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So I want to put a bank of r1 carbs on my l20b swapped 510, but ive seen a video of these guys that pushed 207hp using dual weber side draft carbs. Now i'm wondering how much power can you push threw the r1 setup. I understand the r1 carbs have a way faster throttle response and rev but whats the power gains?

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1 minute ago, banzai510(hainz) said:

does a R1 carbs have a power valve or accel pump?


i highly dought your going to get 140 to the ground anyways unless you have a big cam , ported head high comp built motor


My l20b is bored 15mm over stock with full forged internals. with a machined and ported u67 head

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Hainz, no they don't have a power valve or accelerator pump or choke though there is an enrichment circuit for starting.. They are similar to SUs .


One thing for sure they have great throttle response, by that I mean smooth power from idle up. If you suddenly floor it the carbs do not suddenly slam open and gasp for air. They open as the engine revs up and needs more air. One thing is the air entering horizontal just goes right into the intake ports on the head. There is no loss from making a 900 bend like on a down draft. I can look into the carb and see the intake valve. Second, they have one carb for each cylinder so you can easily tune the runner length. Each are 1.5" (give or take) so lots of air flow. 


The Hitachi was slow above 4K, took forever to get to 5K. With the R-1s it screams right past to 6K.



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Honest Hainz you don't need accelerator pump. The slide lifts in proportion to engine need for air. The air flowing past the needle is at a constant speed. It doesn't open with the pedal, so it doesn't need a squirt of fuel to get through than bog point. If at 1,500 in forth and you floor it it, just goes, no bog, no flat spot, no hesitation. It just begins pulling smoothly away and good torque too.

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