How do I weld motor mount?

Discussion in 'Painting, Welding, Bending and Gas Tanks' started by m3h5l5, Jul 28, 2014.

  1. m3h5l5

    m3h5l5 New Member

    Hey guys, I'm about to build my first 6.5hp bike. I just wanted to know how to go about welding on the bike tube, what power setting and such. I have a 90amp flux core welder, will it be able to weld the mount plate? thanks

  2. sparky

    sparky Active Member

    What type of metal is the frame made out of? What type of metal is the mount made out of?

    Ideally, you would know the thickness of the tube, and even have a spare tube of the same metal, thickness in order to practice with before actually doing your final run.
  3. butre

    butre Well-Known Member

    as long as both your frame and the mount are steel, it's all dependent on your skill level.
  4. gator joe

    gator joe Member

    What both those h iy told u was right on point .let me ask u this though.I ex's there a reason u need to weld a mount...that is a risky and dangerous proposition as far as alignment and getting good penetration and definitely if you do attempt itget something to practice on firstbut I don't recommend ittotally unnecessary
  5. Timbone

    Timbone Active Member

    I would be hesitant to WELD the motor mount onto the thin bike tubing. I would suggest you fab up a custom motormount for the front and rear out of very thick steel that you can attach to the frame via double U-bolts of up to 3/8" steel. You can find thick angle iron and weld your pieces together for both the downtube and the seat tube.

    Having a welder is a HUGE advantage. Good luck to you!

  6. fattirejack

    fattirejack Member

    I welded my motor mounts on the beast, and an pleased with the results. I have very minimum vibration, the motor is rock solid, and no worries about mounts shifting. Bike frames are made from very thin tubing, and can be different alloys. Your welder should be fine, settings would depend on thickness of your mount material. I welded my 1/4" plate to frame at a setting of 18 amps, but my welder is a high dollar 200 amp welder. If you are using a HF WELDER or similar you may need to set your welder at max to get penetration on your mounts, and take a chance of blowing holes in your frame. PRACTICE ON SCRAP MATERIAL, save yourself frustration, and possibly ruining your frame.
    Timbone likes this.
  7. I welded my motor mounts on my motorized bike. the best advice I can give you is do this process with a partner. basically do a mock-up of the rear tire, drive gear, motor and chain, loop the chain over both gears and have a buddy hold the engine to ensure the chain is tight and straight. make sure you tack weld first then double check for chain alignment. if it all looks straight finish your beer and weld it all the way. I use a flux core wirefeed 110v welder.
  8. RumblingV8

    RumblingV8 Member

    I did a decent weld job on my previous bike's motor mount. It's difficult. I didn't realize prior to welding quite how thin my particular bike's frame was and blew a hole in it in the first 1/4" of a pass at the lowest setting... was a little more careful after that and it turned out solid in the end. Next owner messed with the front motor mount and ended up breaking off the mount, probably due to a combination of stress from the changed angle and increased vibration. I elected not to weld the mount on my current bike because the motor fit in the frame properly. I don't think i would weld on a mount again after seeing how solid the U clamp brackets are, I'd rather just fab up a plate for that style mount.
  9. I know this is a year late but i have a bike build and im in the planning stage i dont expect to be able to do anything untill next riding season but anyways so here it is it would be this bike


    With this motor

    So my ideal because im pretty sure this is going to require some fabrication for motor mounts and such i dont have a welder at home but my dad does at his work. so honestly i dont know where to begin on this build i know the mounting methods are much different then our little 66cc engines but i know it can be done ive seen videos on youtube of same engine but on smaller bike then one that i picked out.

    The other thing is does anyone know if the lifan 125cc engine can be jackshafted to rear derailleur or might that be too much ideal i was thinking 11 speed moped with this ideal 4 internal 7 external i just want to know if it can be done maybe i fab a homemade heavy-duty derailleur to handle the torque of the engine would this ideal even be worth the thought the ideal behind this was to keep the rear disk brakes or ive heard of an adapter the supposed to work with disk brakes but does that still apply with a 4 inch fat tire bike also from what ive read about Jackshaft kits is its not so much for top speed its more for keeping the engine in the proper rpm range "sweet spot" as well as it helps for the dependability and reliability of the engine

    I also plan on adding


    Comes with everything headlight high/low, tail lights/running lights, brake, and both front and rear turn signals also includes a 100 decibel horn that can be heard 200 feet away includes battery

    So honest feedback from all like i said im going for costom motoped and do plan on registering with the state and get platted and insurance.
  10. Frankenstein

    Frankenstein Well-Known Member

    Too f***ing cool! Now I'm wondering... I've been looking at various 4 strokes and been thinking about what I could put in a schwinn Stingray, biggest possible that is.. Only think about a jackshafting this motor is its got a 4 speed transmission which also appears to be a manual shift. That means you'd have a 28 speed transmission, not 11,as you multiply the gears not add them up.

    Then the only other thing I could mention is that that much horsepower on a chain designed for a 7 speed cassette would be taking one hell of a beating, along with the rest of the bicycle's drivetrain.

    Perhaps you could look into a direct drive system, or an internal hub gear system like a cvt hub from nuvinci. However most gear systems will have issues with anything that's pumping out almost or beyond 11hp...

