Super Jet Stock exhaust, what's inside?

[Pro-pulsion]

Over the last few weeks or so, I have noticed a lot of either new take-offs or virtually new stock 701 exhaust systems. I was just wondering if anyone has ever dismantled the stock pipe to see if there is any possibility for modifications. I assume the end cap on the manifold is just to have a universal one mani fits all option, but what about that big chamber with the elbow on it? It looks like it can be disassembled too, what's in there? Can there be things done to it to make it more of a bottom end pipe?

 

[JetManiac]

Waste of time IMO, the whole design is terrible for performance.

 

[Matt_E]

It's a box that's designed to reduce noise and fit inside a hull.
There is one known performance improvement that has been found to be "worth it": Remove and replace with a real exhaust system.

 

[tor*p*do]

oem exhaust is not worthless,
you might be able to get a few cents for it as "mixed metal"
at you local scrap yard

 

[Pro-pulsion]

Oh I will definitely be putting on an aftermarket pipe. But I was just wondering if there has ever been anything done to the stockers to make them into something reasonably good. It certainly does look like a whole lot of unnecessary pipe parts for something that performs on a basic level at best. It seems odd that such an elaborate design carries such poor performance, plus with all the extra hardware it couldn't be cheaper to mass produce over a coupler design could it?

 

[Tyler Zane]

The weight savings alone...

 

[cattledog]

on the stock sxr pipes the smart and fast racers use some elaborate water routing and drying of the pipe t o make them work better

 

[Pro-pulsion]

on the stock sxr pipes the smart and fast racers use some elaborate water routing and drying of the pipe t o make them work better

I always liked doing mods to stock parts. I have had a lot of really good luck with modding stock parts and the best part is, you don't have to break the bank account to get great performance doing it that way.

 

[CarterB]

a beater crusty pipe of any sorts aftermarket will be heaps better than modified stock brick. lots of old raider, blaster, sn 650, and even some kawi stuff can work for you!

 

[js/sj]

The OEM exhaust is quiet, and is reliable. I have never broken one. If they came with bpipes everyone would complain of noise and the coupler would go bad after a while. Look at these SN sj's that are 20 years old and almost all if not all of them have zero exhaust issues.

Just sayin.

Sent from my DROID RAZR HD using Tapatalk 2

 

[JetManiac]

The OEM exhaust is quiet, and is reliable. I have never broken one. If they came with bpipes everyone would complain of noise and the coupler would go bad after a while. Look at these SN sj's that are 20 years old and almost all if not all of them have zero exhaust issues.

Just sayin.

Sent from my DROID RAZR HD using Tapatalk 2

And a canoe or kayak is super quiet and even more reliable, but not great for freestyle.

 

[Pro-pulsion]

I might get some heat for saying this but I just can't help but really like the Kawi 650/SuperJet cheater pipe set-up. I have had such a good reliability and performance experience from that set-up on my Kawi that it will be my main project for my SJ engine this Spring. After all the r&d I did with the Kawi pipe and finding the best bottom end length to make it, the size of the water injection ports and locations, it just seems logical to me that the SJ will respond very similarly with that pipe. I have heard and read on a lot of occasions that when done right it can be a very good pipe, and from my own experience I agree with it. It's too bad the stock 701 pipe couldn't be as promising but they do make good wall hanger displays :biggthumpup:

 

[bowman4u]

sj exhaust manifold

I might get some heat for saying this but I just can't help but really like the Kawi 650/SuperJet cheater pipe set-up. I have had such a good reliability and performance experience from that set-up on my Kawi that it will be my main project for my SJ engine this Spring. After all the r&d I did with the Kawi pipe and finding the best bottom end length to make it, the size of the water injection ports and locations, it just seems logical to me that the SJ will respond very similarly with that pipe. I have heard and read on a lot of occasions that when done right it can be a very good pipe, and from my own experience I agree with it. It's too bad the stock 701 pipe couldn't be as promising but they do make good wall hanger displays :biggthumpup:

If anyone is interested i have a coffman 701 exhaust manifold brand new never ran for sale if interested text me at 831-238-7938

 

