Minimize vibrations with home made bracket

Discussion in 'Frame Mounted Engines' started by fastboy9, Mar 27, 2008.

  1. fastboy9

    fastboy9 Member

    I found this idea on another site. Never seen it before its got a good installation guide.

    This is a third bracket that can be used to minimize vibrations from the engine by stabilizing the engine. This could be hand made using a strip of metal bent using hand tools and maybe a vice. One end is secured to the engine using the head bolt on the cylinder head. Then clamped to the top tube of the bicycle underneath the fuel tank.

    Just an idea to stabilize things a bit.

    Attached Files:

    Thejoed likes this.

  2. eltatertoto

    eltatertoto Guest

    pretty neat!!!, i might try that!
    Last edited by a moderator: Sep 17, 2008
  3. Demosthenese

    Demosthenese Guest

    cool. neat idea. nice and simple, probably quite effective.
  4. reclaimer

    reclaimer Guest

    I remember someone here, mentioning pocket bike motors have that third mount. That we should make something similar. Very cool to see it in the wild.

    Definitely going to find some new head bolts (6MM threaded stock right?), before attempting this mod. Would be better for the engine if we could get more than one bolt on the bracket.

    edit: a quick search told me 6mm threaded stock is right.
    Last edited by a moderator: Mar 27, 2008
  5. I want to make a note that a seperate nut is holding that bracket. There's a nut below that that keeps torque on the head.
    I like it. Gives a reason to replace the head bolts anyway.
    I do find myself about once a week or two holding my 10mm wrench retightening my motor mounts. I bet that mount would make my tightening a bit less frequent. Heck,I may even want to go smaller sprocket with the less vibrations.
    Last edited by a moderator: Mar 29, 2008
  6. fetor56

    fetor56 Guest

    Very good could be improved slightly by making-up a brachet and connecting to both head bolts,but what the guys done there is great.
    I'm gonna liberate this idea. :)
  7. Yes. Stronger too. I would go with a bracket that connects all four bolts except the spark plug may get in the way....or two brackets that connect the two front then the two rears.
  8. reclaimer

    reclaimer Guest

    I've been looking at the roadster today with this in mind. I think it can be done with 1 bracket to all 4 bolts but it wont be pretty. It's going to get one, but it may take awhile to find something that pleases my eye.
  9. Winnipeg80

    Winnipeg80 New Member

    Rubber Mounted?

    Could these kits be rubber mounted to the frame with a rubber spacer?
    I suppose it would have to be temperature resistant.
  10. fetor56

    fetor56 Guest

    Most ppl already rubber mount their kit to help isolate engine vibration & protect their frame & make more certain they don't sheer engine mounting studs,but there's more IF u wanna take the effort.The top of the head is where most excess movement occurs so if u could restrict this then you've done your best to ensure your engine remains isolated but rigid in it's frame.
  11. You know if your rubber mounting then this third mount is almost mandatory. Why?
    Because when my engine mounts get loose enough to move just a hair like I assume may be the case in a rubber mount,my engine anyway locks up a little sometimes when starting off and my chain is snug. When I tighten down my bolts the engine hardly ever does that,but more often when it's loose.
    As long as my mounts are tightened regularly I don't see a use for that myself except for that may keep my bolts intact.
    I'm a bit afraid to use loc tight in this area so I'd rather tighten it every week or two.
  12. mickey

    mickey Guest

    I like the idea of a third mount point for the engine, I just don't like that its attached to the poor 6mm cylinder stud.
  13. Demosthenese

    Demosthenese Guest

    agreed. mounting it to at least two would prbly be better.
    I used an old inner tube to rap my frame before u bolting the engine mount plate around the downtube. Inner tube seems to be very heat resistant, because the muffler presses right against it, and it does not burn or melt at all. I didn't expect that when i put it on; i thought i would have to trim it around the hot stuff.
  14. BoltsMissing

    BoltsMissing Active Member

    I posted the suprising results somewhere but not sure where, soere goes again.
    When I started my first build, it was on a 27" wheel frame and I had to carve a temporary woodone support to hold the engine in place while I drilled the hole through the frame.
    Aftert about 3 weeks of riding, the left pedal started to hit the engine just below the magneto cover. Obviously it dropped.
    So I got the original "tool" I carved out of timber, placed it under the engine again so it lifts it to where it should be, but this time I left the timber there for support. Then I tightened the bolt. It "felt" right for some reason.
    When I roads tested the bike, much to my surprise, 75% of vibration had vanished.
    I assume it's being absorbed by the natural nature of timber.
    The picture is not the latest of how it looks, I don't have a camera yet and I got booked by the cops for something else, there goes the camera money !
    But you can get a basic idea, I believe this method, when the bolt is tightened and the preasure is on the timber, the engine vibrations are absorbed.
    I cut and shaped the timber with angle grinder and bench grinder. Too easy.
    The rear spacing is seperated by cutting a piece of leather, an old trouser belt would do.Make sure it's leather.

    Attached Files:

    Last edited: Apr 1, 2008
  15. fastboy9

    fastboy9 Member

    very interesting, looks much more stable as well, this would actually look pretty cool with a bit of attention to cosmetics and on a cruiser/old style bike!
  16. BoltsMissing

    BoltsMissing Active Member

    The bracket however comes standard with the kit, but I did change the bolt,nut and washers.
    The rubber mounts are
    GM Steering Bushes. Part No: A92-1
    Made shims by grinding large washers into shape so it don't mess with the squaring on the rear mount bracket, so it stays straight.
    Don't just tighten the front bolt, and lever the rear mount, it might just crack the crankcase or something else will give in to the bolt tightening preasure.
    Make sure the preasure is on the Steering bushes, add shims if it tightens too far downwards if you are not using the timber.
  17. huckersteve

    huckersteve Member

    I love this. good post guys.

    Gotta try it!
  18. BoltsMissing

    BoltsMissing Active Member

    I hope you don't mean the wood piece. It lasted 5 months and it's only good for measuring, should update.
    What fastboy originaly posted is good to. But I still use leather between engine and frame where possible.
  19. huckersteve

    huckersteve Member

    No certainly not the wood piece, I wouldn't dream of calling a wedge of wood an "improvement" to my bike lol. Not that I'm disputing it served it's purpose for a time.

    I am always looking for improved mounting techniques and systems for my bike as the stock mounting configuration is pretty buzzy.

    I'm hoping to get home this afternoon in time to fabricate one of those top bolt brackets (two actually as I'll try it on two top bolts) before going to a rat bike rally down the road this evening. Probably won't come off in time but I'll be thinking about it and getting after it asap. Will post pics when finished along with feedback.

  20. V 35

    V 35 Member

    Eyebolts and coupler nuts would take away the ' hardware store ' look Cut off excess threads to clean up improvised designs. I like this concept, and would like to see more.