Super Jet Need help carb tuning

[bondra131]

Anyone out there REALLY know how to correctly jet and tune carbs to an aftermarket build? Maybe someone has also already owned a ski built like mine and knows what configuration was best... Factory pipe can only tell what jet sizes to use if you run their pipe and ALL else is stock. That is no help to me at all... Please, someone who actually knows what they're doing, I really need help. Have a nice new motor here limited build and it does not run as hard as skis I've rode that are less built.. Of course, none of the local riders can help me out. Guess my ski is too complicated for them. Although, It's not all that built... Heh

 

[yamanube]

You will need to give more information (as much as you know) in order to get any help.

 

[iangdesign]

LOL...

What ski?
what year?
Complete engine setup?

Maybe the local riders couldn't help you cause you didn't give them any info either. Also the search feature here is pretty powerful, spend a little time and search for a similar setup.

 

[bondra131]

Local riders know what my ski is... 62t/61x ebox, stator and flywheel are out of a 6m6 650 motor. I installed the msd enhancer with the rev limit adjusted turned up all the way. Carbs are non modifed dual 44's that I recently put rebuild kits in and new throttle shafts and butterfly's. head is ada with 35cc domes. Exhaust is factory type 4 dry. Dual cooling is set up and functioning. Motor is stock 81.25 bore. No case or cylinder porting

 

[bondra131]

Also Running tornado flame arresters not an oem air box

 

[yamanube]

Check the tuning/carb spec data base here first but I would be willing to bet the FP instructions for the WB2 dry pipe would get you pretty close.

http://factorypipe.com/media/instructions/yamaha/760gp.pdf

 

[bondra131]

Factory pipe configuration is based off of dual 38's not 44's and oem head and oem air box. Flame arresters lower carb air pressure. Factory pipe also says to use oem needle and seat and spring and that's fine with oem air box. I do not have oem needle and seat and spring I am running 2.5 needle and seat with 115 gram springs

 

[yamanube]

That link I posted is to instructions for the WB2 dry pipe (760 with dual 44s). It might not be spot on but might be a decent starting point, don't assume because that is what NS and spring you have, that is what you have to tune to. Keyboard tuning can only get you so far, it sounds like you need to bring it to somebody who knows what they are doing.

Three easy steps to getting your ski tuned well:
1. Put the stock 38s and airbox back on
2. Tune to FP specs
3. Be happy

 

[bondra131]

Assume what ns I have? I installed the 2.5ns and 115g gold spring myself. Getting 38's would be easy. But I invested in the 44's and the nice r&d two piece intake manifold. Don't want to ditch this stuff and it can be done. I do need someone who knows what they are doing lol. I can build skis just fine. Tuning is another story.. And no one around here knows anything about em. Definitely not a popular sport here

 

[yamanube]

This is the difference between building a ski, and assembling a ski.

 

[Matt_E]

Eh there are plenty of capable tuners in the Spok/CdA area who've been doing it for years and years.

 

[bondra131]

Like who? No one seems to want to help me lol whether they know what they're doing or not. All they do is talk on each other and everyone says that everyone else doesn't know what they're doing when it comes to skis lmao

 

[bondra131]

So uh if anyone actually know how to set up skis, please reply... I'm not looking for worthless replies ha

 

[Poizen]

judging by the way you talk to guys here giving you advice its no wonder no tuners want to help you because im sure you talk to them the same way

guys have given you the base starting every motor/combo is diff everyone starts with a base setting and fine tunes from there every rider has a diff pref fiddle till you find yours

 

[CARBONX2]

So uh if anyone actually know how to set up skis, please reply... I'm not looking for worthless replies ha

Pop-off is about right, chart shows 19PSI
What jets are in them now? A good starting point is LS = 130, HS = 120. Start with LS-screw at 1turn and HS-screw at 1turn. Adjust screws individually and test to see if any changes to jetting are needed.
Have you checked the timing with a light to verify it is right?

