Emulsion Tube?

[courts94s]

I bought an air intake for my 212cc Predator. Once I drill the main jet, it will essentially have the "Stage 1" performance kit, minus the emulsion tube. Has anyone/does anyone, have the header + air intake + larger jet, without an upgraded emulsion tube? I upgraded the parts for size and fit, not for performance. I'm just curious if anyone has a running predator with this setup? ...or do I need to spend $7 to ship a tube?

---------- Post added at 07:54 PM ---------- Previous post was at 07:52 PM ----------

I forgot to say that I googled what an Emulsion tube does, and searched the forum for peoples comments and input on the emulsion tube. But only found one person who said the didn't think upgrading it was needed. They didn't say wether they have done it or not, and what their setup is.

 

[mckutzy]

A gx160 typically is one that is used... (As I recall) it helps to mix the fuel with air, by atomization...
It does help, there is a bit of pick me up when pared with a drilled jet.

It doesn't wear out, so getting a used one is an option. I'd go to a lawnmower or rental shop.. They'll have junk bit full of carb bits, and I'm sure wont be more than $1 at most if you ask nicely... Might aswell get a few jets aswell.. While your at it...

 

[courts94s]

A gx140 typically is one that is used... (As I recall) it helps to mix the fuel with air, by atomization...
It does help, there is a bit of pick me up when pared with a drilled jet.

It doesn't wear out, so getting a used one is an option. I'd go to a lawnmower or rental shop.. They'll have junk bit full of carb bits, and I'm sure wont be more than $1 at most if you ask nicely... Might aswell get a few jets aswell.. While your at it...

Yep, good call on the lawnmower shop. I always forget about this one in town. I'll try there, before I pay that much for shipping.


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[Flyinhillbilly]

The emulsion tube just introduces air into the fuel that gets pulled through the main jet. That air is metered by your air bleeds in the throat of the carb. The little holes in the bottom of the emulsion tube are where your pilot jet gets it's fuel. It all has more to do with the fuel curve at part throttle and doesn't matter as much at wot. It will work without the smaller emulsion tube, but it may not be as crisp in place that it would be otherwise. My neighbor put a 160 e tube in his sons predator and it sharpened up the throttle response. Worth $7 IMHO.

 

[mckutzy]

I got a few for a $1. Buddy let me pick in the bin for what I wanted... Usually pretty good people.

 

[courts94s]

The emulsion tube just introduces air into the fuel that gets pulled through the main jet. That air is metered by your air bleeds in the throat of the carb. The little holes in the bottom of the emulsion tube are where your pilot jet gets it's fuel. It all has more to do with the fuel curve at part throttle and doesn't matter as much at wot. It will work without the smaller emulsion tube, but it may not be as crisp in place that it would be otherwise. My neighbor put a 160 e tube in his sons predator and it sharpened up the throttle response. Worth $7 IMHO.

There's a reputable lawnmower repair place here. The cost of parts are retail, but still cheaper than "on sale" plus shipping. I'm just gonna get one from them. Even if they don't have stuff in stock, the don't charge extra to order stuff to their shop.


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[Flyinhillbilly]

You're lucky. My local lawnmower shop won't work on or order parts for Hondas. Maybe I should go into the small engine business.

 

[courts94s]

You're lucky. My local lawnmower shop won't work on or order parts for Hondas. Maybe I should go into the small engine business.

My father-in-law owns a small engine repair and lawn equipment sales shop, so I get dealer pricing when I'm home on leave. Rotary name brand (not the cheap Chinese ones) clutches are only about $30, rather than $60 retail. 15x6x6 turf saver tires are only about $15. Pretty much any part you can order at OMB warehouse, can be ordered to their shop at the price they pay for it, before they charge resale prices to customers. It's a great deal.... but it will be another 6 months before I go home. And getting them to mail a giant box of parts with take an act of congress!


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[FreeRunner15]

I googled what an Emulsion tube does, and searched the forum for peoples comments and input on the emulsion tube. But only found one person who said the didn't think upgrading it was needed. They didn't say wether they have done it or not, and what their setup is.

I have never found en e-tube necessary. Even with a gx390 carb and 290 cam. The main jet controls enough for this motor displacement size unless you only plan on high rpms (7.5k+) because the engine will want to stall at low speeds. I HAVE DONE THIS BEFORE. several times.

