Vibration solution?

Discussion in 'Frame Mounted Engines' started by darwin, Jun 23, 2008.

  1. darwin

    darwin Well-Known Member

    Ive noticed in alot of pics with the frame mounted engines that the engine is only supported at the base. It seems everyone has a vibration problemo with these...........anyway I was thinking if a mount going to one of the head bolts would help to dampen some of the vibes, nothing fancy just a flat bar with 2 holes in it or something.
     

  2. datz510

    datz510 Member

    The vibration is due to the piston throwing itself around inside the engine, so the more solidly the motor is mounted, the more vibrations you're gonna feel.

    ideally, you'd want rubber motor mounts. I'm still looking for a good solution for mine.

    The vibrations are pretty annoying after 20 miles or so.. My hands start going numb from the buzzing.
     
  3. fastboy9

    fastboy9 Member

  4. pedalpower

    pedalpower Member

    vibration solution

    okay, I'm a newbie, I've never even been on a MB, nor experience the vibration everyone is describing. But I'm brainstorming-mmm, dangerous.

    This is what I have on my road bike, they go into the handbar ends:

    http://revolutioncycles.com/itemdetails.cfm?id=2788

    Anyways, I followed the thread about attaching a 3rd mount to the cylinder head but to me that just seems futile, like that is going to keep it from shaking.

    I don't even have my engine yet and haven't even figured out which bike I'm gonna use but now I'm thinking about a solution to the vibration. In a word: cancel.

    Perhaps by extending the mass of the cylinder head by attaching something to the cylinder head bolts we can in effect create a harmonic balancer, so instead of transferring the vibration to the rest of the bike and person, it can be reduced at the source?

    considerations: is the vibration a necessary inherent feature of the 2 stroke HT (ntjl) for a happy well running engine.


    design?: maybe a square piece of wood (with a hole in the center for the plug) mounted (maybe an inch or so above) to the head with 4 pieces of aluminum that are attached to the head bolts.

    who knows what forces may be present in doing this but anchoring a head bolt only seems a good idea to those who sell replacement head cylinders.
    jon
     
  5. I totally agree I would not want to place and more strain on the head bolts and studs than the strain they are under from compression.
     
  6. Fabian

    Fabian Well-Known Member


    A single cylinder engine cannot be balanced, by nature of it's mechanical design, unless a balance shaft is used, which adds weight and complexity; going against the very ethos of the bare to the bones simplicity of a low cost 2-stroke engine.
     
  7. jaguar

    jaguar Well-Known Member

    god, you people are like doctors, fighting the end problem instead of rectifying the cause. Just replace the heavy wrist pin with a lighter one. If thats not enough then remove metal from the cylinder head to increase compression which also helps. if thats not enough then drill holes in the piston in places that won't cross the intake or exhaust ports. and no, it won't make the piston shatter due to structural inadequacy. I drilled 27 holes in one of my pistons and rev'd all the way up to 8500 rpm and used it for months without any problem. try it and then report back here so others will see that it works. see my anti-vibration info on my site by clicking on my signature link
     
  8. Purple Haze

    Purple Haze Active Member

    Here's another idea: Has anyone tried to externally balance one of these engines? That used to be the low-cost method the Detroit factories used when they made long stroke smallblock engines. They added an imbalance at the flywheel or harmonic balancer to counter the imbalance on the crank throws. Also, Fabian has a point about single cylinder engines being impossible to balance, but they can be balanced at a set rpm, which will work if you run at a certain steady speed most of the time. For most of us, Jaguar's method will work best, but requires a lot of trial and error testing. Another thing, instead of drilling the piston, the same result can be had by removing material from the end of the rod, especially the parting line which is quite pronounced.
     
  9. Ludwig II

    Ludwig II Member

    There's always the MZ solution, which is to mount the back of the engine on a bracket pivoted on the frame, and place a rubber mount on to something solid from the other end. You don't cure the vibration, you just watch it from the safety of the insulated mounting.
     
  10. jaguar

    jaguar Well-Known Member

    Purple Haze, I tried to drill a hold in the upper part of the connecting rod but man o' man is that metal hard! I gave up. It probably could be done in a machine shop though once its off the bike. But I think for most people going that far won't be necessary if they first try my suggestions.
     
  11. jefuchs

    jefuchs Member

    Isn't this one of the claims about boost bottles?

    http://www.gasbike.net/boost-bottle-kit-66cc.html

     
  12. jaguar

    jaguar Well-Known Member

    a totally unproven claim. I tested a boost bottle and it had zero effect on vibration.
     
  13. Ludwig II

    Ludwig II Member

    I think that if boost chambers worked, the manufacturers of modern 2 strokes would fit them as standard. None do. This tells me that people with an R & D budget have decided they're only a sales gimmick.
     
  14. jaguar

    jaguar Well-Known Member

    i think a 2 stroke trials bike would do good with one. But for most bikes there is no need for them.
     
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