 

[catpower]

dude I feel your pain, I see your from Idaho and i'm from Iowa. What I mean is NO one around here knows jack about the aftermarket world when it comes to pwc, especialy standups and blasters. Every time I go to the sport dealers and tell the guy behind the counter I own an HX and a Waveblaster he looks at me with dear in the head lights. I'm betting you own a sled though. I've had to teach myself about tuning as well. So take this for what its' worth. If you havn't read the Mikuni manual several times yet do so. Group K has good info as well. My recommendation and I don't mean to talk down to you but I would reinstall those 38's and then start tuning from idle to low speed circuit and mid range and then worry about main jet. Your not going to get much ridding in this way but this is how I would do it. This is slow and time consuming but well worth the knowledge you'll gain. Use that knowledge to know what it takes to use big carbs. The info for 38's is abundant. I too have an aftermarket intake but don't have the time to try bigger carbs. Make notes as to what works and what doesn't work. lol keep reading and have fun with it.

 

[bondra131]

Fiddling with it is a waste of time when there's so many combos that can be tried... 4 ns sizes. 4 different springs. And I'm not sure how it all works like does the ns size and stiffness of spring change what jet sizes you'll use? I don't know... Blowsions motor builder told me for my set up to start with 2.5ns and 115 gram springs, 120 pilot, 125 main. I ordered these parts and the springs that I got weren't gold which 115g should be. I ran the parts anyways and the jets (according to mikuni manual) were too big judging by the tests mikuni says to perform. So I dinked with jets and found that 112.5 works for pilot and 120 for main. Then rebuilt the carbs and rebuild kits came with black springs and gold. I popped in the golds to be sure they were actually 115g as I was directed to use with the 2.5ns. Ski doesn't load up or hesitate when cruising 1/4 throttle then pinning it and doesn't load up or hesitate when pinning off of 3/4 throttle. According to mikuni, this means my jet sizes are fine. And I have turned screws to get it to run the best I can yet it still doesn't run that well. It's decent but I'm running a type 4 dry pipe with 44mm carbs and my buddies build is the same except has 38's and it screams. More power all around than mine even sounds better. I've done all I can do.. I'm stuck now idk what else this ski wants from me. Something's jacked up... Yet it's all fresh. New crank seals new cases all sealed up well all new gaskets and head o rings and rebuilt carbs even throttle shafts and butterlies. Everything is rebuilt...

 

[bondra131]

Yea man shops are the same around here. Dirt bikes and sleds are popular here and idk how good dealer mechanics are with custom parts on those toys even... I'd never go to them for help. No I don't have a sled. Can't afford another sport and I ride my ski nearly year around anyways

dude I feel your pain, I see your from Idaho and i'm from Iowa. What I mean is NO one around here knows jack about the aftermarket world when it comes to pwc, especialy standups and blasters. Every time I go to the sport dealers and tell the guy behind the counter I own an HX and a Waveblaster he looks at me with dear in the head lights. I'm betting you own a sled though. I've had to teach myself about tuning as well. So take this for what its' worth. If you havn't read the Mikuni manual several times yet do so. Group K has good info as well. My recommendation and I don't mean to talk down to you but I would reinstall those 38's and then start tuning from idle to low speed circuit and mid range and then worry about main jet. Your not going to get much ridding in this way but this is how I would do it. This is slow and time consuming but well worth the knowledge you'll gain. Use that knowledge to know what it takes to use big carbs. The info for 38's is abundant. I too have an aftermarket intake but don't have the time to try bigger carbs. Make notes as to what works and what doesn't work. lol keep reading and have fun with it.

 

[bondra131]

2.5ns 115g springs and 112.5 pilot, either 115 or 120 main can't remember the mains... No I don't have a timing light but I have msd enhancer and the stator is definitely lined up slot to triangle where it should be for oem timing

Pop-off is about right, chart shows 19PSI
What jets are in them now? A good starting point is LS = 130, HS = 120. Start with LS-screw at 1turn and HS-screw at 1turn. Adjust screws individually and test to see if any changes to jetting are needed.
Have you checked the timing with a light to verify it is right?

 

[swapmeet]

So... Maybe I missed this, but..... What's the problem? Are you just mad because your buddy has more power with 38's so there fore it must be tuning?

Fiddling with it is a waste of time when there's so many combos that can be tried...

This statement reeks of someone who doesn't want to put in the time to learn.