- Location
- Cruising Around
Well put
Freestyle Wanting more bottom end power
- Thread starter 'kotajoe
- Start date
Midlake Crisis
Site Supporter
- Location
- Bakersfield, CA
I read somewhere that a single carb is better for low end because the same volume of air is moving twice as fast to get through the single carb. Truth or fiction?
chriselmore_1
high on resin
- Location
- san jose ca
Cologne, a fresh haicut, and some crispy clothes are some cheap and easy mods to help you get more bottom end. 
1st-Put a dam FCV in tomorrow
2nd- you still on stock reeds/intake? if you are you could plug the crossover, helps create stonger signal strength for your carbs...not sure if you can do it with stock carb set-up tho....Ive never actually run stock carbs
3rd-MSD,Epic or advance your timing stock electronics just suck
4th-dont go bigger then 44 on that set-up there is such a thing as too much carb
2nd- you still on stock reeds/intake? if you are you could plug the crossover, helps create stonger signal strength for your carbs...not sure if you can do it with stock carb set-up tho....Ive never actually run stock carbs
3rd-MSD,Epic or advance your timing stock electronics just suck
4th-dont go bigger then 44 on that set-up there is such a thing as too much carb
Midlake Crisis
Site Supporter
- Location
- Bakersfield, CA
Doesn't the intake manifold take the number of cylinders out of the equation?
If so you are left with a given CFM of air having to flow through either one carb or two,
with the area of opening for air to flow through as Pi x Radius of opening squared:
38mm carb: 3.14 x (19 x 19) = 3.14 x 361 = 1133.54 sq mm x 2 carbs = 2267.08 sq mm opening
44mm carb: 3.14 x (22 x 22) = 3.14 x 484 = 1519.76 sq mm opening
If the same volume of air is being moved wouldn't the velocity have to be higher through the single carb?
Midlake Crisis
Site Supporter
- Location
- Bakersfield, CA
I don't get why the number of cylinders matters if the total volume of air being moved is drawn through a single intake manifold. In other words, I don't picture the carbs alternating flow depending on which cylinder is pumping. I picture them sharing the flow of air with each stroke regardless of which piston is drawing down.Only one cylinder draws air at a time on a twin.
Think about it. One piston going up at a time (drawing air in). The other is going down, not drawing air in.
The velocity through the bigger single carb is lower.
total air volume drawn at any one time: 350.5cc (for a 701)
Total air moving through the single carb at any one time: 350.5cc
Total air moving through the dual carb setup at any one time: 350.5cc (but only through ONE carb)
The single setup has both cylinders sharing one bigger carb, but only one cylinder is drawing its volume of air through the carb at any one time.
The dual carb setup has one smaller carb for each cylinder.
A dual carb setup doesn't share flow between runners (the crossover tube flows a little, but not a lot)
And whether it's dual or single manifold, only one side runner draws air at a time (reeds)
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Nice to know, i sent my 08+ prop to get it re-pitched to 10/16 to impros and it turned out great.
I think you will find the Hooker 9/15 to be on the high side for all but the hottest 701. Get an 85mm nozzle and/or take some load out of the impeller.
Benefit to dual Carbs it they are direct as possible to feeding the motor with the gas/fuel mixture, for every degree in change of direction is equivalent too 9" of straight flow, ie a 90 degree bend is equal too 10' of "piping", with the single manifold your adding 5' of friction because of that extra 45 degrees (effectively slowing down the velocity of the air/fuel), guys try and make up for it with a bigger Carb but it doesn't work that way and Ive had too many drinks in me tonight to even attempt to explain it ha ha... imo 2 carbs are better
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Ok, so I installed my FCV yesterday and test rode it today. I did notice a small difference in the way it responded off idle and it sounded way cooler lol. I am gonna try to order an MSD enhancer this week. I am still on the stock reeds, what are the advantages of uprgrading to carbon reeds?
subhard
TITS OR GTFO
- Location
- anchorage ak
They give you more low end snap
chriselmore_1
high on resin
- Location
- san jose ca
Haaahaa! Hardly... if your looking for performance gaing look elsewhere
swapmeet
Brotastic
- Location
- Arlington TX
Did you dial in the FC yesterday also?
Really? When I went from stockers to vforce my ski was totally woken up. Do you mean just carbon petals but the same cages? Not trying to call you out or anything I am genuinely curious.
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No, didnt get enough time to ride before the storm came in.
Are you using just the petals in the stock cages or do you have different cages?