SX/SXi/SXi Pro 1100 triple in my sxi advice

Chris03HD

Chris03HD

Location
Jersey Shore
The modified 900 chamber, to bolt up to the 1100 head pipe and exhaust manifold, is a big space saver IMO.

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kwakhead

kwakhead

Location
macomb
well, heres the materials you need. buy it all from us composites.com, Epoxy Resin half gallon and medium hardener, mixing container, mixing sticks, 5 disposable brushes, fiberglass CLOTH 11 oz to 20oz. do like 3 layers.
will cost around $100 for all the materials, but its easy once u get to it!
1 cut a hole out the correct size to make the perfect amount of space for your exhaust
2 LEAVE your exhaust over the hole you cut out in the hull, and just put saran wrap aropund it so the fiberglass doesnt stick to the pipe, you need to have the pipe bolted on like usual so u can fiberglass around it.
3 sand the area with 60 grit real thoroghly and clean it with like carb spray or something.
4 then mix up ur resin and cut out 4 layers of fiberglass cloth, 1st layer is smallest in size, then u get bigger around as you add on layers. look up videos on fiberglassing before you do any glassing and learn how to do it. its not hard, just requires paitience. look up this thread, 550sx hull modernization build, he shows his whole fiberglassing process as he builds, you will get a good iudea from that. then just go on youtube. but dont buy home depot resin, its polyester resin and it wont stick. you want epoxy resin from uscomposites.com and 10oz of fiberglass. id say like 1 yard of it.
 
theVetteman3

theVetteman3

Location
Chicago
I admire your enthusiasm on this lol. Engineer right?

Based just on seeing the pics on my phone, if you mill the exhaust manifold flange this ramp problem will be less because the ports move horizontal. They may travel down some but it won't be as critical as on the cylinder side.. Which I for sure as heck wouldn't modify either.

I'm not saying this is perfect but with some careful grinding and polishing with a foredom you should be able to do a pretty good job. Adding material by welding then grinding is also an option to raise up the bottom edge. I have a friend who saved a super cylinder which was ported too much by doing this, so its possible.

But Yea by no means should you mill and leave it at that! Flow is so critical like you said cowboy. Even the surface finish is critical, let alone having a mismatch.

Nuclear Cowboy said:
Also, DO NOT mill the exhaust ports on the cylinders!!!!! NOOOOO NO NO
@heynagel I hope you haven't pulled the trigger on doing that yet... I do NOT recommend doing that at all... milling back on the port ramps, like I said, will have a TERRIBLE effect on volumetric efficiency. Think about the amount of turbulence it creates when you put a shelf right there for the exhaust gasses to jump over while decreasing the diameter that it can flow through. And more importantly, think about WHERE that turbulence will occur.... IMEDIATELY upon exit of the cylinder. A 2-stroke engine would be crippled by this. It would still run, but it will NOT be just a small loss of power, it would be dramatic. You'd literally be better off leaving the 750 in there.
Here's why....
By introducing turbulence to the exhaust flow immediately, you interrupt the sonic pressure wave that a 2-stroke depends on. That sonic wave is what creates the vacuum pulling the exhaust gasses from the cylinder. If the exhaust gas encounters immediate turbulence, the sonic wave will be disturbed and broken apart as soon as it hits the sharp edge of that "shelf" (for the same reason sharp angles are used in sound-proof surfaces; they break up coherent sonic waves. and vice-versa, why a tuba in a marching band is shaped with the same smooth flowing curves as a 2-stroke pipe, to amplify a coherent sonic wave).
If you disturb that wave immediately after it is created, you essentially render the expansion chamber useless. The whole concept of an expansion chamber is based on that coherent sound wave traveling through it. It is designed to expand and amplify the wave (think tuba) before reducing the volume of the chamber down to normal pipe diameter. This amplifies the wave and then causes it to bottle-neck and resonate backwards towards the cylinder until it impacts a much more dense volume of gas (the fuel-air mixture) coming into the cylinder at the same time the exhaust gasses are leaving. When this backwards-moving wave impacts the dense cloud of fuel, it essentially "pushes" it back into the cylinder to ensure that the maximum volume of fuel remains in the chamber as the piston closes over the exhaust port to begin compression. ALL OF THIS IS LOST IF THE SONIC WAVE IS LOST!!!

That means you might as well just lose the expansion chamber completely and just run normal tubing out of the manifold because it wont even have an effect anymore. And of course by doing that, you have a much quicker and easier solution for how to fit the pipe into the engine compartment anyway!! lol
bottom line is... DO NOT mill your exhaust ports!!!
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Sxi 1100

Sxi 1100

Location
Winter Park, FL
I have a modded lower 1100 chamber when I ran that setup in my sxi. No milling no glass work required. The threads are stripped so helicoils are needed. Pm if interested
 
701TFH

701TFH

Location
California
Sxi 1100 said:
i installed an 1100 on my sxi. it doesnt have the space as an sxr. the factory engine plate will bolt up, you will also have to have the drive shaft from an stx shortened by 2", modify the factory 1100 expansion chamber, as well as the inlet tube on the water box, cut the baffling out around the exhaust for clearence and relocate the ebox. its alot of work but do able. i will post pics of mine soon if that will help give you an idea
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Doing the same conversion, what did you do to the exhaust chamber and drive shaft to make the 1100 fit pics would be awesome thanks! Your build looks clean!
 
Sxi 1100

Sxi 1100

Location
Winter Park, FL
701TFH said:
Doing the same conversion, what did you do to the exhaust chamber and drive shaft to make the 1100 fit pics would be awesome thanks! Your build looks clean!
Click to expand...

It's been so long. I know I shortened and welded my drive shaft, the stock expansion chamber was shorten as well as narrowed from the exterior side. You can use the factory aluminum water box but you will need to cut it open. Put a couple more holes in the baffle and cut off the inlet pipe and get a pipe to match the same size as the 1100 chamber outlet. I'll have to look on my old computer to see if I have detailed pics


Sent from my iPhone using Tapatalk
 
Sxi 1100

Sxi 1100

Location
Winter Park, FL
Sxi 1100 said:
It's been so long. I know I shortened and welded my drive shaft, the stock expansion chamber was shorten as well as narrowed from the exterior side. You can use the factory aluminum water box but you will need to cut it open. Put a couple more holes in the baffle and cut off the inlet pipe and get a pipe to match the same size as the 1100 chamber outlet. I'll have to look on my old computer to see if I have detailed pics


Sent from my iPhone using Tapatalk
Click to expand...

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701TFH

701TFH

Location
California
Sxi 1100 said:
It's been so long. I know I shortened and welded my drive shaft, the stock expansion chamber was shorten as well as narrowed from the exterior side. You can use the factory aluminum water box but you will need to cut it open. Put a couple more holes in the baffle and cut off the inlet pipe and get a pipe to match the same size as the 1100 chamber outlet. I'll have to look on my old computer to see if I have detailed pics


Sent from my iPhone using Tapatalk
Click to expand...

Awesome thanks! Any info on the pipe and drive shaft would be awesome!
 
B

Bryson Olson

Location
Truckee, California
No way!!! Yes!! So this shaft was used for a 750 SX/SXI to 900/1100 conversion? Will you measure it make sure it's 22 inches or less with the coupler on. How can I PayPal you some money to get it? Call or text me at 530-845-0989 so we can set up shipping and payment. You're a life saver!
 
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