Exhaust copper tubing as exhaust?

Discussion in '2-Stroke Engines' started by mechanicojoe, Jan 17, 2009.

  1. machiasmort

    machiasmort Active Member

    For the expansion chamber portion of the exaust, use a large diameter copper pipe available at any pipe vendor. Use reducers to get back to smaller dia. Fumes from copper are bad news!

  2. i was actually thinking about that today. doing that would never really be "right" by any means, the couplers would be no where near the taper you want for controlled gas expansion but if you went from 1" to a coupler to something like 2" and then down to 3/4" at the end you could probably get some decent performance out of it.
  3. fastboy9

    fastboy9 Member

    It would be nice, but the convergen and divergent cones have to be a very specific dimension, as every time the exhaust gases hit a rough patch i.e shear curve the pulses will change direction, ruining the whole effect. I think the best thing would be to do is take the actual expansion chamber section off from a small motorbike exhaust, maybe a kawasaki KX65 as that is pretty close to the cc of a happy time, or even from a pocket bike if moneys an issue. Then using copper pipe you can tune it in with various header lengths until your torque curve is just right :), thats what I did and another guy on here did, plus you dont have to weld it, silver solder should be ok, but I would braze it if you can.

  4. relaxxx

    relaxxx Member

    Solder definitely melts off. When my muffler broke off I soldered a 3/4" copper fitting on the end of the pipe where the muffler broke off. The fitting was threaded so I could screw on a homemade can muffler. It melted and fell of in minutes. I never tried brazing before but I suspect it would hold a lot better. What I did was cut a couple slits in the fitting and attached it with a hose clamp. If it ever falls off I think I'll look into brazing. It crossed my mind that I could maybe make an expansion chamber by using a few different sized plumbing fittings (3/4' to 1' to 3/4' ).
  5. back in the day when people were first tuning 2 stroke engines they found out that the longer they made the exhaust the better the engine ran because the more back pressure they got. so im sure if our engines can run at all with the crappy exhaust they come with then a super long 1" exhaust that tapered down to a super small fitting like a .7" or smaller about half way through the exhaust, you could get a decent exhaust reflection effect from that. from that. flow would definantly be good with just a straight copper system.
  6. I did a mix of chromed steel flange and bx conduit cable 1/2" in between (2) 3/4" copper couplings tying in to my exhaust with JB weld and the bonding agent and at the flange the JB and the copper took the heat of a 80cc 2stroke less than 2 " s away from the jug