RuiXing Carb questions

rab3rd

New member
First let me say that Im glad the site is back up, and sad to see all the data that was lost. I hope the DB's were not lost altogether.

So the questions. Im new to the BSP Clone racing sprint world. The racing club to which I belong uses pretty much the AKRA BS rules for sprint racing with a flywheel difference. There are weight categories that require different restrictor plates. The max bore on the carb is .615 and if you and your cart weight more than 405 pounds you can run without a restrictor plate. If the weight is more than 362 but less than 405 you must run a plate that reduces the opening to .550, and finally if the weight is less than 362 you must run a plate that reduces the opening to .500

From ARC the race ready blue printed carb setup for no restrictor comes with a .22 idle jet and .38 main jet. I assume that the Etube is stock and untouched. If you add the .550 plate the carb comes with a .21-.22 idle jet and a .39 main.

So my first question is, if you are reducing flow (.550 plate) and the main jet goes up to a .39 wont you just be putting your engine in a more rich setup? Or does the hole get smaller as the number gets bigger? (I dont think so but Im not certain)

Now, on the Etube it can be a max of .066 ID. I dont know what stock Etube ID size would be but IM guessing its smaller than .066. The Etube has two lower holes and 20 (I think) upper holes and that is a tech item too.

The question, Is it worth reaming the Etube to max if Im already restricted on flow overall? What will I gain if I do enlarge it?

Other questions.

What has the most effect on bottom end in the tuning? How can I get more pull out of the corners?
The holes in the Etube, are the bottom ones for idle and the top ones for mid to top range?

Thanks in advance for any help

Rob #5
 

kcracing

New member
you do jetup for a plate motor. jmo get in touch with dover power the holy moses carbs are setup for each plate and will out perform any carb out there.
 

rab3rd

New member
I am restricted to either the ruixing or huayi carb. No others are allowed.

So you jet up as in you pull more gas, that seems backwards to me since you have reduced air flow. But thats why Im here, trying to learn. ;-) Thanks for the response.
 

JPR57

Member
You will "typically" go up on main jetting with a restrictor plate because the plate is behind the venturi of the carb and will cause turbulence between the butterfly and plate. This will cause the carb to have a lower fuel signal. The Etube is stock but not untouched, the center hole is .0635/.064. If you do ream it be sure not to leave any swirl marks because that will get you tossed at most tracks. If you have any more questions feel free to give us a call.
 

rab3rd

New member
You will "typically" go up on main jetting with a restrictor plate because the plate is behind the venturi of the carb and will cause turbulence between the butterfly and plate. This will cause the carb to have a lower fuel signal. The Etube is stock but not untouched, the center hole is .0635/.064. If you do ream it be sure not to leave any swirl marks because that will get you tossed at most tracks. If you have any more questions feel free to give us a call.

Ah, I see. I was just pondering the idea of the restriction being after the venturi. Why would reaming get one tossed? If they spec a max ID and test with a NO GO would that not imply that a mod is legal up to the spec'ed max?

And to that I would add, why doesnt the plate live in the other side of the venturi?
 
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Kart43

Member
The center hole in the Etube if copied from Honda would be a max of .066" I think if you check many clones you will find some brands are up to that size. The etube bore is quite a bit larger than the jet so reaming it will have very little effect. The holes atomize the fuel they break the liquid up by introducing bubbles of air, no they are not designed to affect idle mixture that is done by the idle circuit.
 

rab3rd

New member
answered my own question about the rule.... "Stock emulsion tube must be used and unaltered, .066’ max ID"
 

kcracing

New member
^^^^^ what he said...... That why i buy my done by a professional carb builder, open the box and it legal and ready to go.heck most the time i dont even have to mess with the idle.
 

rab3rd

New member
Well mine is done by professionals, ARC Racing but it was ordered setup for no restrictor plate and I have since had to add the plate because I dont meet the unrestricted weight. That got me needing to re-jet which then got me to thinking about what else can I do. If you aint thinking you aint tryin, right?

Thanks for all the responses.

Rob
 
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