"True" Dual exhaust on a chinese 80cc

[DuctTapedGoat]

So, can you extend an expansion chamber with for example, a poopoo pipe sans the actual exhaust? Would you still get the benefits of an expansion chamber with that much neck between the manifold and the actual chamber?

 

[ken murphy]

fab'n exhuast

The pipes are designed with a certain lenghth between the port and the cone
I have never seen 1 that has greater lenghth in this area a snail pipe has less. at the start of this I made a mistake suggesting the poo poo,if you want an expansion chamber buy the one they sell that goes up front then extend the pipes on the back end of it then you will get the benny.
kenny

 

[DuctTapedGoat]

Well, I was using the poopoo as just an example of length I want to extend the expansion chamber, but I know that there are certain mechanics to the expansion chamber, and it seems that it's a necessity to have it be a certain length from the manifold. As well, I've seen pictures of an expansion chamber on a poopoo styled extension. I know it can be done - but will it actually have the same effect and control over the band?

 

[ken murphy]

As for what I've done with these lil motors they never produce the same result,I've never had 2 run the same.ya just have to do it.If you do what you are say'n,it will make a change.I've made a dozen or so pipes,I'll have to take a picture of a couple I have made.(off the bike's)I'll tell you 1 thing you get two bikes run'n side by side down the canal with the pipes i've made and it sounds pretty cool,thet sing at 35-40 mph I've rode beside cars and used a gps to measure speed.Any little thing you do will change the motor.Back to the original question------yes you can add to back of the chamber you see all the time on up pipes,the manufactur's always put the silencer on the last,as I do.look up expansion chambers on E Bay,get some ideas in your mind and fab it up.
happy trails

 

[DuctTapedGoat]

... not really the answer I'm looking for.

If I put a Twinkie in my exhaust I'll get a "change". I know there's differences in motors and builds, but I know that if I get an HT motor I'm not going to hear Al Stewart coming out of the exhaust, I'm going to hear a 2 stroke.

I know I can add to the expansion chamber. I "can" do lots of things - but will the mechanics of the expansion chamber work with a longer distance between the manifold and the actual expansion chamber. What are the differences between the stock installation method and putting an extension on it? Do you have less or more control over the top end or low end of the power band? Is it useless with an extension or does it maybe run better?

 

[Dave C]

About all you ca do is cut and try. With all the different shapes avalible what works for one pipe won't work on another. You got those little banana pipes that hook right up to the exaust port, SBP's setup with adjustments right at the header pipe, and the King pipe that the expansion starts way away from the port. Being an old racer I like the SBP setup.

 

[HeadSmess]

I suggest you read up on how a tuned pipe works and what it does then you will understand why I provided the advice I did.

ahem. the stinger or end of a tuned pipe is as important as the pipe itself... the books say it right there.

the wrong end will affect them. designing a good 2 stroke SILENCER is actually harder than the pipe... go rip the muffler off of your old cr250, take it for a spin and tell me differently.

the same applies to the front of the pipe. that length, those angles, those tapers....all very very critical. i turn my nose up at whats available for these engines cus, while they will work, to a point....they arent real. theyre made more to "look" the part.... having a piece of silicone tubing with hose clamps is not how you design a tuned pipe. they bear a striking resemblance to the pipes you find on the 50cc ebay quads etc... pressed seam welded tin can...

(unless someone can give me the actual design specs with graphs n stuff of these pipes from the factory in china that originally manufactured them to shut me up and make me feel silly)

not throwing dirt on the idea of twin pipes though.

if you can handle the stock power... and can bend pipe would sorta look sick with good stainless turning pretty colours

but, now im thinking of it... what if you did run two tuned pipes? calculated with only half the port area each... i wonder.... and then even with two different tunes?

grrrrrr!! now i wanna experiment! these are things you cant find out about in books...

 

[Nitropeewee]

"2" pipe or not "2" pipe

I say expieriment. ive used pipes for 49 cc pocket bikes, stock, stock "modified"and curently have an expantion chamber off a yz 85 with the stock muff on the end. The yz pipe has been the best so far. Looks a lil weird like a big bladder er sumthin. I will also say every single pipe ive used, i have had to either richen or lean out the carb. Good luck n have fun!

 

[Lolokustoms]

I just ordered my expansion exhaust for mine,i should have it done in a couple weeks..i say experiment as well!