will need to go to full throttle to cold start the engine and pull the throttle lever back to low idle and let the engine warm up before operating the machine. I personally prefer a separate choke control as during engine warmup sometimes a little choke is needed to keep the engine running as it warms up particularly during cold weather operation. Many machines are hydraulically driven and the hydraulic oil will be cold and slow moving until it also warms up.
There are many engines that are set to start and run at high RPMs such as generators and small push mowers, so this is not uncommon.
The throttle position sets the governor speed, the governor controls the throttle plate position in the carb.

On single-speed engines, you don't have much choice in the matter. I don't like it, either.

I’ve never like the single cable systems either. If you have been around motors for decades then it’s hard to absorb that fast rpms at startups don’t put wear on the motor. I always let the motor spin a bit then engage the lever to choke until startup then drop to idle till it warms a bit. Doing it this way let’s me feel like oil is getting around before the motor starts.

It is not vertical cylinder car engine that does 15000rpm then goes bang if held WFO at start up.
Half the car engines now days rev at 2000 rpm when idle.

A lot of the lube is done by splash and the faster those paddles spin the further up the bore they throw the oil
The bore is horizontal so should always have some oil sitting in it and most are 1 or 2 cylinder engines so there is not a lot of temperature equalization to be done at start up.
also the cooling system is the air blown across the engine and this is not linear so a slow warm up allows the head to get substantilly hotter that it should .

You are over thinking things .
Those with air cooled motorcycles will be used to having to either rev the engine much higher than idle for quite a while till the engine warms up, ring pressure builds , carb warms up and the bike will remain idling when you take your hand off the throttle .
While you are not holding the throttle wide open on a motorcycle you will be holding it around full cam & timing advance so with most of my vintage engines, that is way higher than the actual running speed around peak torque revs.

Also remember the ENGINE IS NOT WFO>
If you get off the mower when you start it and have a look the throttle is WFO till the engine fires then the governor takes over and closes the throttle butterfly holding it around 1/3 .
Once again you are confusing the throttle actions of manually controlled engine like your car or motorcycle and a GOVERNED engine.

Also if you actually read the mower manuals, the running speeds of 3000-4000rpm are usually called HIGH IDLE and are nothing like WFO
Hold the governor wide open if you really want to see what WFO really is but don't do it for long because the engine will happily race to well over 5000rpm just before throwing the piston or rod.

The throttle setting IS NOT THE SPEED THAT THE ENGINE WILL RUN AT
It is the widest throttle position that the governor can allow the engine to use, not the throttle position that the engine has to run at .

SO AT START UP THE ENGIN NEVER EVER RUNS WFO, not for a milli second
And yes I am shouting because very few seem to understand the theory of governors.
So get off you bums and watch the throttle plate at start up

Mad Mackie said:

Engines that do not have a separate choke control actuate the choke at full throttle by the throttle control. This is a cost saving thing for the engine/machine manufacturers and supposedly simplifies engine starting.
You will need to go to full throttle to cold start the engine and pull the throttle lever back to low idle and let the engine warm up before operating the machine. I personally prefer a separate choke control as during engine warmup sometimes a little choke is needed to keep the engine running as it warms up particularly during cold weather operation. Many machines are hydraulically driven and the hydraulic oil will be cold and slow moving until it also warms up.
There are many engines that are set to start and run at high RPMs such as generators and small push mowers, so this is not uncommon.
The throttle position sets the governor speed, the governor controls the throttle plate position in the carb.

Click to expand...

Ditto......