760 swap runs amazing, but the throttle is idle or rip your arms off.

Location
cali
How can you come to that conclusion over the internet?
I will say everything I have read said the bottom screw is the one I should have been messing with and not the top, yet it made it worse. Enough so I took it all apart and made sure the ports were free flowing and all equally functional, so I do think Wax is on to something.
 

E350

Site Supporter
Location
Sacramento Delta
It is very difficult to cruise slow with big carbs and a good pipe. It will tend to be on or off. If you want it really smooth then install a set of OEM 38mm carbs and a stock Superjet pipe. You will lose some max pull and speed but the throttle will be very linear.

@allted Have you considered that your ski may actually be functioning as it is designed as modified?

I briefly rode @wavewarrior's piped Super Jet and it was like that. Idle or Hyperspeed and nothing in the middle. That is how it was supposed to be. He said I would get used to it, and I am getting parts together to put a pipe on the FX-1, however, my guess is that I would prefer a more linear increase in power so it will be an interesting experiment.
 
In my experience with reading, you find that the majority doesn't really take the time to properly tume their own ski. They copy someone else's combo that works decent enough to ride and they leave it. I've got 2 buddies with the same exact hull, both ported 735s dual 38s, mod chamber bpipe, zeeltronc ect. One has a oem 155 pump, the other a 144 mag. They handle and ride completely different and have different carb tunes. The 144 mag ski is real peppy off idle and revs super quick, the 155 pulls harder but doesn't sound as revvy because of how the pump loads the engine.
 
I'm not trying to be rude or anything I'm just curious how wax says that the tune is off because the top screw is open. My engine builder gave me a setup log on how to set the carbs up and where to set the screws he recommended the top open 1/2 turn and middle 1/4 turn. My buddy with the identical engine with the 38s headpipe is tuned identical. Both run excellent.
 

E350

Site Supporter
Location
Sacramento Delta
@DylanS and others this could be a very informative thread, because inexperienced riders like me hear about "pipes" all the time but I really don't have much experience with them (except for our 650 X2 which has a pipe and a single Mikuni 44BN and has a very linear throttle) so don't know what to expect from a pipe. I don't even know what the goal of having a pipe is. Is it for getting instantaneous max-power to send the ski into a flip? Is it to pull out of a tight turn? I am really clueless about the problem that a pipe is supposed to cure.
 
Location
cali
I suppose it could be. Like I said I appreciate the power and I am comfortable and can ride it great. I just feel like something is not right, or as good as it could be. I have ridden all sorts of two stokes and never felt anything like this. If this is how these things are, I am okay with it. If there is something I can do I am capable and comfortable with all levels of motor building and tuning. I have learned it is best to ask before diving in when I know some of you have way more experience than I do.
 
There's only one way to learn and that is to quit being lazy and take some time to dial your ski in. Try different things and see what works best. You'll find that every little thing different will result in being tuned slightly different.
 

DylanS

Gorilla Smasher
Site Supporter
Location
Lebanon Pa
@DylanS and others this could be a very informative thread, because inexperienced riders like me hear about "pipes" all the time but I really don't have much experience with them (except for our 650 X2 which has a pipe and a single Mikuni 44BN and has a very linear throttle) so don't know what to expect from a pipe. I don't even know what the goal of having a pipe is. Is it for getting instantaneous max-power to send the ski into a flip? Is it to pull out of a tight turn? I am really clueless about the problem that a pipe is supposed to cure.
A well tuned 2 stroke pipe produces a supercharging effect at a desired RMP range that can be felt by the rider and increases horsepower (sometimes drastically). You’re two stroke motor is a big Ol air pump. The more air and fuel you can cram into it the more arm yanking power you can get out of it. Basically a well tuned pipe uses the pressure wave from the exhaust gasses to suck extra fresh air and fuel through your intake hence the “supercharging” affect. I won’t write a book on this fellas post but I highly suggest you read up on the concept, its fascinating.
Anyways lots of guys like to setup their motors/pumps/etc to have that “hit” that’s being more or less described in this post. That snap is a awesome feeling.
There is a very cool thread on here somewhere that explains why your kawi cyls roll into the power instead of having that snappy response (hence why you almost never see kawi motors in freestyle skis).
Most of it has to do with the ports/port roof angles.

Every motor will behave different depending on every little detail, the trick is to figure out what works best for your specific setup to optimized it and figure out if you enjoy what you came out with.
 
And adding water to the pipe changes the entire game on a 2 stroke. Adding water into the chamber will slow that return wave basically fooling the engine that the pipe length is longer but also lower the upper rpm power. Adding water to the stinger will increase the back pressure and increase power up top. Similar to changing the stinger diameter. And kawasaki engines not having the bottom snap is mainly because of the higher exhaust port timing. They can be setup to be super torquey and snappy it just takes more compression and timing to get there which affects reliability and longevity. Lots of timing and compression does all kinds of things to the crank haha. Also how the pump is setup is equally important. Something not often talked about.
 
