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Post by dude on Mar 7, 2011 18:42:41 GMT -5
I was wondering why some 50cc 4stk's have them and some don't ? I understand why they may need to be there.
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Post by felliott on Mar 7, 2011 19:13:13 GMT -5
I feel that some do not is to keep prices of carburetors down. It is also one less thing to have problems. But I believe all of the carburetors should have them.
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Post by stepthrutuner on Mar 7, 2011 20:28:24 GMT -5
Do all CV carburetors not have accelerator pumps? I guess I haven't seen one that doesn't yet?
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Post by 90GTVert on Mar 7, 2011 20:32:39 GMT -5
Not all of them do. I don't think any of the 150 carbs do. I know I looked for a 150 carb with a pump for my 80cc and didn't see any at a reasonable price. The ones I saw with pumps were aftermarket and more expensive.
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Post by Goosey on Mar 8, 2011 8:55:54 GMT -5
LOL, so that's why I was thinking, "Accelorator pump?" I don't think I have one then in the 150's.
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Post by rocketdog on Mar 8, 2011 12:35:19 GMT -5
This OKO 26mm has one.  They can be a little pricey. RD |
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Post by reveeen on Mar 9, 2011 15:24:08 GMT -5
I understand why they may need to be there. They (accelerator pumps) give a shot of fuel on carburetor opening. This allows you to run the engine lean (for fuel mileage and emissions) under most conditions (other than "warm up" when the choke is working), giving a shot of fuel when needed (acceleration), eliminating engine stumble when lean. (emissions are tested at a constant engine speed, so the incorporation of an accelerator pump is a way to run a lean mixture without the resulting engine stumble (bog) and still pass emissions) Not to be confused with a "power jet" (commonly referred to as a "power valve"), that introduces extra fuel into the venturi during times of high air flow. The downside to running a engine under a lean condition is heat. Something rather important to consider in an air cooled engine. So, personally, I'll run my engine with a bit of a too much fuel (rather than too little), thank you very much. |
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Post by Goosey on Mar 10, 2011 8:59:31 GMT -5
So good for emissions, bad for the engine. Thanks for the information. I definately do not have an accelerator pump on either of my 150cc carbs. As we don't have mandatory tests around here yet, sounds like something not to spend $ on for me.
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Post by reveeen on Mar 10, 2011 16:43:54 GMT -5
So good for emissions, bad for the engine. You can encounter an accelerator pump on a carburetor that is just too big for a given application. You see this on Harvey Dumbikes with 45mm+ carbs. Cracking the throttle wide open resulting in minimal air flow (the air is moving too slow to pick up enough fuel as it passes the main jet). This is not supposed to happen with a vacuum carb though, as the piston only raises with a corresponding amount of engine/intake vacuum. |
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