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Discussion Starter #1
i work at a motorcycle shop and can jet bikes and quads pretty easily ... BUT its harder to do it the same way with my truck so, how you guys do it??

When cruising around 1800 rpm and then step on the gas, it doesnt cut out or really stumble but after a split second it picks up power buy about 50% more, like maybe i need a little more accelerator pump??? it doesnt bog so it must be close i would think.... unless its like vacuum advance??
 

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If its a vacuum secondary carb like a Holley, you may need a lighter spring in the vacuum pod. It controls the rate at which the secondary throttle blades open up.
 

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good call it is vacuum secondarys, would it be better to just make them stay open the whole time rather then be slow?
i guess it only effects it when i first hit the throttle so i could just wait and do it right
 

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Discussion Starter #7
wouldnt a heavier spring keep it closed longer? im tryin to decide if its the accelerator pump adjusted to much or to less, or if its them vac's
in nuetral it revs great, just on the road it hesitates

not to mention now i noticed a bad stumble around 4800, thats in nuetral no load, i know things are different without load but.....
might have something to do with when i have 100% throttle in a mud hole and if it bogs down to stall ill push the clutch in and it wants to stall. im thinkin to much fuel on top makes it stumble/gurgle and load up with extra fuel

sorry guess i had more questions then i thought, and i dont no much about the carb, i had it there so i used it, just a holley with vac's and one accel pump and 2 fuel screws
 

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You might want to stop by Barnes and Nobles or Books a Million and pick up a Holley carb book. They certainly arent harder or easier than a Mikuni once you know what does what and where systems overlap.

Or... fab up an adapter and mount some Mikunis in its place;)
 

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wouldnt a heavier spring keep it closed longer? im tryin to decide if its the accelerator pump adjusted to much or to less, or if its them vac's
in nuetral it revs great, just on the road it hesitates

not to mention now i noticed a bad stumble around 4800, thats in nuetral no load, i know things are different without load but.....
might have something to do with when i have 100% throttle in a mud hole and if it bogs down to stall ill push the clutch in and it wants to stall. im thinkin to much fuel on top makes it stumble/gurgle and load up with extra fuel

sorry guess i had more questions then i thought, and i dont no much about the carb, i had it there so i used it, just a holley with vac's and one accel pump and 2 fuel screws
If it stumbles when you floor it, then it needs more accelerator pump shot to cover the extra rush of air it gets when the throttles are suddenly smacked open.

If it does not stumble but is just slow and lazy to react, then you need to the lighter spring in the secondary vacuum pod.

If its stumbling when you are mud boggin, it may be fuel slosh coming out the vent tubes and going down the venturis.....simply put some small rubber hoses over the vent tubes to "extend" the vents.

You mentioned a clutch, so if its a stick shift vehicle, then a vacuum secondary carb is really the wrong one to have on there. It will work, but its not as properly matched to the application as a "double pumper" mechanical secondary carb would be.
 

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If it does not stumble but is just slow and lazy to react, then you need to the lighter spring in the secondary vacuum pod.

This is the tough call that we can't make sitting at a computer. If you can FEEL the carb kick in you need a heavier spring.

If as above it's slow to react and lazy go with the lighter spring.
 
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