Carbs: What makes a 44MM Blackjack better then a 4MM Mikuni Super BN.

[Roo]

The drivetrain I am currently running was a direct swap into my hull and came with Dual 44MM BlackJacks. Why would someone want to run these oppose to OEM 44MM Mikuni Super BN carbs?


Doesn't the BlackJack 'begin' life as a Mikuni?

I am just looking for technical differences but don't know where to look.

Thanks ya'll!

Regards,
Andrew

 

[Flat Brapp]

I believe the inner circuitry may be modified for better response and so on.........But im no genius about carbs.

 

[Roo]

I believe the inner circuitry may be modified for better response and so on.........But im no genius about carbs.

Ok, going on that logic, is the circuitry inside preferred for racing applications or freestyle applications?

 

[tom21]

well it has the top chopped off and a bell pressed on that replaces the bombsight where the fuel enters which has lots of holes (10?) that now supply the fuel.

check the site, if you believe the hype then it sums it up pretty well. I have only seen them never had em under my feet. someone else can tell you if they are worth the money.

/www.jetworks.net/blackjack1.htm

 

[crammit442]

The drivetrain I am currently running was a direct swap into my hull and came with Dual 44MM BlackJacks. Why would someone want to run these oppose to OEM 44MM Mikuni Super BN carbs?


Doesn't the BlackJack 'begin' life as a Mikuni?

I am just looking for technical differences but don't know where to look.

Thanks ya'll!

Regards,
Andrew

They do as do full spec, novi, riva, etc. They use an annular discharge design rather than the traditional bombsight. They flow a lot of air because of the open design and pull fuel easily because of the low pressure area built into the billet top. I've had good success with them and find them to be easy to work with. If I had a well tuned boat with ful spec, Novi, or whatever I would not replace them with BlackJacks. Most of the carbs that we use can be tuned to work well if you figure them out. I personally think they work as well as anything on the market and better than most, but for me it comes down to being able to work with the carb designer for tuning help. Brazina, Tim(Novi), Art, etc. all have good reps for being able to get you dialed in pretty quickly when you need help.

 

[Big Kahuna]

They do as do full spec, novi, riva, etc. They use an annular discharge design rather than the traditional bombsight. They flow a lot of air because of the open design and pull fuel easily because of the low pressure area built into the billet top. I've had good success with them and find them to be easy to work with. If I had a well tuned boat with ful spec, Novi, or whatever I would not replace them with BlackJacks. Most of the carbs that we use can be tuned to work well if you figure them out. I personally think they work as well as anything on the market and better than most, but for me it comes down to being able to work with the carb designer for tuning help. Brazina, Tim(Novi), Art, etc. all have good reps for being able to get you dialed in pretty quickly when you need help.

What he said.......... It all about the package.

 

[keefer]

Keep the Blackjacks!! Like crammit said they are one of the top 3 of modified carbs. I have personally ridden several boats with them and if tuned properly they hit and run great. I have Full spec 48s and a couple of other guys in my area have Novi 48s and Blackjack 46s. All of these boats make great power throughout the band and are most certainly better than OEM carbs.

 

[Dustin Mustangs]

I am wondering if anyone has felt the difference (back to back) between dialed OEM and aftermarket carbs of the same size. Just because they are different doesn't necessarily mean they are better, no?

 

[Big Kahuna]

OEM jetting circuits are much different than the Circuitry that comes in the Mikuni SBN's that Novi, Full Spec, Blackjack. They are more concerned with emmisions and what not......

 

[WFO Speedracer]

The oem and aftermarket Mikunis have way different fuel circuitry,unless you do an extensive mod like the Blackjack mod you are pissing in the wind with stock carbs for serious freestyle usage!

 

[SUPERJET-113]

I am wondering if anyone has felt the difference (back to back) between dialed OEM and aftermarket carbs of the same size. Just because they are different doesn't necessarily mean they are better, no?

They are WAY better. I just did that exact back to back test:
http://www.x-h2o.com/threads/40081
I call them BrapJacks! :headbang:

Art ---->:bow28:
lol

 

[kevbo]

The drivetrain I am currently running was a direct swap into my hull and came with Dual 44MM BlackJacks. Why would someone want to run these oppose to OEM 44MM Mikuni Super BN carbs?


Doesn't the BlackJack 'begin' life as a Mikuni?

I am just looking for technical differences but don't know where to look.

Thanks ya'll!

Regards,
Andrew

Those Blackjacks have had the venturi cut out of them for higher airflow. That hurts fuel draw but is often ok with dual carb setups. The barrel-roll guys have unique needs where oversize carbs are an asset. If you have no intrest in rolls and flips then a standard 44 or smaller carb is usually better.

 

[2XLR8]

It makes you wonder how a carb that has no bombsight at all still works pretty darn good. When you have a set of carbs perfectly dialed in they should Idle for more than 30 seconds and you should grab a handfull of throttle and it should just take off with out a skip or sign of loading up. If your carbs do that then you have a good set up and a good set of carbs. I wonder if changing your booster venturi design really makes that much of a change. I have seen annular discharge boosters, half covered boosters then open boosters and now open boosters cut in a series of small holes to create a new design. Hey what ever it takes, as long as it works good .

 

[Kennay]

I wouldn't use anything else again. I haven't used Novi's, Riva's, or FS, but I can't imagine it getting any better. SO crisp, clean, never load up.... what more do you want?

 

[Goose]

oem carbs fuel signals are horrible without being modded the booster design is horrible.however if you modify the booster i have stumbled across a 25% increase on fuel signal and increasing the flow rate thrue the venturi.this made me drop 4jetsizes in the main creating a smaller fuel droplet making them more responsive

 

[Melmack]

I have a set of thease, besides arm ripping response, they look realy cool when you're tuning them with the flame arrestor off. BTW, you'll be looking at them this way a lot. They hit realy hard bottom end with a mod or limited setup. They can dump more fuel than any other carb I've seen. Don't use them if your settup requires little fuel. If you have porting or a b pipe minimum, they'll be ok but setup takes a while. Low pop-off was helpfull with mine.

 

[WaveDemon]

fyi There are 2 versions of mikuni carbs, the ones you can buy from mikuni (good) and the kind that come on ski's from yamaha/seadoo/kawisaki - OEM (not so good). generally aftermarket companies start with carbs from makuni not OEM's.

 

[SUPERJET-113]

When it comes to making a set of BrApJacK carbs Art told me that it didnt matter which he started with(OEM or after market Mikuni). He said they brap equally as well when he is done with them. So that is a great thing!!

 

[jetpilot08]

Lets say you have two 44 mm carbs that came from a single carb application...could you fire those off to Art and have them turned into a rocking Blackjack 44 mm dual carb setup?

 

[blaster800]

oem carbs fuel signals are horrible without being modded the booster design is horrible.however if you modify the booster i have stumbled across a 25% increase on fuel signal and increasing the flow rate thrue the venturi.this made me drop 4jetsizes in the main creating a smaller fuel droplet making them more responsive

correct me If im offbase but : fuel is not atomzed right after leaving the main jet , it must pass through the holes that open into the venturi , which is the exact point of atomization , the jet will only controll the volume of fuel avaiable to pass through the ''venturi holes'' to become atomized , so Im confused how a different jet size can create better atomization or am i not seeing the pic here .