Additional Mounting and Vibration Reduction Tips - Please Provide Feedback THX

[bakaneko]

Hello. I wanted to share some "tips" on how I stabilized and reduced vibrations on my 66cc 2-stroke motorized bike. I think this will help those who cannot use the U mounts or want additional mounts. It seems excessive vibration causes a lot of issues such as low speeds, cannot ride bike above X speeds, bubbles in carb bowl, electrical breakdown, and etc. Note, I am a relative newbie (2 months) and appreciate some criticism or feedback.


1. Large hose clamps to support mounts - I bought 2 large hose clamps and wrapped them around the two mount areas. I tightened it using a screwdriver and then used a wrench with a screwdriver to apply max tension. The hose clamps are very strong and I feel they will last a long time. I like this tip the best as in case the mounts fail (bolts, nuts); the hose clamps are more than enough to operate the bike. Total cost = $4 (2 for each from Menards) Nice insurance right :helmet:




2. Horizontal bar across upper chain side of engine - I noticed that obviously the engine vibrates more near the top of the engine rather than at the mounts. I didn't like the vibration and how it affects the carburetor so I placed a single non-bendable, high quality metal bar across the top of the engine and mounted the ends to the bike frame. To hide the unsightly bar, I placed the chain guard but a nice piece of metal cover would also do or you could just not hide it. I attached the bar to the bike using hose clamps and high tension from the bar. Additionally, I am not sure if this is entire true, but I think it helps dissapate heat better from the engine due to head transfer to large bar and then attaching metal. Total cost = $5 ($2 for bar $3 for clamps)




Well, that is it. I would love to hear what fellow motorized bikers think or if there some catastrophe I do not foresee. Note, there are different type of hose clamps with varying strength and costs.

 

[bluegoatwoods]

All in all I say, "Good thinking".

It's important that these engines stay just where you put them on the bike, and you've achieved that. It might be unsightly. But only to those of us who're familiar with these bikes and motors. But John Q Public won't know the difference and you have a solid mount.

 

[bakaneko]

All in all I say, "Good thinking".

It's important that these engines stay just where you put them on the bike, and you've achieved that. It might be unsightly. But only to those of us who're familiar with these bikes and motors. But John Q Public won't know the difference and you have a solid mount.

Thanks, m8. Yeah, I don't think it looks too bad with the chain guard covering the bar; kinda cool actually . I mean it is like $10 for an additional mounting fail safe with the added benefit of additional stabilization and vibration reduction.

And, the other thing I learned is that there are different grades of bolts with varying strength. I would replace all the Chinese heavy load bearing bolts (muffler, mounts, and piston head) with high grade "American" bolts.

 

[butre]

looks gross but there's nothing wrong with a bit of jerry rigging

 

[bakaneko]

looks gross but there's nothing wrong with a bit of jerry rigging

yeh looking at it now. it does look kinda gross. I will make my next build much cleaner and with an outer frame to hide the engine and gears!

 

[KCvale]

Note, I am a relative newbie (2 months) and appreciate some criticism or feedback.

All gas engines have some vibration simply by the up/down movement, severe vibration is caused from an imbalance, in the cheapo 2-stroke engines it is usually the crank shaft but it could easily be the piston or rod or even the bearings if it uses them, the really cheap kits use bushings!
It could also be caused by misfiring or poor fuel mix.

Vibration grows force exponentially.
This is easy to see in an upright washing machine with an unbalanced wet load on spin cycle.
It grows until the washer starts walking around to dissipate the force.

With a washing machine you just balance the load, or bolt it to the floor and force the machines bearings to dissipate it that way.
For an engine all you can do is balance it, or dissipate it through the bike frame.
In short, make the engine one with the bike frame.

1. Large hose clamps to support mounts.

Hose clamps work well when they are around something round and straight.
They don't care for bends and angles and tend to slip and loosen so keep an eye on them.
A fine safety feature though!

Well, that is it. I would love to hear what fellow motorized bikers think

Give your engine mount the 'shove test'.
Grab your top bar over the engine with 1 hand, and grab your engine head with other hand and
then try to shove your engine back and forth AS HARD AS YOU CAN.
If it moves in the frame AT ALL that is a fail.

Even a little vibration will grow if not 'bolted to the floor', in this case the frame.

That will keep the vibration from growing and breaking things.

That means the vibration is in the bike itself now and why you have to really secure everything so it doesn't feed the vibration.

You dissipate some of vibration through the handlebar grips.
That is where I dissipate vibration before my hands, at the grips.

The very first thing I hated about my very first build was the kits hard plastic grips, so that was the very first thing I had to change.
The most annoying thing between the bike and I was the grips.

