View Full Version : 2 stroke pipe help

04-11-2007, 11:22 PM

Hey, ive got a question about the pipe for this 340 snowmobile motor that im putting in a trike. Its kinda hard to see but the manifold(yellow circle) on the motor points to the right and that is connected to a small connecting pipe thing(red circle) and that connects to the expansion chamber thing(blue circle). Hopefully this isn't too confusing.

I havent really been able to find a position to put the pipe in that works very well with the trike, but I can make it work if I just conect the expansion chamber directly to the manifold and dont use the connecting pipe thing. Will this drastically (sp?) change how the motor runs? I dont want to change how the pipe and motor function together.

04-11-2007, 11:32 PM
Thats a Kohler motor, right?..........or is my radar getting bad?
Looking at the muffler itself, could you turn the inlet pipe basically 180*, and then the muffler would sit inside the frame in front of the engine, underneath the manifold?
The exhaust system is a tuned system, but kinda crude.......
You could definitely get away with not using that junction pipe, and the engine would run about the same.
We did it on older sleds all the time, with no issues. I wouldn't worry about it.

04-11-2007, 11:39 PM
yup your good, 340 kohler from a 79 JD spitfire. I was actually thinking about the exact same thing your explaining today too. It doesnt quite fit below the manifold, but theres room for it above the manifold. The gas tank looks like its sitting low because i didnt have the front mounts welded on when i took the pic. If i put it above the manifold or managed to squeeze it below, would i have to worry about the heat from it raising the engine temp or wouldnt that be an issue?

04-12-2007, 12:02 AM
You're not gonna want to mount it in front of the cylinders. You want the air going across the fins as cool as possible.
The old free-air sleds were frequently timebombs in warmer weather......I've owned a few. The El'Tigres were famous for meltdowns......especially the 500's.
I'm not real sure about the Kohlers, other than that they usually run real nice.
Is it possible to carefully dent the muffler and have it fit below? Maybe cut those unused brackets off?
You're gonna need all the air to the engine you can get to help keep it cool.
I'm gonna eyeball it........maybe something will come into my head;)

04-12-2007, 12:04 AM
hey now that i think about it, your idea might work even better than i was thinking... when i tried to fit it below the manifold i planned on bending the junction pipe into a 180 and using that to connect them. Your idea seems much better and cleaner, just hack off the pipe's inlet and turn it a 180*. lol now why didnt i think of that...

04-12-2007, 12:11 AM
I was thinkin the same thing about the heat infront of the cylinders. warm weather+a pipe right infront of them wouldnt be a good thing. right now im really liking your idea to put it right below the manifold. I'll probably try to fabricate some big aluminum or galvanized shrouds to direct more air to the fins. Hey on a side note, you think it would be a good idea to mix the oil a little richer or go up a size on the main jet to help ther heat?

04-12-2007, 12:17 AM
The only other thing I can think of offhand right now would involve welding, and stuff........
That's the same basic manifold that was on my 440 F/C Kohler in the Skiroule I used to have.
There is no easy way of modifying it without some fabbing, because of how it's made.
It's basically 2 90* bends, one being longer that meet at the ball connection.
I was just thinking....if you made the manifold into a Y that faces forward, and slightly down.............
Then you take the muffler, and cut the connection pipe right off.
Cut the straight part with the connector off, and weld it to the muffler so it sticks straight out.
Turn the muffler so it's straight up and down, and put it in the frame that way.
Just angle the bottom of the muffler in some. That's where that slight down angle would come in. the muffler would sit in front of the engine like this....//
Then your exhaust outlet would come out the bottom of the frame, and you could angle it or whatever, maybe.
Just another thought I had.............
I might still have some stuff floating around here from some of my old sleds, also.

04-12-2007, 12:25 AM
hey i see what you mean, that would probably be about the best setup. For now, I think im gonna try to keep the fabrication to a minimum and probably go with your first idea of putting it in the frame below the manifold but i may very likely change it later once i get the trike finished up.

btw, i really appreciate your help and thanks to you i've got some good ideas on how to make it work.

04-12-2007, 12:33 AM
No problem..........I would do a plug check for jetting.
It's gonna be one of those things............
You're going leaner by not using the airbox, but you'll be richer because the air is warmer, less dense. It's kind of a toss-up.
I would do a plug check, and go more for the brown side than tan. As far as oil, 32:1 should be okay with decent oil.
Gotta see the finished product when you're all done:D
Should be pretty cool.


200x Basket
04-12-2007, 01:24 AM
i would get a 250r drag pipe and mount it up. forget that stocker

04-12-2007, 03:02 AM
i would get a 250r drag pipe and mount it up. forget that stocker

I agree. I would try some banshee pipes...That thing you have in your picture belongs on a John deere...lol

04-12-2007, 03:33 AM
What is this for drag if so maybe run the pipes under the motor or wrap it around the cylinder and out the back.

04-12-2007, 06:33 PM
I thought about a 250r drag pipe or sumthin but for now im gonna try to keep it simple and keep the price down a little bit. i might look for a drag pipe later on down the road. Its gonna be mostly for drag racin but im not really looking to be super competitive right now, the main goal is to get it running and driving and i'll worry about performance later.
For now, im gonna just stick the big pipe to the header and it will stick out the right side of the trike. Up until about 15 minutes ago, i was gonna put the pipe below the manifold in the frame but i just got done lookin at it and there just isnt enough room to fit it between the motor and down tubes, even if i cut those brackets.

04-13-2007, 08:50 PM
I got a husqavarna pipe that was retro fitted onto an atc 250r it made wicked mid and top pay for shipping you can have it! shouldnt be more than 25-20 dollars, let me know mayn

04-13-2007, 10:52 PM
hey syko, i think im gonna say no for now to the husqavarna pipe but thanks for the offer. I just came inside from getting the stock pipe on and im pretty satisfied with how it fit on and everything. I didnt have to do anything other than build a bracket to hold it and weld on 2 new ears for the springs to hook to. The pipe sticks out the right side angleing up and back and it connects directly to the manifold so im not using the junction pipe anymore. Thanks for your help guys.

04-15-2007, 07:58 PM
ya relly why the crap did they make the pipe that way. if you mesaure the tuned lenght then try to find a aftermarket pipe that is close to the same. atleast that way you could cut and weld it to fit if needed.