Dual 38's to Single 48? Should I do it?

[nightrider05]

Picked up a 99 SJ yesterday..Has Protec exhaust but other than that its stock. Previous owner was trying to fix a stuck choke and ended up screwing one of the carbs up..he attempted to drill the soft screws out and its nearly impossible to get the remainder of the bolts out.

I have a Mikuni SBN 48mm carb sitting here...not sure what its from or if its modified...Just wondering if that carb would supply the motor with enough fuel? Or should I put a set of stock Dual 38's back on it? I realize I would need to get an aftermarket intake manifold for the single 48.

I have a stock set of dual 38's laying around if not..not a big deal. Also have a stock set of dual 44's sitting here.

Thanks for the help in advance!

 

[Polish jet pilot]

It is common mod to change duals to big single, especially for FS and Freeride applications where water ingestion is quite possible. Plus a well tuned single carb will probably give more hit (somebody chime in here) than 2 small carbs - however top end performance may suffer a bit...(chime in again)...

 

[nightrider05]

It is common mod to change duals to big single, especially for FS and Freeride applications where water ingestion is quite possible. Plus a well tuned single carb will probably give more hit (somebody chime in here) than 2 small carbs - however top end performance may suffer a bit...(chime in again)...

Great information. I have a couple of exhaust options for my SJ..It has the protec exhaust currently on it but I have a Factory B sitting in my spare SJ right now.

I had also read that you lose a bit of top end with this mod, but im not too worried about that. I want good low end power.

I appreciate your insight on this. I am currently looking for an aftermarket intake. I will probably put another set of dual 38's on it just so I can ride this weekend..but after that would like to try my setup.

 

[Mark44]

No question IMO Duel is the way to go.

Mark44

 

[Matt_E]

It is common mod to change duals to big single, especially for FS and Freeride applications where water ingestion is quite possible. Plus a well tuned single carb will probably give more hit (somebody chime in here) than 2 small carbs - however top end performance may suffer a bit...(chime in again)...

Just my opinion: The tidbit about less water intrusion in a single carb is a myth, in my experience. I now run Pro-K's without outerwears on my motor (dual 46 carbs) and have zero issues with water getting in them. Absolutely none. That includes surf and flatwater freestyle-bumbling.
They key is to have a good hoodseal & hood to keep the water out to begin with.

 

[nightrider05]

No question IMO Duel is the way to go.

Mark44

Dual stock or aftermarket?

Just my opinion: The tidbit about less water intrusion in a single carb is a myth, in my experience. I now run Pro-K's without outerwears on my motor (dual 46 carbs) and have zero issues with water getting in them. Absolutely none. That includes surf and flatwater freestyle-bumbling.
They key is to have a good hoodseal & hood to keep the water out to begin with.

Yea either way a motor is pulling in air from outside..if there is water in the hull it will pull the water in no matter if you have 1 or 2 carbs. I will be running a good bilge pump setup so im not worried about that part of it.

I wont be dropping the coin on dual aftermarket carbs...so right now im really just looking to find out if running a Single 48 vs Dual 38's will be beneficial with my setup.


I have those Dual 44's I thought about tossing on..not sure what that would give me thought. On a virtually stock motor that might be over kill.

 

[Mark44]

If stock motor 701 38's if ported 44's. I have after market 44's om my ski.

Mark44

 

[steveyz250fpilot]

Try different setups...... and give us your thoughts!!

 

[Big Kahuna]

If your running a stock porting, your gonna be hard pressed to find a better setup than the 38's. Those carbs were designed specifically for that motor. One of the strongest SJ's that I have ever ridden was one ported by Wamiltons and had dual 38's.

I would stick with 38's.

 

[Kirv]

he's really asking "hey my dual 38's are messed up, can i run a single 48 and get enough flow?"

the answer to that is yes, you will get enough flow. i run a single 48 novi gen III on a big bore motor.

there are those that say single rules, and those that say double rules. there are more in favor of the doubles, but the bottom line is they both work great, and you can use a single 48 for your setup. you might have to experiment with the jetting to get it right, bigger jets than in the dual 38 no question.

that said, i've ridden a "can't modify it anymore" 701 that was using stock dual 38's and it was awesome.

 

[nightrider05]

he's really asking "hey my dual 38's are messed up, can i run a single 48 and get enough flow?"

the answer to that is yes, you will get enough flow. i run a single 48 novi gen III on a big bore motor.

there are those that say single rules, and those that say double rules. there are more in favor of the doubles, but the bottom line is they both work great, and you can use a single 48 for your setup. you might have to experiment with the jetting to get it right, bigger jets than in the dual 38 no question.

that said, i've ridden a "can't modify it anymore" 701 that was using stock dual 38's and it was awesome.

Yea you nailed it with that..I located a Riva intake manifold and spacer for a pretty good deal..I am going to run the dual 38's for now and then experiment with other setups.