The effect of too big of a main jet will be needing to have the butterfly open for the engine to even start.and to stay running (vroom.....vroom....vroom....vroom is what you'll sound like trying to keep the engine alive with throttle manipulation) at low speeds. But when the kart gets going..it gets going. lol

 

[bob58o]

If your engine won't run with the throttle closed, I'd look at the Idle Jet before the main jet.
Butterfly closed = idle circuit = idle jet
Butterfly open = main circuit = main jet

 

[courts94s]

If your engine won't run with the throttle closed, I'd look at the Idle Jet before the main jet.
Butterfly closed = idle circuit = idle jet
Butterfly open = main circuit = main jet

That's like Chinese to me. I'm going to have to google this.


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[bob58o]

gx style lawnmower carbs are simple.

Only two circuits where you can tune.
When the butterfly valve is closed the carb is running off the idle circuit.
The air/fuel ratio is determined by idle jet. If too rich at idle (too much fuel for the amount of air) then the idle jet is too big.

When at WOT, the carb is running off the main or primary circuit. The air/fuel ratio is determined by the main jet. If too rich when at WOT, then the main jet is too big.

---------- Post added at 01:13 AM ---------- Previous post was at 01:12 AM ----------

Here's some explaining on a more complex carb.
http://www.dansmc.com/carbs2.htm
The idle jet system (comprised of pilot air jet, pilot fuel jet and pilot fuel screw) controls from 0% to about 25% of the throttle opening. The throttle valve controls 0% to 35% of the throttle opening. The needle jet and jet needle control from 15% to 80% of the throttle opening and the main jet controls 60% to 100%. This means that when you open the throttle about one eighth of the way open, all of the gas/air mixture going into your engine is controlled by the idle jet. As you can see, the different jets over lap the operating range of each other. That is, the jet needle starts to effect things before the effect of the idle jet ends. This is something to remember when working on carbs... everything is interconnected. Change one thing and it will effect other things.

 

[courts94s]

gx style lawnmower carbs are simple.



Only two circuits where you can tune.

When the butterfly valve is closed the carb is running off the idle circuit.

The air/fuel ratio is determined by idle jet. If too rich at idle (too much fuel for the amount of air) then the idle jet is too big.



When at WOT, the carb is running off the main or primary circuit. The air/fuel ratio is determined by the main jet. If too rich when at WOT, then the main jet is too big.



---------- Post added at 01:13 AM ---------- Previous post was at 01:12 AM ----------



Here's some explaining on a more complex carb.

http://www.dansmc.com/carbs2.htm

The idle jet system (comprised of pilot air jet, pilot fuel jet and pilot fuel screw) controls from 0% to about 25% of the throttle opening. The throttle valve controls 0% to 35% of the throttle opening. The needle jet and jet needle control from 15% to 80% of the throttle opening and the main jet controls 60% to 100%. This means that when you open the throttle about one eighth of the way open, all of the gas/air mixture going into your engine is controlled by the idle jet. As you can see, the different jets over lap the operating range of each other. That is, the jet needle starts to effect things before the effect of the idle jet ends. This is something to remember when working on carbs... everything is interconnected. Change one thing and it will effect other things.

I don't have any of the Carb components yet. So I'll try it with the new Air filter and see how it does, then do the jets this weekend.
I've change the header pipe between a couple different stock engines, and didn't notice a difference (aside from sound). I'll see how it does with the header and air intake, while I try to find a small drill bit for the main jet. I just got the live axle components in today, so I have a little while before I need the engine running.


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[FreeRunner15]

If your engine won't run with the throttle closed, I'd look at the Idle Jet before the main jet.
Butterfly closed = idle circuit = idle jet
Butterfly open = main circuit = main jet

Very Valuable Information: Noted.

 

[bob58o]

The effect of too big of a main jet will be needing to have the butterfly open for the engine to even start.and to stay running (vroom.....vroom....vroom....vroom is what you'll sound like trying to keep the engine alive with throttle manipulation) at low speeds. But when the kart gets going..it gets going. lol

Was this with the 307 cam. That cam needs a 5k idle / clutch stall speed.

 

[Flyinhillbilly]

gx style lawnmower carbs are simple.

Only two circuits where you can tune.

By my count, you missed 4 other things that can be adjusted.
If you were to say easily adjusted, then I would agree with you.

For courts purposes though, those would be insignificant.

 

[FreeRunner15]

Was this with the 307 cam. That cam needs a 5k idle / clutch stall speed.

.380

How many people would watch me do a 5k launch with a .380 cam?

My predictions are i'll either backflip, or spin everywhere.