Cheap expansion chamber

[DAMIEN1307]

Did you look through the muffler? Being that the muffler is smaller it will add some, just not the same as if the whole stinger was smaller, I'm talking diameter though.

It looks like a bloated sickle...lol...lol.

 

[Jayraye39]

Hey Jayraye39, I absolutely love your bike! I'm asking this question out of ignorance and curiousity. Why no reed valve?

Dont have the room for a good reed. So i just kept blowing it off. But now after i aggressivly ramped my piston. I think i might have just a hair more transfer duration thats optimal. The performance is their. Just getting a little more carb throwup than i like to have on my frame. Thinking about a small bolt on port reed. Ive seen 2 diff ones but not sure if any of the 2 are beneficial in my case. Anybody else know if the port reeds are any good?

 

[Jayraye39]

Pics of the Inside of my motor. Port work, piston crown, transfer duration, and plug color visible. Yes the cylinder is worn good but thats normal for the cheap plating and ring snags. The cylinder has been run hard going on 16 months now, I even melted a piston in that sucker at one point due to a gasket leak, need new one.

 

[Jayraye39]

Here's the issue I see with that pipe, the stinger from the divergent cone should go all the way through the silencer, one piece. If you can stick the outlet tip of the silencer inside the stinger, then the stinger is too fat. The OD of your header pipe where it goes into the first convergent cone should be like 25mm and the OD of the stinger pipe should be around 19mm. I bet the header and the stinger are both 22mm.

Yes , I replaced my stinger on this pipe with a hair smaller i. D. With 11in length. Much better than stock stinger

 

[Wevil Knievel]

Has anyone figured out the dynamics of the length to inter diameter ratio to exhaust pipe? Example: 80cc power band 2 foot @1inch for better lowend, 2'.8" × 1 inch for better mid ect...

I hate the off the head mufflers and was trying to devise an easy way to be able to put the stock muffler somewhere near the back tire preferably in a down pointed position for obvious reasons.

Im thinking a length of the stuff they use for these flex pipes with flanges on both ends so that you can attach one to the motor and one to the stock Muffler with regular bolts and maybe some little Buckle or something that you place over the flange that attaches to the muffler to hold them together when you bolt it down.

I guess I could just measure out the length of the flex pipe and add the length of the stock Muffler pipe (minus the "expansion/muffler") into the equation and cut it down to an a similar flow dynamic and tune it in from there.
Of course some compensation will have to be made for the lack of expansion chamber in line and mess with the stock stinger hmmm... but ya!
Damn... you guys are smart!!!

 

[Chainlube]

On a 66cc the header pipe, from flange to first convergent cone, has better performance in the 300mm range. Your overall expansion chamber system will have better performance if the measurement from piston face to midway of the divergent cone is in the 700mm range.

 

[Wevil Knievel]

On a 66cc the header pipe, from flange to first convergent cone, has better performance in the 300mm range. Your overall expansion chamber system will have better performance if the measurement from piston face to midway of the divergent cone is in the 700mm range.

You rock big dog