$25 expansion chamber works great!

Discussion in 'Performance Mods' started by Hard rider, Nov 22, 2007.

  1. Hard rider

    Hard rider Guest

    Hi guys,
    I just installed a pocket bike pipe on my Dax 70cc with 44T, pipe itself costs only $25 can be found at
    http://cgi.ebay.com/Exhaust-Chrome-...ryZ11332QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
    The good things about this pipe are it cheap and easy to install. I started from welding 3 brackets on the pipe and then drilled the frame and use M4 bolts to hold it. Then cut the old exhaust and connect them with old radiator hose, the hose will melt while engine is hot but you can get it run for 20 mins with no problem. The only way to connect the pipe together is welding only, i have tried using exhaust repair kit which sold at autoshop but it didnt work.
    This pipe give alot of torque, i can hit top speed which around 31MPH alot faster ( around 25-35% more than moded stock pipe ) you will definately feel the gain. I can go up the hills in San Francisco with no problem and also at faster speed. It gives a very nice exhaust note, abit louder than stock pipe. But only thing that i didnt expect to see was it will not give you any more top speed. It will pull quite hard all the way up and go flat at 31MPH which the same top same as my moded stock pipe does.
    Overall, i love the pipe and it is worth $35 ($25 for the pipe and $10 for the brackets welding)
    Hope this help if you looking for something cheap and effective!
     

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  2. Hard rider

    Hard rider Guest

    Side and rear pics!
     

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  3. gone_fishin

    gone_fishin Guest

  4. Sianelle

    Sianelle Guest

    Does the pipe get in the way of your left leg?
     
  5. I agree with Sianelle....is it a little warm around the leg?....Looks nice tho!...I guess probably no faster overall because with stock gearing the engine is probably tached out anyway....maybe a smaller rear sprocket is in order?
     
  6. Ghost0

    Ghost0 Guest

    Nice job Hard rider, I am doing the same with a pocket bike pipe. Should turn out similar. You need to use silicone tubing and you won't have to weld anything. You can find it at most hi performance shops or hydraulic supply stores. It is typically blue or red and is fiber reinforced. It can handle the heat. Also if you want more top end, shorten the pipe. The shorter the distance from your cylinder to the expansion chamber the higher it will rev. The longer the distance the lower it will rev but will have more torque.
     
  7. Hard rider

    Hard rider Guest


    Thanks man! ive been looking for this kind of tube for a while. Can yo give me some more idea on hi performace shop, what kind of hi performance?
    Thanks
     
  8. Hard rider

    Hard rider Guest

    The widest part of the pipe might rub your leg just a abit , it is really not a big deal, give it for 1 mins and you will figure it out how to ride without touching the pipe.
     
  9. Ghost0

    Ghost0 Guest

    Any hi performance car shop should carry it but I would just look in the yellow pages for a hydraulic supply store and ask them for some hi-temp silicone tubing. You can also get it on line at http://www.stylinmotors.com/straights.html.
     
  10. Skyliner70cc

    Skyliner70cc Active Member

    Most online radio control model airplane vendors sell silicone tubing for tuned pipes.
     
  11. Ghost0

    Ghost0 Guest

    That is true but usually not in the 7/8" ID that we need. They are usually in the 1/2" range. Here is a pic of the tubing for some visual reference.
     

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  12. dave1490

    dave1490 Guest


    not a bad fit,follows the contures of the bike nicely.almost looks like a factory install.i,d paint that crome part of the old pipe black though.also the clamps.
     
    Last edited by a moderator: Nov 23, 2007
  13. Hard rider

    Hard rider Guest

    Thanks for your info Ghost!
     
  14. Thanks for the tips Hard Rider and Ghost.
    That set up looks good on the bike.
     
  15. Skyliner70cc

    Skyliner70cc Active Member

    Sorry, but your reply to my original post was not accurate. Here is one example of a model airplane vendor that sells 7/8 ID silicone tubing.

    http://www.aerotrend.com/shop_subcat.php?subcat=7

    Commercial model airplane engines come in many sizes larger than 70cc.

    Check out some of these beauties that range as large as 212CC 4 cylinder engines! http://cactusaviation.com/Products/Engines/Signature/signature.html
     
  16. Ghost0

    Ghost0 Guest

    Ya sorry for the misinformation. Although not that "old" myself I am still stuck in my modeling days when the largest motors in the R/C industry were like 21's and 40's. I know they have some 1/4 scale cars and plains that use some 100cc motors. Sorry for this off topic but check this motor out. Would make a cool bike motor I think.
    http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=5734
     
  17. What exhaust chamber works best on a twin cil.engine?

    Ghost that's a nice engine.
    Now imagine that engine on this bike: http://www.hawkclassic.com/#
    on the chainless driveshaft transmission Hawk ACE model like on a BMW bike.
    The question related to this thread is: Does anyone know what would be the ideal expansion chamber on a Twin Engine performance wise? Two separate ones or a common shared one like this one comes equiped with? (The stock one looks ugly, like a VW bus muffler).
    But that ACE bike and this engine would make a nice ilegal 100cc 10HP "BMW like" **** of a bicycle!
     
  18. hot70cc

    hot70cc Guest

    I agree, be sure to post pics of you burn marks on your leg in the summer time while riding with shorts on lol. I'm sure you will figure a way to avoid being burned, but it only takes a grazzze of the leg and your scarred. Not the setup for me thats for sure.
     
  19. You can also use silicone sheet as insulation on the pipe too, or fiberglass header tape, to protect your leg. They make oven dishes and mittens out of the stuff. Nice mod, surprised I haven't seen more bikes with a real expansion pipe on them, it makes a huge difference. I'd like to see it go under the bike though.
     
  20. kevbo

    kevbo Guest

    McMaster-Carr (see catalog page 230) sells silicone heater hose in a number of sizes (1/4" to 6" diameter)) by the foot. I've also purchased this (up to 2" ID) at Westfleet, which is sort of an auto parts store for big trucks and commercial vehicles.
     
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