Dual 44mm Carbs on Superjet

[Doug997]

I wanted to ask you about switching the stock 38's for 44's. I understand that there's a need for a second pulse line to be added. Is this something that GroupK could do?

[Allistah]

Re: Dual 44mm Carbs on Superjet

What mods do you have on that engine?

[Yamabooeey]

Re: Dual 44mm Carbs on Superjet

You can drill cases yourself and install a pulse fitting. I have also use a "Y" before with only one pulse fitting.

[Doug997]

Re: Dual 44mm Carbs on Superjet

What mods do you have on that engine?

No mods yet. My plan is to buy a Factory Pipe, have the head milled a little bit so I can still run pump gas, and then add the carbs last.

[Doug997]

Re: Dual 44mm Carbs on Superjet

You can drill cases yourself and install a pulse fitting. I have also use a "Y" before with only one pulse fitting.

Hey Norm- I would love to do it myself but I do not have the garage to do this work in. I'm a little "handicapped" when it comes to garage space here in North Carolina. I have most of my tools in Las Vegas.

[Allistah]

Re: Dual 44mm Carbs on Superjet

From what I remember, Harry said that there was very little to no difference in switching from dual 38s to dual 44s. You might actually lose some bottom end by doing that.

I have a 701 Hammer kit from GroupK and I run the recommended single 44. The thing completely rips and I regularly pull away from stock 800 Skis.

To effectively use those 44s, you would have to have some aggressive porting and I'm still not sure it would be worth it. You may want to read all the docs on GroupK's site on all of the SuperJet testing they've done. It will save you a lot of time and money in the long run.

Here is a tip I learned: Follow their recipes to the letter. You'll be really happy with the results. I love my Hammer kit - I'm not touching it - and the stock single 44 on it.


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[Yamabooeey]

Re: Dual 44mm Carbs on Superjet

Hey Norm- I would love to do it myself but I do not have the garage to do this work in. I'm a little "handicapped" when it comes to garage space here in North Carolina. I have most of my tools in Las Vegas.

You can do this if you have a reed spacer. Or someone with a drill press can drill it out for you.

http://www.adaracing.com/personal-watercraft/kawasaki-800-angled-reed-spacers-3-degree/31-1303

[Group K]

Re: Dual 44mm Carbs on Superjet

Many thanks to those that chined in before I got to the post. In general, we have gotten great results from the dual 44s (from the 760/Blaster2) on the 845 big bores. However on all the smaller bore setups (81mm-86mm pistons) the modified dual 38s have pretty consistantly given the best combination of acceleration and fuel range.

If you do fit the Blaster2 dual 44 carbs, you will need to put in the second pulse line. We have seen guys that have tried to drive both fuel pumps with a single pulse line and a "Y" fitting .... but such a setup will struggle to drive both pumps effectively at higher rpms.... we advise against it. We also advise against reed spacers on any SuperJet setup.

Respectfully, Harry Klemm

I wanted to ask you about switching the stock 38's for 44's. I understand that there's a need for a second pulse line to be added. Is this something that GroupK could do?

[Allistah]

Re: Dual 44mm Carbs on Superjet

Looks like I was on the right track with my post. Looks like you'd be better off sticking with the 38s.

[Doug997]

Re: Dual 44mm Carbs on Superjet

Looks like I was on the right track with my post. Looks like you'd be better off sticking with the 38s.

Thanks for your advise.

[Doug997]

Re: Dual 44mm Carbs on Superjet

Many thanks to those that chined in before I got to the post. In general, we have gotten great results from the dual 44s (from the 760/Blaster2) on the 845 big bores. However on all the smaller bore setups (81mm-86mm pistons) the modified dual 38s have pretty consistantly given the best combination of acceleration and fuel range.

If you do fit the Blaster2 dual 44 carbs, you will need to put in the second pulse line. We have seen guys that have tried to drive both fuel pumps with a single pulse line and a "Y" fitting .... but such a setup will struggle to drive both pumps effectively at higher rpms.... we advise against it. We also advise against reed spacers on any SuperJet setup.

Respectfully, Harry Klemm

Harry, thank you. Can you tell me what kind of mods I can do that would be helpful?

[rdrttoy]

Re: Dual 44mm Carbs on Superjet

Dual 44s will provide the most power. I've tried both the 38s, modified 38s, and dual 44s. The dual 44s make noticeable power over the modified 38s. If you carefully read Harry's post he said the modified 38s provide the best overall power and fuel consumption (not the best power). The 44s are a tad bit thirsty, but it's worth it. I ran dual 44s on my super jet for a while and loved them (I now run dual 46s). I also run dual 44s on my girlfriends wave blaster, she loves them too. You just have to justify the fuel consumption for the power gain. More power generally takes more fuel.

Doug, I'm sure one of your riding buddies can help you with a second pulse line. Just bring them a six pack and you will be all set. I have an extra OEM pulse fitting if you need it.

[spdwrx701]

Re: Dual 44mm Carbs on Superjet

I also used stock 38's, taper bored 38's then 44's with the boyesen manifold/reed set up. Ski was a non ported Speedwerx dry piped limited... It ran excellent set up like this. 44's were a significant upgrade even on non ported engine... Fuel consumption still less not bad at all IMO. I will also add I think the manifold set up helped a lot not just the carbs

[JSNate]

Re: Dual 44mm Carbs on Superjet

I know this is an old thread. But.. I have a related question. I am running a ported 760 Blaster 2 engine in one of my Air Blair Darts. It does have the OEM dual 44's with dual pulse lines. Other than the porting, it has a Protec Pipe and Protec head. The 760 runs very well and strong. My question is regarding the best way to feed the fuel to the 44's? Currently I have a Cold Fusion fuel pick up with a dedicated fuel line to each Mikuni 44 and I just rebuilt the carbs as well.

1. Does an OEM 760 engine like this 760 run a single feed fuel line that is split to each carb?
2. Or are they set up from the Yamaha factory with a single dedicated fuel line to each carb?
3. Given my engine set-up what are most of you doing regarding fuel lines? Single feed, split? Or separate lines? And why?


Thanks for your input!

Nate

[swlamarshrunner]

Re: Dual 44mm Carbs on Superjet

3. Given my engine set-up what are most of you doing regarding fuel lines? Single feed, split? Or separate lines? And why?


Thanks for your input!

Nate

I make my own dedicated feeds..... I put same length fuel line onto the stock metal pickups and have fuel clunks at the bottom of the line. Acts as a filter and also has a spring/ball valve that keeps the lines loaded with fuel. I do it because it's cheap and effective. This pic is from a triple HX pickup I did, but essentially the same thing.

10 by Ricky Hinch, on Flickr