new exhaust WOW!!!

C

captainrichhill

New Member
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.
 
Venice, was just checking out your web site. Pretty work fo'sho! PantherIII is a work of art. Any problems with the fenders on the Nirve bikes? I am getting this Nirve.com - Men's Cruiser Bikes and really want to keep the fenders and live. lol
 
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mechanickid said:
how do i start a new thread?
Click to expand...

Once you have picked the forum you would like to post in....

Up on the upper left you will see a sprocket that looks just like the "reply" sprocket.

Except this one will say "New Thread"...click on that and enter the title of your thread and type away and then hit "submit" at the bottom.

Need any more help let me know :)
 
I took some pics of the new exhaust. I can't seem to post them. First it asked for the URL. I have them on my computer. Then I tried to attach the pics and it said that the files were to big and I don't know how to resize them.
Any pointers??
 
captainrichhill said:
I took some pics of the new exhaust. I can't seem to post them. First it asked for the URL. I have them on my computer. Then I tried to attach the pics and it said that the files were to big and I don't know how to resize them.
Any pointers??
Click to expand...

I'll send you a private message with my email; send them there I'll resize them
 
Re: new exhaust WOW!!! HERE are Captain Rich's PICS

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

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captainrichhill said:
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.
Click to expand...

That's a nice lookin' muffler and pipe.... I think I gotta try to make one. Nice work....
 
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 :)
 
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.
 
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.
 
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
 
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......
 
MyPC8MyBrain said:
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 :)
Click to expand...

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
 
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