Single vs dual carbs?

[maniac]

Looking at a ski and it has a single 48.
Never been around anything with this setup and wondering how well they preform compared to dual setups.
Seems to me that they world be less power but easier to tune?
Less CFM right?
Any input would be great. Power? top end? bottom end?
Thanks
Don

 

[550/440]

You've got it right. Power output can be debated, some say their single 48mm can hit as hard as dual 44's (or bigger), but that's so subjective that it's not really fair to compare without swapping out carbs on the exact same ski and doing an apples to apples comparison, and I've yet to see anyone do that in a thread.
How many pro built skis run singles?

 

[TheBuzzard]

1 equals less than 2. a single novi 48 swapped for stock 760 dual 44s = huge power difference. i laugh at anybody that says their single rips. you can sell a single 46-48 setup for more than you can buy a dual 44 setup for and thats a good thing. single has less power everywhere. some years ago most surf riders swore by a single. you dont need big power in the surf but it sure is nice. now everybody runs 1000cc motors in surf! too much is always better than not enough

 

[XJCrawler]

Everyone says there singles rip, until they try a set of well tuned duals

 

[ajmps1]

The appeal of the single is there are less things to break, im sure that single 48 will put a huge grin on your face just the same.

 

[TheBuzzard]

grins turn to frowns when you lose power

 

[bird]

I remember this debate when I went with 38s on my PP 550 8 years ago. Once I put them on, it was a clear difference from the 44mm I was running. I felt like the motor just breathed better all around, no other engine work was done in between the mod. It was already a high compression, full exhaust 550.

 

[maniac]

I'm sure it is something that will run harder then what I'm used to because of other mods but may want to update later. Just don't want something that will disappoint but a test ride before buying should be all I need for now I guess. Want to put more into another ski before this one parts wise.

 

[Vumad]

My X2 had a noticeable improvement in power changing from a single SBN 44 to dual SBN 44s last week.

It had a 10/18 straight prop on it that it was breaking free on the low and turning 7500-7800 RPM. I put a 14/19 big hub swirl in it and rode it with the single 44 with SJ airbox. I then put the dual 44 mikunis on it with K&N airbox. It's not dialed in on the top yet but it's still a noticeable difference compared to the single. Back to back with only changes being dual vs single and the airbox.

I know it's not the airbox, it makes more power everywhere. It's not a mind game from the exhaust noise, my X2 has a SJ waterbox and rear exhaust, throaty and quiet.

 

[Vumad]

Oh, I went from the single 44 to the dual 44s because Ryan bought a X2 with dual 38mm keihens on it. We didn't want to buy keihen stuff or learn to turn them, and Ryan is (was) a believer that a single carb is the way to go, especially in the surf.

His X2 had a 14/19 solas straight small hub prop. We changed from the dual 38mm keihens to the single 44 mikuni and lost power. The 44 was tried with every jetting and pop-off combination that could possibly make sense (and it couldn't possibly need to be richer than my X2 which has a much better pipe and significantly more power). We also went from black plugs with the 38s to light tan plugs with the 44. Adding more fuel to the 44 made no more power, we lost power, so lighter less safe plugs with less performance than untuned 38s. We got power back in the midrange by proping to my old 10/18 prop, but its still lacking in the top compared to the 38s. We also lost about 6mph compared to the bigger prop (49mph GPS with 38s with 14/19, 42 GPS with the 44 10/18.) The 44 couldn't push the 14/19 into the power band. The 38s got it to 7100 RPM on their own, but the 44 maxed out at 6800 RPM unless you unloaded the pump at which time it would get to 7100 and stay there.

I know it's not a perfect comparison because he's got the standard AM 650 pipe on a 750 motor like most X2 owners, but back to back carb changes showed less performance from a change to a bigger single carb.

He now wants to look into tuning the 38s or getting some 40mm mikunis.

 

[maniac]

I ended up buying it with both carb options. Spent a bunch of time tuning the single and nothing seemed to make any difference so I put on the twins and it ran way better. Just need to spend some time getting them a bit closer.

 

[Fx1 Love/SJ Love AZ]

i REALLY like my single carb setup on my Fx1, but its also just an fx1. the carb setup has alot to do with how you prefer to spend your day at the lake. dual carbs will always out preform a single. but the single carb ski will be the one towing the dual carb back to the launch for fuel if you try and rip around into the back of the lake with some buddys. if your motor is stock and its running duals it seems to get fairly close to the same distance on a tank, the ported beast motor with duals drink gas like no other. Funny thing is i definitely feel like my single rips. its also jetted 145, 112 (close as i could find to 120) and 90 gram spring. got the jets on a saturday night last second from a jetski rental shop that does yamaha stuff, and not to mention he gave it to me for free.

 

[So Low Roller]

i swaped my friends single carb to dual carb 750sx, he said it was "night and day difference"