Manual chokes: why not?


Yes, fuel injection mechanisms have the ability to enrichen the mixture during cold start operation.

But they must return to the stoichiometric mixture within a certain amount of time, defined by emissions requirements.


Early EFI systems used an additional injector near the throttle to richen the mixture for cold starts. Needless to say it was called a COLD START INJECTOR. Early BMWs had a timer that was discontinued. Installing a momentary on switch under the dash that operated the 5th injector via a relay made the cars driveable for determined owners. Others traded up.

And while the dash mounted control was called the CHOKE, SU and Stromberg equipped cars actually controlled the bowl/float to richen the mixture.


I dunno. I’ll remain skeptical of self-driving cars littering the road as I recall flying car predictions of the 50’s. Just because they can doesn’t mean they should or will.


Mikuni carbs used in motorcycles also had no choke, but had an enrichening circuit that was controlled by a cable. It was a miniature second venturi with its own jets, the “choke” opened this venturi and allowed it to provide its rich mixture along with extra air for a fast idle.

The Amal carb on my old BSA 250 had a button that you pushed down. It would push the float down and allow you to overfill the float bowl for a rich starting mixture. This was called a “tickler”.

The Kiehin carbs used on Hondas had true chokes, however, they often were guillotine slides instead of butterfly valves.


I’m pretty sure I read it online a few years ago on an automotive humor site.


I just did some checking and found–somewhat to my surprise–that Popular Science ran the Model Garage monthly feature from the late '20s up to around 1970.
So, somebody on that automotive humor site undoubtedly cribbed the tale from that monthly feature, at some point.


My '75 Civic with the CVCC engine had a manual choke.
So it was possible to meet some emission standards with one.
It also had contact points.


I believe the idea isn’t so much that a vehicle with a manual choke couldn’t pass the emissions tests of the day

It’s more that a manual choke will be misused, and thus a vehicle with a manual choke will spew out more pollution, versus the identical car with an automatic choke


I remember" Gus "fondly, also The “Earthworm” heavy equipment traveling salesman from the Sat. Evening Post named Mr Potts? Botts?

There is also at least on brand of motorcycle on the market now that has a control marked" Choke " that is really a fuel injector enrichment control and if you don’t use it on a warm bike it makes it hard to start. If it was really a choke it would flood a warm engine.


I had spent a week hiking in the Grand Canyon 40 years ago. When I got back to the car a bunch of people were having a hard time starting their cars; some had run their batteries down. A service guy drove out and told us the problem was the thin air at 8,000 feet. He opened the hood, took the cover off the air cleaner, stuck a screwdriver down the throat of the choke, started the cars up. That’d be another use for a manual choke. There’s a high-altitude compensator package for my pickup (which I lack).


Holding the accelerator to the floor opens the automatic choke, a clear-flood mode over ride.


Modern technology makes altitude compensations


Do not get it, choke control for lawnmower, no idle speed control, Now I do not need that bad boy running at whatever rpm, could do with less and still cut the grass, fuel efficiency they say, bogus I say.


My father was so cheap that he would run his mower at slow speeds to use less gas back in the day when mowers had engine speed control. Keep in mind this was back when gas was less than a dollar a gallon. I always cranked the mower up as fast as it would go.


I don’t own a lawnmower (too much area for me to cut on my own…) but I do have a snowblower of very recent vintage, and it has both a choke and an idle speed control.

When I started it for the one and only time…so far…this winter, I put it on full choke because the ambient temperature was below 20 degrees. It put out so much black smoke that I immediately began to “back-off” on the choke and I found that, even at relatively low temperatures, I was able to open the choke fully after only 30 seconds or so.

However, when I had to attack the very high “wall” that the city snowplows had built-up at the bottom of my driveway, I found that I had to keep the idle speed at…almost full…in order to keep the engine from stalling.


My garage stays above 40-50 degrees so when I start the blower, I only give it about half choke and that does it. I have both the choke and the throttle. On the new carbs though, there is no mixture adjustment, just the jet. All you could do is change jets or drill it out. New carbs are only about $25 now though so I have one sitting on the shelf.


What EPA rules are applied to any lawn mower or snow blower? There aren’t any that I know of.

Personally (EPA or not), I prefer an automatic choke. It’s a proven reliable technology. Why go back?


There probably aren’t any EPA regs, but savvy manufacturers do make sure that their small engines comply with California’s CARB regulations.

I’m sure that nobody sells many snowblowers in Cali, but most of the newer ones are certified to comply with those CARB regs. Why miss-out on sales in the world’s 9th largest economy?

And, if snowblowers are now certified for compliance with CARB regulations, I’m sure that lawnmower engines are similarly in compliance.


I see ads for power equipment that specifies CARB and non CARB compliant but since there are no CARB compliant models on display locally I don’t have a clue whether they use manual chokes.However I am all too aware of the problems with current impulse type carburetors. My 20 year old Stihl chainsaw ran trouble free until I put ethanol fuel in it but newer model weed eaters, blowers, etc with the primer button won’t see a third season without carburetor repair or replacement. Could there be a conspiracy to frustrate the public into buying battery operated lawn equipment?


My CARB-compliant snowblower (a Toro) does have a manual choke.

Because of problems that neighbors have had with their power equipment that resulted from ethanol-laced gas, I have opted to use only ethanol-free gas in my snowblower.
Since there are no stations in my neck of the woods that sell the stuff, I have to buy it in 1 qt cans, from Lowe’s. Based on the price per can, this stuff costs approximately $24 per gallon!
Yes, it does contain a stabilizer, so that it can be stored long-term (as well as detergents and “friction modifiers”), but this product must have a really big profit margin.