ENRICHER(AUTO CHOKE) By Alleyoop (Read 3,665 times)

[Alleyoop]

Yes similar but on cars with carbs it works the opposite their is a BUTTERLY that when cold it closes over the Intake to cut off the air so just less air is fed into the motor basically making them run richer. Then as the spring in the choke element heats up the butterfly opens up vertical just like the butterfly in your scooter Carb. The difference is the Scooter ENRICHER actually feds extra fuel in addition to the Pilot Jet feeding fuel. The Car Chokes do not feed extra fuel they just choke the carb air intake to cut off some of the being sucked in.
Alleyoop

As the choke heating element heats up the coil it rotates the Choke Plate into a vertical position the wider part of the Butterfly rotates down into the carb.

[FrankenMech]

Yeah, when the choke is closed it actually decreases the pressure in the venturi so the atmospheric pressure in the float bowls pushes more fuel through the jets. It can't close completely and differential air pressure 'pulls' it open. Carbs are always fun to play with. They are little mechanical marvels. The end result of a real choke or an enricher is a richer mixture entering the combustion chamber.

With this little scoot carb it is going to be interesting to see if I can just cover the air intake snorkle with my fingers to 'choke' it if necessary. I haven't studied out all the passageways and actions in that carb to see if the fuel bowl is vented externally so it sees atmospheric pressure from outside of the airstream. It may be vented by that drain tube. The pressure fluctuations may be enough to enrich the mixture anyway with the spring above the fuel needle.

Peering through passageways and tracking vents is just no fun anymore with my failing eyesight and no short term memory. I can't even carry on a verbal conversation. According to the doctors my brain was 88 years old in 2010, that makes it 92 now. It has not improved with the passing years. Dementia is very real.

That Holley carb does not have atmospheric bowl vents. The bowls vent to the intake airstream through those angle cut brass tubes into the air filter flange. Holley carbs were super tunable and adaptable to varying conditions.

[FrankenMech]

With outside temps running in the teens the engine was hard to start and it was balky even after warming up for a few minutes. The scoot was in an unheated garage so I don't know how cold it was. Putting my fingers over the snorkel holes did not seem to help starting. I may have to invest in a choke kit.

[tomcat]

With outside temps running in the teens the engine was hard to start and it was balky even after warming up for a few minutes. The scoot was in an unheated garage so I don't know how cold it was. Putting my fingers over the snorkel holes did not seem to help starting. I may have to invest in a choke kit.

Same deal here (cold temps, unheated garage) except mine won't start at all. Starter cranks, get not even a sputter. Verified kill switch is off & coil firmly attached to plug. Gas (with stabilizer) in tank. Last was able to start it a couple weeks ago when temps were a bit milder.
Guess I'll have to get some starting fluid & see if that works. If it wasn't a trike I could roll it into the heated breezeway overnight, would prolly start then.

[beebo]

If you are having problems with your enricher and you know it is good, you might look at your low speed jet and idle mixture settings. Cold start mixture equals idle mixture+low speed jetting+ enricher circuit. Initial cold start enricher mixture is fixed as far as I can tell, so if your idle mix or low speed jet is set too rich, you will have problems starting with the enricher added in.

I had this problem one time with my JCL 150. When I got it, it wouldn't start unless it was hot outside. I would have to choke it with my fingers and keep fiddling with it until the motor had really warmed up. Adjusting the idle screw out only helped a little. So I drilled out my low speed jet and everything changed. It would start on the first lick in even the coldest weather, but would start to load up and die as the bike warmed up. If the bike sat long enough for the enricher to cool off, it would flood out and not start at all. I could crank the throttle wide open and crank the starter until the mixture leaned out and it would start. I had drilled that jet a little too much. I wound up replacing it with a #42 jet and that fixed my problem. It starts good when cold or hot, has real good throttle response and acceleration, doesn't load up when it is hot. Idle mix is about 1 1/2 turns out.

[FrankenMech]

That tachometer I installed has one really nice side benefit. I can tell if I am getting a spark because it reads the cranking speed to be about 350RPM. I have no idea if that is right but at least I get some feedback without taking things apart.

If my trike sat just long enough for the enricher to cool off, it would flood out and not start at all. I couldn't even crank the throttle wide open and crank the starter until the mixture leaned out. I was just SOL until it sat for a few hours.

My idle mixture screw is a little rich. I need to work on it and make some adjustments. Without the enricher it may not run at all when cold. I dislike automatic functions that work 90% of the time. Murphy is always with me to make sure I am operating outside of that 90%. I prefer to eliminate as many automatic functions as I can and add manual controls. I just have a terrible time making changes or mods. I don't know how you guys with plastic panels do it. Even my ruckus style trike is a PITA to work on. I even made some modifications to make it easier but screws and my shakes just don't work well together.

[tomcat]

Well, the one thing I haven't tried is cranking with the throttle wide open.
Today it's snowing like hell here & I'll have to go out in awhile & get the snowblower going (which starts right up, as does my gas generator. Go figger).
So will try to start the trike again using the full-throttle method.
Looks like a manual choke is on my to-do list for next spring.

[FrankenMech]

Maybe I should just pull a carb off a Briggs & Straton and stick it on the scoot. LOL

I don't think I would get much in the way of throttle response.

Of course I could look around and see if anyone has a REAL carb. This semi variable venturi setup 'works' kinda like the old carbs on my '68 VW did. I threw that POS in the trash and dropped a Holley-Weber on right quick though. I wish I still had my bug. Hmmmm -I still have the rebuilt 1600cc engine with that carb on it....

[beebo]

Funny you should say that--I was just looking at a carb I pulled off my old 18hp briggs motor. It is a down draft carb, so fabricating an intake would take a bit of work. It might work on a 250, though.

You know, I did the same thing to my old VW--put the biggest jugs I could fit without boring the case, put dual port heads and a holley-weber off an old Pinto from the junkyard.It worked great! I loved those old carbs! They had a mechanical secondary that opened up at about 3/4 throttle, and really added some zip to a small motor. I thought about putting one on this old Porsche 914 I bought this summer, but a former owner had already removed the stock fuel injection and put a pair of dellortos on it! I think I'll leave well enough alone there ! But it does have one carb "barrel" per cylinder, much like my scoots, so have similar tuning issues. Maybe I'll fab some intakes and put 4 of these CV's on it...LOL

[FrankenMech]

I pulled my Holley-Weber off a 73(?) Vega sitting in the back 40. I fabricated my own manifold and right up to the point it cracked and failed it worked much much better than the store bought unit I replaced it with.

I have a 12HP single and 20HP two-cylinder Briggs sitting outside... The 12HP even runs. There is a brand new 420cc supposedly 16HP but probably about 12HP Honda clone sitting in the shop waiting for another project. That would make the scoot run fast.

Now if I can just get my hands to stop shaking long enough to use a wrench.