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Location
cali
There's only one way to learn and that is to quit being lazy and take some time to dial your ski in.
That comes off a bit harsh. I ride several times a week as work permits....and far from lazy.

That snap is a awesome feeling.
OMG is it ever. I have not stopped talking about it with my ski buddies since I first rode it. The only issue is I feel like I am missing some finesse you get from having more linearity. I am fine with a dirt bike reed kick, just sold my 2000 cr250 to pay for this ski, this is far above that. Fun either way, if this is how these parts work together I will either change them or just keep riding the snot out of it.

Wax seems to be implying it is not tuned as well as it could be. It came fresh from a local tuner before I bought it, but I have zero confidence they are perfect. I will go through the steps and see if some jets change much.
 
Location
dfw
You probably wont like overly rich pilots if you are smoother with throttle inputs. Most riders fan the throttle 30 times a second which will make 1/4-1/2 throttle range feel leaner than it is if you hold it steady. The bottom screw is for idle only and the main jet/top screw is for full throttle only. Everything in between is pilot jet and popoff pressure, this area will vary depending on how you ride. These engines are easy to burn up at full throttle so make sure to tune the top screw rich of peak rpm.
 
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Location
cali
Is that why everyone is constantly blipping the throttle, to smooth out the punch when they don't want it?! I always thought they were trying to dump more gas in to get a bigger punch or something. Coming from dirtbikes, blipping is not the thing to do. It is all about throttle control so that is how I have always ridden the skis.
Everything in between is pilot jet and popoff pressure
Makes sense.

So much info today. Maybe I can pull a half day and go ride at lunch tomorrow to see if I can run the SBN tests and get a better understanding of this.
 

waxhead

wannabe backflipper
Location
gold coast
How can you come to that conclusion over the internet? I guess my tune is off on my ski as well cause my bottom screw is closed and I'm not reverse jetted. Yet everyone that gets on my ski all say how dialed it is. Help me understand.
I have tuned a few skis over the years, this helps somewhat I guess.
You can make a ski run really smoothly and seem awesome with the top jet on the pipe open and everyone will think its awesome, Then when they get on a proper reversed jet ski with the pipe set up correctly it will change their perspective. What is being dialed ?? smooth from the bottom to the top ??? that just means is carbureting well, I have ridden a lot of skis that carburate well but it does not mean they are making as much power as they could. We bought an hyandi i20n Awesome little pocket rocket and one of the most fun cars to drive I have driven. You can flick a button on the steering wheel to go between Karen ( economy) mode and power. Both modes the car is dialed. power mode has a heap more punch and midrange. The top end hp is the same 1655354095152.png
 

waxhead

wannabe backflipper
Location
gold coast
Is that why everyone is constantly blipping the throttle, to smooth out the punch when they don't want it?! I always thought they were trying to dump more gas in to get a bigger punch or something. Coming from dirtbikes, blipping is not the thing to do. It is all about throttle control so that is how I have always ridden the skis.

Makes sense.

So much info today. Maybe I can pull a half day and go ride at lunch tomorrow to see if I can run the SBN tests and get a better understanding of this.
You are also keeping the pipe temp up as well.
 

waxhead

wannabe backflipper
Location
gold coast
No I have not done the exact tests. I absolutely will now though. Need this wind to calm down a bit, 15mph plus gusts makes things a bit variable.

Some days I go pretty far out to get a burger, so I do try the throttle for long times at all positions. I was looking for hesitations at various positions, Check the plugs, exhaust temps.

At the 1/8th mark I can hold it super steady and try to creep up to it and everything is fine, then it just jumps and goes. Beyond that it is fine as well throttle response everywhere, it just jumps from like 15 to 25 at that one spot. I need to put some marks on the throttle to have a look. Everything is pointing to 1/4 being a crossover point, I was pretty sure it was before that but might be 1/4.
The jump is probably hitting the power band. this is what a pipe does to the ski
 

waxhead

wannabe backflipper
Location
gold coast
I'm not trying to be rude or anything I'm just curious how wax says that the tune is off because the top screw is open. My engine builder gave me a setup log on how to set the carbs up and where to set the screws he recommended the top open 1/2 turn and middle 1/4 turn. My buddy with the identical engine with the 38s headpipe is tuned identical. Both run excellent.
Try tuning the pipe as I said and get back to us. Are you restricting the water going into the stinger ?? if not put a 4mm restrictor in there. Make sure that you are teeing putting most water overboard from the top fitting of the head pipe and then the T is headed down to the stinger with the 4mm restrictor as mentioned before
 

DylanS

Gorilla Smasher
Site Supporter
Location
Lebanon Pa
.OMG is it ever. I have not stopped talking about it.
Wait until you ride a 900cc plus dialed in machine.. will change your world :)
Years ago I was meh with skis until I rode a DVX with a almost perfectly dialed in 927. Came back to shore with shaking arms and have never been the same since lol
Honestly if the ski doesn’t feel like it’s trying to kill you as soon as you bump the throttle then you aren’t living..
 
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