New Pipe Build

Discussion in 'High Performance Bicycle Engine Tips and Motorized' started by Davezilla, May 8, 2014.

  1. Davezilla

    Davezilla New Member

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    Ok, I knew it was going to happen eventually, just didn't expect it to happen earlier today but my modified pocketbike pipe broke off at the lower mounting tab. I was going to just weld the tab back on and carry on with breaking in my newly built engine but once I saw just how thin the metal was and that it was even thinner where it broke off, I opted to go ahead and build up my new pipe. This one started life as a 2013 KTM 50 pipe and I got it off ebay last month for $30 because it had a nice dent in the belly section, luckily that's in a non critical area but I hammered out most of it while I had the pipe cut in half.

    Here it is tacked together, I had to cut it at the middle of the belly and re clock the baffle cone as well as rearranging the bends at the header inlet area...
    [​IMG]

    And here are a few more pics of it after it was welded up and installed...

    [​IMG]

    [​IMG]

    Last pic just shows the layback seat post I made yesterday, I actually made it about a week ago but took it back off and welded in a gusset brace because I could feel it flexing while riding earlier so I had to fix it before it got worse...
    [​IMG]

    I was able to start it up just long enough to hear it and it sounds much more like a dirtbike than it did before, even with the old expansion chamber. It also revs a lot faster and has a nice agressive sounding idle... Here it is with just the header from the old pipe, I made it a slip fit at the header so when the bracket broke the header stayed put and intact.... https://www.youtube.com/watch?v=SstiA9_qYs4
     
  2. allen standley

    allen standley Well-Known Member

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    Niiiice! That bike means BUSSINESS. sounds tuff as h_ll.
     
  3. Theon

    Theon New Member

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    I was looking at my other KTM pipe today for the Goat, It's very similar to how yours started life, I like what you've done.
    I was seeing mine go over the top of the motor, but couldn't figure it out to anything I was happy with.
    Will stick to my 'torque pipe for now.
    But the KTM would suit it better.
    Motor sounds spot on.
     
  4. sub66

    sub66 New Member

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    great purchase and thread but engine needs reeds for the noobs out there planning the ktm pipe stuff doesnt it? i just never heard of a p.p. with a circuit exhaust before is all.

    does the motor bolt up ok? anyway you might not like the circuit pipe on a piston port. how is it? do you like it?
    fantastic initiative from texas again.
     
  5. Davezilla

    Davezilla New Member

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    Actually I was saving this pipe for my case inducted project, but since my pocketbike pipe broke and the metal was really thin and in bad shape where it broke I went ahead and cut it up and re welded it so it would fit this one, the engine will be in the same position on this bike so it'll fit the new engine when it's done anyway.

    For how it works on this engine, I'll soon find out, about all I was able to do with it installed so far was just a quick startup in the garage at about 2am, it's a lot quieter than the video I posted but still pretty loud, and it filled the garage with smoke in no time flat... lol. It did rev smoother and quicker with this pipe tho and still has that agressive note to it.

    This bike has a small frame and not a lot of room so mounting the engine took a lot of re thinking since I really didn't like the way it was before with really long M6 bolts on the front mount to get around the frame, I cut slots in the frame and used a 1/8" thick mild steel strap thru the frame to bolt the engine onto, it works and looks way better but I really need to weld it in place. I'll have to tack weld it then take the engine out to finish the welds but after it's welded in it won't go anywhere.
     
  6. sub66

    sub66 New Member

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    i have to keep the rear mount angled correct or it just moves. anyway it sounds lean is what i was gonna say. give more backpressure to help w the lean low end maybe.
     
  7. sub66

    sub66 New Member

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    ogh well probly not done.
    but smart or lucky i think it will be good for ur 66cc the way it is now. it just might not slow down lol. it really looks ok minus the muff/ stinger. im surprised to see it unfinished a little.
     
  8. mech_engineer

    mech_engineer New Member

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    looks good!!! any video of the sound?
     
  9. Ron344

    Ron344 Member

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    i really like the look of your pipe, Let us know how preforms. I have one I made on one of my board track bikes and it sounds great.
     
  10. Davezilla

    Davezilla New Member

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    No vid for sound yet but I'll update later today or tomorrow... It definitely sounds different than it does in the last video I posted as it took on a really cool dirt bike sound when reved out, and the idle still sounds very agressive.
    Been waiting on my new carb to get here today but now I'm out of time so I'll have to install it when I get home from running a few errands... If the carb is here when I get home I'll install it and tune it out then shoot another video, if not I'll at least fire it up and shoot a vid for everyone to hear...
     

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