2013 Superjet Stock Airbox Screens/Jetting Questions

[Aviator_929]

So I've been out of the game for some time and decided to pull the ski out of mothballs to ride this spring/summer coming up as I have some new people to ride with.

It's a 2013 Superjet that I bought brand new back then and have about 40ish hours on it. All stock internals.

I've seen numerous threads about easy/good upgrades and a lot of them saying the stock airbox is best, so I'm keeping that, but also see a lot of various posts about removing some of the mesh screens, but none really in-depth on that topic specifically (not that it appears that complicated but still). I see that there are 3 screens together for each carb. Is it worth removing 1, 2, or any at all on an all stock ski since I'm already in there? and if so, is that going to change anything jetting/tuning wise? Again, all stock ski. MAY do a pipe & girdled head for higher compression @ 93 octane at most down the road if the interest and riding buddies remain, but for now, it will remain as is internally. Just wondering if it's worth doing, and if so, how many do I remove from each carb?

Thanks guys!

 

[TheBuzzard]

If the screens are restricting air flow, removing any screens will make it run lean. It's not going to increase power. If it's tuned right, don't dick with it. Or take screens out and try it. You can always just put them back in. Not sure on that stock SJ but all the idiots with kawi 750s put aftermarket arrestors on there and then it runs like crap. Too lean

 

[kevbo]

I know its conventional wisdom that removing the air filter and muffler makes everything faster, even when it doesn't. Leave the flame arrestor alone, its not hurting power.

 

[john zigler]

We run stock boxes with one screen per carb. I also remove the chokes, and add a primer for improved air flow. I leave the rubber elbow off as well.

Please know IF you want to do this, you will need to lower pop off, and jet up a little. Also your carbs are NOT adjustable for fine tuning. You will need to remove the brass tamper proof caps and add t-bar adjusting screws.

Is this going to be a big gain on a stock ski, no. BUT it is the little things that add up. Our engines are just air pumps. More air = more fuel = more power. On a stock ski with a milled stock head, timing advanced a few degrees, dried out stock pipe, and more air is a noticeable difference.

 

[Aviator_929]

Appreciate all the responses guys. Great group here.

 

[Aviator_929]

We run stock boxes with one screen per carb. I also remove the chokes, and add a primer for improved air flow. I leave the rubber elbow off as well.

Please know IF you want to do this, you will need to lower pop off, and jet up a little. Also your carbs are NOT adjustable for fine tuning. You will need to remove the brass tamper proof caps and add t-bar adjusting screws.

Is this going to be a big gain on a stock ski, no. BUT it is the little things that add up. Our engines are just air pumps. More air = more fuel = more power. On a stock ski with a milled stock head, timing advanced a few degrees, dried out stock pipe, and more air is a noticeable difference.

@john zigler , could you please send me a PM? For some reason, it won't let me message you even though I have messaged others. Thanks!

 

[john zigler]

@john zigler , could you please send me a PM? For some reason, it won't let me message you even though I have messaged others. Thanks!

Sorry, I do not accept PM's here. It is just become too difficult to keep up with everyone in all the different places (Here, PWCtoday, face book, emails etc)

Please feel free to either call me at my shop during hours, or email me direct. All of my contact info can be found below in my signature, or at my Watcon web site.

 

[SteveC]

I think the honest thing to say is any/all “free upgrades” are not, actually, worth it. Like redrilling the steering nozzle to move the cable attachment 1/4” closer. Stuff worth doing is going to cost some money, perhaps small, right away. To start, pulling the carb adjuster plugs out and putting in T handle adjusters. From what I understand, a stock ski is tuned too rich from factory, so changing jets and tuning adjusters is a lower cost “must do” right away. While in there, rebuild each carb, cuz 11 yrs old with gas sitting in there is probably(?) problematic. Also remove chokes, if you like. Primers are supposedly superfluous on a properly tuned engine, so skip that maybe? Then, if you're going to do all that anyway, that’s the time to pop screens out leaving one. Will it be OMG AWESOME!! change? No, but maybe it’ll start easy and idle right.

FWIW, I support the “just ride it til I’m sure I have a group” mindset.

 

[Aviator_929]

I think the honest thing to say is any/all “free upgrades” are not, actually, worth it. Like redrilling the steering nozzle to move the cable attachment 1/4” closer. Stuff worth doing is going to cost some money, perhaps small, right away. To start, pulling the carb adjuster plugs out and putting in T handle adjusters. From what I understand, a stock ski is tuned too rich from factory, so changing jets and tuning adjusters is a lower cost “must do” right away. While in there, rebuild each carb, cuz 11 yrs old with gas sitting in there is probably(?) problematic. Also remove chokes, if you like. Primers are supposedly superfluous on a properly tuned engine, so skip that maybe? Then, if you're going to do all that anyway, that’s the time to pop screens out leaving one. Will it be OMG AWESOME!! change? No, but maybe it’ll start easy and idle right.

FWIW, I support the “just ride it til I’m sure I have a group” mindset.

That makes a lot of sense. Thanks for the insight @SteveC , Much appreciated!

 

[Roseand]

Keep the chokes. You're not gonna make much more power ditching them on a stock ski. Just something else to go wrong. If you're injesting a lot of water or riding surf I'd recommend a primer but otherwise chokes suffice.