Exhaust exhaust mount stud broken.

Discussion in '2-Stroke Engines' started by tskrem, Dec 18, 2009.

  1. tskrem

    tskrem Member

    yeah my exhaust bolt thingy snaped. how can i remove the rest? and where can i buy another?

  2. If there is some of the bolt sticking out you can try and grip it with some large pliers or locking pliers. if it broke flush and none sticking out, you will need a bolt extractor and drill. you can either order one online or look for it at a auto parts store or large hardware store.

    then you will need to order another set of bolts,either online where engine kits are sold or at a large harware store and bring a bolt with you.
  3. Al.Fisherman

    Al.Fisherman Active Member

    Can't add much to above except a little heat might help if some is exposed.
    As far as broken studs there are a few things I would recommend. If using stock studs that came with the engine...replace them as they are too soft. You can either buy partial sets or complete sets from any number of the vendors here, and I make and ship them.
    This is MY feeling... there are reasons why studs break..too much torque applied and/or the engine was not aligned properly. I never torque head studs (8mm) more then 200 inch pounds, when first being built 150-175. And the 6mm studs more then 50 inch pounds. Now this brings us to another situation. When using 50 inch pounds the engine tends to rotate left due to torque. I have solved this problem by putting a "L" bracket between the engine clutch housing and the bike frame along with double nuts, one being a self locking nut. In 5 builds, using 4 engines I have never broke a stud. I have over 500 miles on my bike and my son has about 400 miles. I ride mine like I stole it.
    Last edited: Dec 19, 2009
  4. If you put the muffler strap on and it hold the engine to the frame the engine wont tilt when tightening the bolts. i use a small adjustable wrench to tighten the nuts on the mounts until the lock washers are compressed,not no more than that. then i add a second nut after that and the second one hold the first nut on tight(double nutting).

    also if you have a oversize frame use a large oversize frame mount for the front or your studs will break.
    Last edited: Dec 19, 2009
  5. Al.Fisherman

    Al.Fisherman Active Member

    Front mount. Don't want to attach muffler rigid to the frame, you can break a mount stud that way...especially a exhaust.. The "L" bracket is cheap.

    Attached Files:

    Last edited: Dec 19, 2009
  6. Nothing broke they way i did it,but i am using the oversize mount on the front and have no studs on the front,im using the short bolts with heads.my muffler is mounted tight to my frame using the flex metal strap.
  7. motorpsycho

    motorpsycho Active Member

    what does head studs, and frame mount studs have to do with his exhaust stud breaking off?
    sounds to me like he just overtighened the exhaust mounting nuts.
    That's one thing i notice a lot...people over tighten things, which usually ends up breaking the stud. another thing is that a lot of people are limited on tools and they may use the wrong tool for the job i.e. an adjustable wrench, channel locks, vise grips or pliers.
    I know that a lot of people here are not mechanics and they do not have access to a full tool box of tools, and they use whatever they have on hand to do the job.

    on the exhaust, the nuts do not have to be more than snug...they use lock washers for a reason, and they do their job. once the gasket gets hot, it will swell, and actually make the nuts tighter just by it swelling up.
    just like an oil filter on a car, there is no reason to ever use a filter wrench to tighten an oil filter. hand tight will be fine because the rubber gasket will swell once it's hot and it will make the filter tighter.

    I don't mean to sound negative (if i do...i'm sorry for that) but i just wanted to point out some things that i "see" happening.
    even tho the china motors do come with cheap, soft studs, they won't break if you don't overtighten them.
  8. tskrem

    tskrem Member

    yes. i had taken my exhaust off when my cousins came over to show off the tourqe (compared to their little 23cc friction drive) and my dad told me to put it back on coz it was to loud. i told my cousin that ill do it when it cools down. but he wanted to keep riding so HE put it on, on the incorrect position aswell because it hit the pedals... so as i went on losening it, it fell off.. im still usure how to get it off because theres not alot to grip onto with my longnose or other pliers...
  9. Mountainman

    Mountainman Active Member

    sometimes a price to pay ?? showing off carries

    sometimes a price to pay ?? showing off carries

    easy out tap can be bought at Home Depot or Sears

    best not to let others work on our things
    if they don't know how -- to be done right

    ride that thing
  10. motorpsycho

    motorpsycho Active Member

    let me see if i am understanding this correctly. did the stud break where the exhaust attaches to the cylinder? or did a different mounting stud break off?
    A picture of what broke could help so we can see exactly what you will need to do.
    if the stud broke off in the cylinder, and it is not flush you will need to grind the stud down so it is flush with the exhaust mounting surface. then, you will have to center punch the stud (it is critical that you get the punch mark dead center on the stud). then you will have to drill the stud out being careful not to drill too deep and to drill perfectly straight. a slight angle on the drill bit cousl cause you to srill into the exhaust port.
    you can drill it out by starting with a really small drill bit and work your way up to a bit that is the same size as the stud. then you will have to re-tap (thread) the hole, and thread in a new stud. or you can drill the stud out and use a stud extractor to remove it. a stud extractor screws into the hole that you drill in the stud, but it is left hand thread. when you thread the extractor into the drilled out hole (turning it to the left to tighten it) you will be loosening the stud and the extractor will pull it out (hopefully)
    drilling out a stud in the cylinder is not easy and the best way to do it would be to remove the motor from the bike, and use a drill press to ensure that the drill bit goes in straight as you drill. IF this is the stud that broke, you have a lot of work ahead of you to fix it right without damaging the cylinder or the exhaust port.
    good luck.
    Last edited: Dec 21, 2009
  11. Al.Fisherman

    Al.Fisherman Active Member

    If you decide to drill it out, I'd use a left handed drill bit as the last one. Also I made a jig just for this procedure, to be used in a drill press. Although it is for a HT.
    Last edited: Dec 22, 2009