    Cool bike btw, what's it called?
  11. FurryOnTheInside

    FurryOnTheInside Well-Known Member

    There's no power running through the return side of the chain where the rear derailleur operates. Therefore I *expect* that even on MBs the failings of the derailleur systems are down to improper installation and maintenance, ie choosing cheap derailleurs (check the reviews on the ebike/MTB/etc forums), "chain suck" from worn chain and/or sprockets (you should expect to replace them very frequently), and overenthusiastic operation of the throttle. Impossible to prove that, though. I am going to try anyway (with a 66).
    But one thing is certain, a narrow ie multi speed chain concentrates wear. Halve the chain's internal width and you halve it's lifetime. This may be acceptable for a relatively pathetic 66cc but maybe not with a 125cc that outputs a lot more than double the HP.
    Is my thinking.

    Is a dingle acceptable? Two single speed ratios, using the same total tooth count (for the same chain length) on two different lines, both lined up correctly, but you have to stop, release chain tension and move the chain manually between the high speed sprockets and the town/hills sprockets. It is (not popular but known) from fixie cycling.
    I have been looking at it for the 66 but the sprocket cover /clutch lever mount dimensions cause real issues and limit the possible ratios and would require significant modifications. This may not be such a problem with the engine you're looking at. idk how the output sprocket looks on those but I think it would be worth checking out.
  12. Frankenstein

    Frankenstein Well-Known Member

    Actually his kit has an internal 4 speed transmission, I wouldn't even bother jackshafting it with that, it's almost like the single speed of a 2 smoke but you have the ability to shift at will, the 4 stroke kits for bikes don't even have a manual clutch or transmission, you have to let the machine do it for you.

    The reason I suggested the nuvinci is the hub is a single speed gear, you could put a pretty thick gear on it too and with some very heavy single speed chains too, that virtually eliminates chain problems. (I use a nuvinci hub, and kmc half link chains, they are tough nuts too, of all my issues I had I never had chain problems after upgraded to it, been using the same chains for 8 months now with very minimal stretch or wear to either the chain or sprockets. The only thing that went bad was my left side jackshaft sprocket, the big one, it got eaten up.)
  13. FurryOnTheInside

    FurryOnTheInside Well-Known Member

    Totally agree, four speeds is probably fine, four times seven is unnecessary and expensive. I only mentioned the dingle system as an idea that needs no jackshaft or quite so narrow chain, BUT now I think it could never have a big enough difference in the ratios to matter when the engine already has four gears that have a decent range of ratios. The new speeds would just be in between the old ones.
    I can't really comment on nuvinci hibs, but I have read about differing experiences. I don't like that it is a disaster if I does break down away from home.
    So what are you using for the left hand JS chain? How often do you check length and replace the chain? Is the sprocket the steel SBP one or the alloy?
    Last edited: Aug 11, 2016
  14. Frankenstein

    Frankenstein Well-Known Member

    It's also a 4 stroke, the powerband is nicely spread across most of the rpm range, that means, unlike a 2 smoke, that for the most part you'll be getting good power on the gears, and the powerband can overlap them rather nicely, I guess at that point you just gear the rear wheel for a modest mix of speed and climbing ability at the high and low end gearing.
    FurryOnTheInside likes this.
  15. Frankenstein

    Frankenstein Well-Known Member

    I also think that battery and light system is pretty cool too, I might end up ripping my setup off and putting that fancy one in, it's just the battery maintenance that I hate... Course with my set up I usually pull the battery in my bike, put it on the charger and put the charged one in, it's super easy but I want it to be easier.
    Jeffrey gagnon likes this.
  16. They sell the same kit with a 2 stroke charging system but its more expensive
  17. So the other thing i take from this is that the jackshaft would be useless. If thats the case where can i find a 4 stroke Jackshaft mounting braket


    Essentially it's basically just going to be used to support the bottom of the engine and this mount would be mounted to frame like its ment to be and then weld it on there
  18. FurryOnTheInside

    FurryOnTheInside Well-Known Member

    No idea what would fit with that engine and frame or why you would need the jackshaft mount if a jackshaft isn't to be used, but Sick Bike Parts do sell most of their shift kit parts as separate items for the custom builders.
  19. So to kinda get a rough ideal hear this is kind of my plan
    Red is mounting plate preferably the jackshaft one.
    Blue is where i plan on welding the mounting plate in position this being after i mount with steel hardware and weld it all together.
    There is blue on top bar and top of engine where they use a bolt or something of that nature i plan on making some kind of welded mount that can just be unbolted
    The yellow dots is the bolt hole pattern for the bottom
    And green is the engine in hopefully somewhat of a good fit without having to cut parts of the frame.
    I am also thinking of getting some of those side bars that go with the knee guard things on the harleys not the same thing something of similuar nature would weld some mounts on top and bottom of both sides of bike then fabe some bars to reach from top to bottom to give the bike more reinforcement as well to add a cage for engine just in case and with making a bracket to weld to the frame and bolt up easy to take apart if i ever had to remove engine

    So tell me what you think so far of my plans any and all advice is welcomed
  20. Frankenstein

    Frankenstein Well-Known Member

    It's a manual foot clutch, and kickstart, being that high up to the seat could make operating it difficult, maybe spring for the automatic version?...