is this normal?

Discussion in 'General Questions' started by mickal1025, Jun 19, 2007.

  1. mickal1025

    mickal1025 Guest

    I recently took an old Trek and instauled an 80cc kings motor on it with puncher resistant tires and extra thick inner tubes, I have 1 tank of gas though it but it still has very bad vibration. its not bad until about 19-20 mph but after riding to work 1 way (9 miles) it leaves my hands tingling for 10 minutes afterward. I really want to use this or another motor kit but it has to be reliable. do I have a bearing problem on my new motor or do I just have the wrong motor. is it likely its not broke in yet? will it smooth out? idealy I would like to be able to ride at 30mph with little vibration. thanks

  2. bamabikeguy

    bamabikeguy Active Member

    Hi Mickal

    Keep in mind, when you use old bikes, especially with old spokes, a large portion of vibration comes up though misaligned wheels.

    Most of the happiest bikers switched right away to 12 gauge on the rear, 16-18 zip ties at the spoke junctions keep the spokes truer/longer.
  3. bamabikeguy

    bamabikeguy Active Member

    And I LOVE foam grips, a little elec tape on the ends keeps them from ripping.

    Use women's hair spray to hold them tight to the metal....
  4. Guest

    Guest Guest

    These frame mount engines smooth considerably with eash passing mile of operation. Mine finally got relatively smooth after 400-500 miles.

    Check the balance of your wheels as well, you have a lot of rubber rolling there.
  5. mickal1025

    mickal1025 Guest

    thanks guys. I have hope again. the vibration in this case is motor related because when riding down a steep hill I can pull in the clutch and let it idle down and it will go faster (30mph) with much less vibration. are there any newer bikes that that work well with the china kits? say a mt bike with front shocks or full suspention? just trying to equal, if possible, the ride of my Trek crossover peddle bike. I will likely wiat until i am sure this motor works out before buying anything else (new bike) but it cant hurt to mine for information in the mean time. thanks again, this is a great site, wish i had looked here earlier.
  6. Engine vibrations

    these engines vary, and, sadly, some of them shake like a wet dog, Mike
  7. mickal1025

    mickal1025 Guest

    if it comes to that. will better bearings help or are the connecting rod, crank, piston and other moving parts so out of balance that its a lost cause? I will put a few more tanks of gas though it and see if it improves.
  8. beast775

    beast775 Guest


    put inner tube on your frame where your motor mounts are!!!!!!
  9. Guest

    Guest Guest

    Do not put anything in between the engine and frame except for maybe a wrap of friction tape....using the "rubber mount technique" allows engine movement, which causes more vibration that "normal".
  10. mickal1025

    mickal1025 Guest

    tried something simular already. I used a rubber (1/8-3/16 thick) adaptor from a plumbing pipe then slightly radiused the motor mount clamp ends so the clamp would not tend to cut the rubber. still shakes like a wet dog as Mike so aptly put it. have heard of rubber isolation blocks at Farm & Fleet but have not gone to look yet.
  11. srdavo

    srdavo Active Member

    I almost always wrap my frames with a bit of innertube during an install. especially the fuel tank.....the friction from the rubber holds the tank upright, without stressing the tank mounting bolts by tightening too much.

    no rubber on the tensioner!! use good bolts & tighten the poop out of it!! :D
  12. mickal1025

    mickal1025 Guest

    ya I tried black tape too. I think that if I use the existing clamps mounted solid to 2 pipes 8" long or so then put the rubber dampers at the ends of the pipes, I think I would gain enough leverage that the motor wouldnt torque to the side and would still dampen the vibration. still thinking it over and am thinking about incorperating a chain tensioner into the mount also. I realy would like to lose that idler that came with the bike.
  13. FatPete

    FatPete Guest

    These engines need miles on the bores before they smooth out, Do what I did, lend you bike to the girl nextdoor and when she arrives home without a big smile on her face it's run in. She's on the bus and your bike's now nice and smooth.
  14. FatPete

    FatPete Guest

    motorcycle shops sell bar end weights, these fit inside the end of the bars and help to dampen out the vibrations. P.s. the girl nextdoor and I are still good friends.
  15. mickal1025

    mickal1025 Guest

    bar end weights. that makes sense. they sometimes use lead shot in boring bars to dampen harmonic vibration but I would have never thought of it unless you had mentioned it. thanks and that girl next door is still your friend because she wants to break in your next overhaul. a pipe filled with lead shot fastened to the motor might dampen vibration to if it was done right. where is a machanical engineer when you need one?
  16. Patch

    Patch Guest

    Harley engines are usually mounted on springs and with my newly found hobby (MIG welding) Im gonna try mounting my engine on shocks or sumthing, but you must be careful to not allow any motion other than a parabolic vertical movement.

    This save the chain and drive from getting chunky and messed up :D

    Chances are, it'll just vibrate right through the shocks to the frame. But hey what are boring days for anyways :grin: !
  17. mickal1025

    mickal1025 Guest

    a new intake gasket and getting some floaties out of the float bowl have made a world of difference I also think the motor may be starting to break in. the vibration is down to about 20% of what it was before. I still have vibration over 20mph but its very tolerable now.