questions concerning exhaust collector

[hipshot]

externally, there are 4 inlet ports, and 2 exhaust ports.

internally, there are also 4 "tubes" on the inlet ports and 2 tubes on the exhaust ports.my question is ,would removing or shortening the "internal tubes" , have any serious effect on the overall engine performance?

referring mostly to carbs.

just jt

[hipshot]

70 lookers and not one reply!

even a bad reply would convince me that "someone" actually read this post!

just jt

[painterman67]

I did read the post I jusat dont have an answer.....my mechanical skills are growing daily as I read these threrads. it why I keep paying the anual dues. But I have no idea as to what the answer is . And yes I was one of the 70 or so who opened it originally.

 

 

David

[a1bummer]

I kind of doubt it. I would think it would help the engine breath better. But not so much better that the carbs would need a lot of adjusting. But then I'm not an exhaust engineer either.

 

Bill

[Freebird]

I too had refrained from posting because I'm not 100% sure...but now that you have PUSHED it I'm going to say NO, it will not have a negative effect. I think it is Mark's Pipes that makes the SS collector and I don't think it has any ports like that.

[friesman]

I looked too but i dont know anything so I thought i would leave the answering to someone that had a correct answer for ya....

 

Brian

[twigg]

I too had refrained from posting because I'm not 100% sure...but now that you have PUSHED it I'm going to say NO, it will not have a negative effect. I think it is Mark's Pipes that makes the SS collector and I don't think it has any ports like that.

 

Do you have a link for that?

 

How much does he charge?

[Flyinfool]

I seem to remember some discussion on this topic on this site a long time ago.

I seem to remember that the 4 inlets are part of a tuned exhaust and that changing that tuned length will reduce torque, horsepower, or both, depending on what you change.

In many of the threads where people have installed aftermarket mufflers that reduced back pressure, they had to mess with the carbs.

 

This is all from memory and I do have CRS.

[Freebird]

I don't think he has a website any longer but his contact information is in our links page here:

 

http://www.venturerider.org/viewarticle.php?articleid=59

 

Here is a small picture but the only one I found. They used to run about $350.00 but I think somebody recently reported that they had gone up a bit.

[hipshot]

thank you one and all, for the responses.

my "plan", is to grind out the "spot" weld that holds these internals in place.

raise them about 1/2 inch, so that they will serve as a "mating post". in this manner, i hope to get all of the new ports installed correctly.

otherwise, it'll just be a crap shoot.

just jt

[dingy]

I can see almost straight through my collector. I don't think that it is the source of the restriction in the exhaust system..

 

The stock mufflers are another story. They are very nice quiet units. If you want some performance, these can be modified by removing the end caps, and first set or two of baffles. I left the very first baffle in mine.

 

They are not real loud, not near what a straight set of HD's sound like, but they are different.

 

As far as a number to put on the HP gain, I don't know, this is only one of several changes I have made to power train, so I can't pin down a specific item.

 

I still have a set of unmodified mufflers, and they don't seem to hurt performance. But then, I have only used them a couple of times when wife was going on longer ride with me, so I can't judge it under those conditions.

 

Gary

[Squeeze]

Generally speaking, shortening the Lenght of Exhaust System causes the Torque and hp Curves to shift upwards in Relation to the RpM. That goes for the Intake System also. Most likely you'll see a slight Increase in the Values, but that goes along with a change in low and Midrange Power, which is not the Target of most our Riders here. Because is causes a little Lack of get-up where we ride most of the Time.

 

That said, it may be different on the 1Gens. That's because the when you cut out some Corners, the Collector will have better Flow and by this allowing to make up the lost Values. It's a matter of trying it for yourself.

 

The Ride will change, yes, but for better or worse in your Purpose is rather unkown.

[twigg]

It's also worth noting that these engines are in a very low state of tune.

 

They are 1300cc motors tuned to deliver less than 100bhp. It's not inconceivable that they could be made to deliver anything up to about four times that amount of power, although they might not last long.

 

Modest power gains of 30 to 40 bhp would be easy but here is the thing .... You cannot change just one thing without a knock on effect. Even changing the air filter for a free-flowing type affects the carburation, and changing the exhaust affects it more.

 

It's likely that opening up the exhaust leans out the mid range and wide open throttle conditions ... by how much is not known until you do it. Be prepared, if you fit a K&N Filter and remove baffles, to raise the needles a notch, and/or increase the main jet size.

 

And you might get away with none of these changes. You won't know until you try. What I am saying is that simply fitting a free flowing exhaust, because it looks great or sounds nice is noy always a straightforward proceedure (and sometimes it is). A dyno session with a decent technician can work wonders.