new exhaust WOW!!!

Motoschwinn · #11 (**permalink**) 09-25-2008, 07:38 PM

OK here is what he made. I took the liberty of just posting them for him. They are huge files, here are three.

Nomad · #12 (**permalink**) 09-25-2008, 09:53 PM

Quote:

Originally Posted by captainrichhill

I just build a new exhaust for my 70cc HT. I started with 3/4" metal electrical conduit then went to 1". I cut wedges out of the pipe where I wanted to bend the pipe. then I welded it all back together. I added a pocketbike muffler ($20 delivered) and it sounds AWESOME!!!!! I get about 4-5 mph (on bike computer) more speed. The outlet for the muffler is back behind me and away from the back wheel (not getting on my back rim and on my rear brakes. Thats a good thing.
I hope someone else will benefit from my post because it reall was cheap and great for performance.

That's a nice lookin' muffler and pipe.... I think I gotta try to make one. Nice work....

Nomad · #13 (**permalink**) 09-25-2008, 09:57 PM

Nice clean looking engine, where did you get it... nice bike and build altogether.....

MyPC8MyBrain · #14 (**permalink**) 09-26-2008, 10:38 AM

Nice job on the pipe. That reinforces my thought about how the exhaust on these motors is the biggest thing holding them back.

I like the 1" pipe. I was going to build a prototype with 3/4" but now you have me rethinking that. Even without an expansion chamber... 20% gain. Awesome.

Rear exit mean no more 2stroke smelling shoes too ! I hate that

captainrichhill · #15 (**permalink**) 09-26-2008, 09:27 PM

The bike is an old Performance Hybrid (1/2 way between a road bike and a mountian bike) The engine is a "70cc" from Dax. It's been pretty good. I ordered it when Dax was behind and it took awhile. I've replaced the engine mounting studs along with the exhaust studs with "actual steel" 6mm studs. I added an upgraded ignition wire and NGK spark plug. Soddered and heatshrinked connections in the wireing. And now it's a new exhaust. The bike has been great and alot of fun. Then again I love tinkering in the garage. I would recommend this engine to anyone.

Dominate. · #16 (**permalink**) 10-11-2008, 04:20 PM

I'm a complete noob. Is that exhaust hard to make?

captainrichhill · #17 (**permalink**) 10-11-2008, 05:36 PM

The tubing was cheap. About $10 for 8 foot piece. (Home depot) Plenty of material for do overs. I took my time and tack welded as I went. I cut 2mm wedges out of the areas i wanted in the inside of the curves. If you have welded before you shouldn't have any problems.

Jemma Hawtrey · #18 (**permalink**) 10-11-2008, 08:47 PM

Interesting you get such a performance boost since it seems that you have managed to make a throughflow exhaust much as is done with the tuned 4-stroke headers on the large v-8s and such.

I do have to say it looks pretty good and very tidily done

Jemma xx

misteright1_99 · #19 (**permalink**) 10-11-2008, 11:39 PM

Looks like you have really cut back on the backpressure as jemma points out. You have to be careful, and keep and eye on your plug, becuase a 2 stroke without backpressure may run good for a while, but not long. Very nice job of fitting it to the frame, very clean......

okc_car_dude · #20 (**permalink**) 10-11-2008, 11:54 PM

Quote:

Originally Posted by MyPC8MyBrain

Nice job on the pipe. That reinforces my thought about how the exhaust on these motors is the biggest thing holding them back.

I like the 1" pipe. I was going to build a prototype with 3/4" but now you have me rethinking that. Even without an expansion chamber... 20% gain. Awesome.

Rear exit mean no more 2stroke smelling shoes too ! I hate that

Or just get front pegs, like me... to rest those feet on when the engine's goin' ;-) I got mine for 7 bucks on ebay, shipped. around here, you can also pick them up at walmart for 8.86 + tax, or something like that. keep in mind cost of living in Oklahoma City is among the lowest in the nation, though. :-P