[kevbo]

I might get some heat for saying this but I just can't help but really like the Kawi 650/SuperJet cheater pipe set-up. I have had such a good reliability and performance experience from that set-up on my Kawi that it will be my main project for my SJ engine this Spring. After all the r&d I did with the Kawi pipe and finding the best bottom end length to make it, the size of the water injection ports and locations, it just seems logical to me that the SJ will respond very similarly with that pipe. I have heard and read on a lot of occasions that when done right it can be a very good pipe, and from my own experience I agree with it. It's too bad the stock 701 pipe couldn't be as promising but they do make good wall hanger displays :biggthumpup:

Not really, the stock Kawasaki pipe has some tuning effect where the Superjet pipe has none. A stock superjet pipe may be better for hood tricks since there is no power surge. It makes linear power with less peak thrust compared to an aftermarket tined pipe. If all you need is 500 lbs of thrust then use a stock pipe, if you want over 600 then go aftermarket and deal with the surge by fanning the throttle.

 

[gto0209]

the stock pipe works better when its dryed out. Like others have said, they are not the highest performance, but they serve the purpose quite well.

 

[Matt_E]

the stock pipe works better when its dryed out. Like others have said, they are not the highest performance, but they serve the purpose quite well.

They're not only "not the highest performance", they are without a doubt the worst performance.

It muffles the exhaust well enough, but out of any PWC I have ever worked on, the stock 701 exhaust is the absolute worst. Well, maybe the stock Yamaha 500 is worse.
Other manufacturers managed to come up with designs that combined good performance with good sound dampening.

 

[Pro-pulsion]

^ lol Matt, that so far is the the most comical description of the stock 701 pipe. I must admit, I am actually somewhat shocked that these pipes are so widely despised. It just seems odd that nobody has tried to do anything to them to get some real power out them. I keep wondering that if a person were to find some materials that would fit the bill, could the expansion chamber not be lengthened and at least offer some real bottom end? It makes me laugh to think that in our world where everything can be modded, everyone hates the stock pipe of this ski so much they don't even want to spend the time to try and get something more out of it, talk about one of those all time blunder designs lol. It probably wouldn't even be a good anchor would it? What about filling it with foam, painting it neon orange and using it for a starting line buoy?

 

[Pro-pulsion]

If anyone is interested i have a coffman 701 exhaust manifold brand new never ran for sale if interested text me at 831-238-7938

I appreciate your intention here bowman even though this little hijack attempt should have been reserved for the parts for sale forum, I am curious to know how much. I might be interested, even though I have one already I have been considering one that is original and not bored out like mine is.

 

[Matt_E]

Here's the problem: a 2-stroke motor needs a tuned expansion chamber to get more power out of it. That's what the b-pipe is. That's what the PFP is. They all have similar shapes because that's what works. You want the exhaust pressure wave to hit at the end of the chamber, reflect back and stuff unburnt fuel back into the cylinder.
Kawasaki stock pipes do that.
Seadoo stock pipes do that.
Polaris stock pipes do that.
A lot of Yamaha stock pipes do that.

The 701 bread-box, on the other hand, does not. It's not a typical expansion chamber shape. It's just a box. It's like the engineers just went: "Well , we only have that much room. Fit this here box on there and call it good!"

They probably had a similar thought process when deciding on what impeller to put into it.

 

[Pro-pulsion]

:haha: "breadbox"! I never thought of it like that but it's true lol! I am certainly familiar with the tuned pipe concept and how the reverse cone is as equally important as the lead in tuning cone. As well I agree with 100% on stuffing the unburnt fuel charge back into the cylinder, that is done by way of sonic sine wave reflection due to the reverse cone and length of chamber determines the duration of the sine wave return time changing the power curve. I spent a lot of time researching that as I was considering making my own tuned pipe for my Kawi 650sx. I agree, there are certain times where going with the crowd should not be avoided. It's amazing they were able to claim in the service manual a total rated HP of 73 for that sort of exhaust tuning when my 650 Kawi was claimed to be 50 in the service manual. How did Yamaha manage to stuff the additional 23 horses into that short little breadbox?