I use pretty much generic BMX grips, which are simply black pipe insulation but a bit denser and the packs have end caps and rounded edges, and they stretch.

The plastic throttle barrel is bigger outside than a regular grip is inside.
I just use a utility knife to cut down the length of the throttle barrel grip and peel it off of the plastic throttle barrel, and throw both grips in a box.

A little soapy water and you can massage a foam grip over the throttle barrel.
The left side of course fits easy and pretty darn good at dampening out vibration before it hits your hands.

So good, by my hands assessment, I haven't used hard plastic kit grips on my builds dating back to this one in 2010.

~$12 for enough to replace the foam a couple of times as they don't hold up to weather well.

Just a tip, another is pull that skinny spring off you clutch cable between the arm and cable stop.
It's sole purpose in life is to make your clutch lever harder to pull ;-}

 

[Deleted member 12676]

Instead of southern engineering it, why don't you take the crank out and drill the flywheels for better balance?

 

[bakaneko]

Very nice clean looking bike there KCVale. Thanks for the test idea. I performed it and there is no movement that I can detect . I also was thinking about your handle bars and vibration dissipation point. Currently, I am using the handle bars that came with the kit, which feels somewhat plastic and somewhat rubbery. I had some pure cheap rubber grips on the bike prior. I wanted to experiment today with placing the rubber grips (as much as possible) over the plastic/rubber grips from the kit to see if this helps reduce vibration even more. But, atlast, it rained all day here in Wisconsin. I will report the results of this test tomorrow if I can get a ride in between the rain.

Jaguar, yeh, I am not too mechanically proficient so this is probably the reason why I had a vibration problem. I don't think I can even attempt to drill out the flywheel without really screwing something else up.

 

[The_Aleman]

Stuffing corks from wine bottles in the handlebars and seatpost can help a little bit. I've been doing that on my bicycles for over 20 years - excessive vibrations make my hands go numb.

#1 cause of chinagirl vibration from my experience has to do with method of engine mounting. I recommend using a u-bolt-type front mount and make sure the rear mount is flush on frame.

If you can't run a u-bolt-type front mount, make sure both mounts are tight and flush on frame (have full contact). Some grinding of the engine's mount base may or may not be required.

Some chinagirl engines are terribly balanced tho - they may always vibrate excessively. My own first engine was like that, it ended up shaking itself to death lol

 

[KCvale]

Very nice clean looking bike there KCVale.
Thanks for the test idea. I performed it and there is no movement that I can detect .

Excellent!
We have been doing 'the test' for so long that it doesn't matter what it is or even the reason it's here, that is test #1 almost instinctively.

I wanted to experiment today with placing the rubber grips (as much as possible) over the plastic/rubber grips from the kit to see if this helps reduce vibration even more.
But, alas, it rained all day here in Wisconsin.

Weather has to be #1 reason MB's are just not popular this time of year, bad weather in so many places.
Then again, when it's time to put the snow blower and snowmobile away the MB's come out.

Stuffing corks from wine bottles in the handlebars and seatpost can help a little bit. I've been doing that on my bicycles for over 20 years - excessive vibrations make my hands go numb.

Cool tip, thanks Almen, I save wine bottle corks anyway as they do tend to work in a pintch for many things, especially in my boat days.

#1 cause of chinagirl vibration from my experience has to do with method of engine mounting.
I recommend using a u-bolt-type front mount and make sure the rear mount is flush on frame.

If you can't run a u-bolt-type front mount, make sure both mounts are tight and flush on frame (have full contact).

100% full agreement here, and the advice every new builder should hear before even starting a build.

Some chinagirl engines are terribly balanced tho - they may always vibrate excessively.
My own first engine was like that, it ended up shaking itself to death lol

I have pretty much just used Yang Dong factory engines, (aka Skyhawk), they go the extra mile for quality, but I have sure seen some in here for repair.

Well, not repair sadly, more like an autopsy.
Cause of death?
$99 2-stroke kit on a $99 Wally World bike sold on CraigsList for $350 when the builders first ride around the block and the first problems started.

The buyer got stuck with a bike that was toast before the thing even made it past break-in gas mix.

And then there are the first time builders that tried and then come to me.
If the only thing they want is to 'make it go' so they get their $200 back I send them away with a bit of advice.

I have seen the disappointment in so many eyes too many times when their last $200-$350 lottery ticket for cheap reliable transportation didn't win I have to speak up.

It starts with makers of crap in the first place.
It ends with those that build with it.

If you build it to sell, use the good stuff and make it safe please.
It is not just peoples livelihood, it's their actual lives.

If you built it for yourself and it's junk to start or simply worn out, take the loss and move up.
At least, please, disclose everything before you try to sell it, screwed poor people have the kind or eyes you don't ever want to see, let alone cause.