a good drill bit for porting muffler exhaust?

Discussion in 'Spare Parts & Tools' started by happyjourney, Feb 5, 2012.

  1. happyjourney

    happyjourney Member

    i'm looking to do this http://www.youtube.com/watch?v=iOtli8s0HZA&feature=related and wanted to know what a good drill bit to do that with would be. i'd think a normal metal cutting drill bit with the twisted groove pattern would bounce around and try to get caught up and try to wear away spots. i was looking at some drill bits that had ground up diamonds in the tip that was a rounded flattened end like you would see with a hobby kit. he's using a hobby kit type die drill. i only have a cordless 18volt dewalt drill so i was planning on using that but those bits i was looking at on harbor freight were on backorder right now.

  2. Al.Fisherman

    Al.Fisherman Active Member

  3. happyjourney

    happyjourney Member

    you are always a great help to me. thank you
  4. tooljunkie

    tooljunkie Member

    i use carbide burrs,quite expensive.
    i can use in a drill,turning very slow.
    they will eat through most metals,softer metals will plug up the burr.
    take your time,secure part in a vise or some sort of fixture,allowing you to operate tool with two hands.
    what the guy was doing in the video was pretty crude.gasket sealing area needs to be smooth to keep a good seal.you could do just as well with a round file and a little elbow grease.
  5. motorpsycho

    motorpsycho Active Member

    you don't want to use a drill bit for this. A drill bit is for making holes, not for removing material.
    you'll want to get a dremel tool because it will have to be high speed to be effective.
    I mean you could do it with a drill and a carbide bit, but most drills don't have the rpms that a dremel will have, and it will take a lot longer to remove that much material.
    you can get a cheap set of cutter bits (burrs) and sanding stones usually from wal mart...like $20.00 for a box full of them.
    altho these will not be carbide, they will get the job done, but they wil not last as long as carbide.
    but in reality....how much do you really expect to gain from doing this?
    it's not like you're going to gain 1/2 horsepower.
    If it were me, i'd just use the money that I would end up spending on a dremel and cutter bits, to buy an expansion chamber.
  6. Fabian

    Fabian Well-Known Member

    Been through this process of modifying stock mufflers and intake tube etc.
    At the end of the day it just makes more noise; irritating and painful noise not just for the user but for everyone else in the neighbourhood, providing only minimal increase in power.

    If you're going to make more noise and upset everyone with the infernal racket you might as well do something constructive and actually "increase power" with an expansion chamber and increase torque with a reed valve intake system.
    At least the reed valve intake will noticeably reduce intake noise, so maybe that's some small compensation for those who are sick to death of listening to your bike ripping up and down the street in the process of tuning your engine whilst simultaneously devaluing neighbourhood property prices as everyone wants to move out to a quiet and peaceful location.

  7. Neon

    Neon Member

    I personally won't port any engine with a carb on it. will stick to fuel injected only. The reason is that when it comes down to it. The carbs can be very difficult to jet properly after porting. Fuel injection can make those changes all by it's self up to a point. If it can't a computer flash can make things right again.

    As motorpsycho said a dremel or high speed rotary tool is the best thing to use for porting. They are small enough to allow better control. where a drill is rather large. You can very easily ruin a cylinder using a drill. Drills are fine for honing, but i wouldn't use one for porting. High speed rotary tools are not that expensive anymore. I managed to get one with 100 piece attachment set for $29.99 before taxes. Works just fine. A little shopping around and you can usually find as good of a deal. But you need to shop around.
  8. Fabian

    Fabian Well-Known Member

    If you are involved in the quest for serious horsepower whilst maintaining good reliability, the only serious option is a Morini engine; """designed to get the job done""" in more ways than one.

    Lets face facts and physics: travelling at 50+ miles an hour on a bicycle that was never designed to do more than 25, with glaring safety deficiencies at such high speeds is a sure fire way to land you in the emergency department on life support.

    If you still want to have a crack at it, this engine will get you there:


    At the end of the day, money spent trying to seriously improve China Girl engines is simply throwing money down the sink hole, but at least the power of a standard engine is proportional to the capabilities of a well designed bicycle; given that it's ridden sensibly.
  9. StrontiumEthics

    StrontiumEthics Motored Bikes Sponsor

    Actually the carbide bits aren't THAT expensive. I found site that sells them quite cheap. This is where I get mine from and they are pretty awesome! Apparently Dentists use these tungsten carbide bits as well!

  10. darwin

    darwin Well-Known Member

    HF has a cheap dremel tool with choices of bits that works for awhile, its not a dremel.