accelerator pump or none on carbs

[jcp123]

I'd go with a small accelerator pump...most carbs probably dump too much fuel.

[oil pan 4]

About the only thing you will find with a carb that will work with out an accelerator pumps a chain saw. You rev them up to speed at almost no load and go to work, unlike a vehicle that has to do a lot of work to accelerate you up to speed.
Another way you can run with out an accelerator pump is to run your carb catastrophically rich.

Years ago I set my Camaro to run a lean idle after I installed a wide band O2 gauge. One day I was changing out accelerator pump jets and forgot to reattach it to the linkage. I started the car, put it in drive and as soon as I touched the gas it died and I figured I forgot to reattach the accelerator pump more or less immediately.
Now a few years before that, I was messing with that car, when it was running really rich before I had a wide band O2 gauge and deluxe carb tuning set and disconnected the accelerator pump to see if it would go and it kind of did. But it was more or less undriveable with no accelerator pump.

[adam728]

Originally Posted by oil pan 4

About the only thing you will find with a carb that will work with out an accelerator pumps a chain saw. You rev them up to speed at almost no load and go to work, unlike a vehicle that has to do a lot of work to accelerate you up to speed.

You'll be hard pressed to find any 2 stroke out there with an accelerator pump, not just chain saws.

[johnathanf1lm]

sorry to revamp an old tread but i have rebuilt my carbs 2 times already and i still have a gas leak at the accelerator pump cover and area. im at about wits end with this carb. lol sadly i sold the donor no pump carb. if i went with a new donor bike without a accelerator pump what should i adjust to make it work (carb jetting etc .

[jtbo]

Originally Posted by oil pan 4

About the only thing you will find with a carb that will work with out an accelerator pumps a chain saw.

Some 4-stroke scooters don't have accelerator pump, I guess design is adjusted to that.

I have one of such carb, it doesn't die when giving throttle, there just is not much happening, not even at WOT.

Slide in that is huge, but throat is much smaller than what slide is, it is like if they would of put twice too big slide to that carb.

When exploring world of cheap chinese scooters, there are no thing that is impossible, no matter how much against logic some design is, some of them has tested it and managed to sell who knows how much of that junk.

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If there is a leak near accelerator pump, is it sure that it is not the shaft that goes to pump which is worn so that it leaks from there and then just run off to area of cover?

[johnathanf1lm]

the design is its built into the carb float bowl. its leaking when i pump the throttle even when its not running. and its leaking from the cover. i am going to give it one more try and replace the pump again and this time take the float bowl and clean the crap out of it. or maybe ill buy a new float bowl to see if maybe it cracked

[renault_megane_dci]

If there is no actual accelerator pump, there is an inbuilt system doing the exact same purpose like on CV carbs with the raise of the needle is slowed down when the throttle is opened so that the engine draws more fuel due to being air starved.

[cRiPpLe_rOoStEr]

Most motorcycle and small stationary engine carburettors I've messed with had no accelerator pump. Anyway, after seeing some older cars getting adapted with motorcycle carburettors, I wouldn't be so worried about not having an accelerator pump.

[user removed]

I always like the Hitachi SU types on the first 1970 Datsun 240z (11-69 first month produced).

Float height check using a small plastic straw down the vent hole in the float chamber.

Choke just dropped the seat where the needle moved, no real choke butterfly.

Throttle response was magnificent when they were set up right.

Different tapered needles for different performance parameters.

Two adjustments, the same seat the choke moved and the viscosity of the air chamber oil, with ATF the lightest.

Plugs ran as clean as fuel injection and mileage was as good or slightly better.

It did have a summer winter flap, manually adjusted only from the engine compartment, that you had to use when it got below 40-50 or it fell flat on it's arse when you hit the gas in winter.

You could set it to run too lean, then just add some choke for more power (redneck lean burn).

regards
mech

[cRiPpLe_rOoStEr]

Those Hitachi, SU, Stromberg-CD and Keihin-CV carburettors are awesome.