bicycle motor vibration

ZOOMCAT

New Member
Mar 14, 2008
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can anyone give me tips on lowering the vibrations on the old dog is there any motormounts that would work with my 70cc motor? thanks zoomcatrotfl
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
236
63
up north now
Re: vibration

A couple wraps of friction tape or gaffers tape where the mount contacts the frame help. Keeping the mounts tight help a lot too. Check them often.
 

Norman

LORD VADER Moderator
Staff member
Jan 16, 2008
2,605
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pampa texas
Re: vibration

I like to bed in the motor mounts by using a length of tubing same as on the bike. wrap the sand paper on the tube and sand away until the tube nests in the mounts. I've used Jb weld to bed in the mounts as well if the angle is not quite right get the mount almost tight and lay the epoxy in the mount area when it gets almost set sort of just past the rubbery stage tighten up the bolts/nuts, let it completely ride it then check to make sure the bolts/nut are tight. I recommend loctight blue on all mounts that don't use lock washers or fiber lock nuts.
 

Skyliner70cc

Member
Mar 8, 2008
138
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16
Re: vibration

I use thick foam grips on the handlebars and throttle grip! Really helps.

I've also found that vibration may be related to the bike frame and not necessarily to the engine. I've had bike frames that were awful and switching a "smoother" engine from one bike to another didn't do a thing.
 

General Disarray

New Member
Mar 15, 2008
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Re: vibration

Make sure your wheels are true and your rear sprocket is straight. Both of those will wear you out.
 

Egor

New Member
Jan 30, 2008
714
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Hurricane Utah
Re: vibration

Vibration - There seems to be a relation to the engines and who manufactures them. I take all my engines apart before I install them to see if the parts are in the correct order. I have one bike that is as smooth as glass, one that is a little worse and one that is horrible. The one that is the worst is the one that has no balancing holes in the flywheels. The engine came from Kings, they just turned the flywheels and assembled them. The engines from Dax have removable outer rings that are hollow in the correct places, it is just done in the castings but at least it is done. I have found that there are some frames that lend themselves to engines, one being the green Hawaiian bike from Wall mart, my Green Hornet. My pacific old bike is the one in the middle and the Schwinn is the worst. One thing I have recently found is that they need a hanger for the muffler I added one to the Pacific and it did a lot of good. I have tried to put rubber in the mounts and found that did nothing. Good tight mounts work. Have fun, Dave
PS: There is one fellow that added a mount to the bottom of the engine, a plate welded into the frame and picks up the bottom engine bolt, just an idea.
 

Riverdog

New Member
Apr 25, 2008
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Re: vibration

I have a 80cc on a stretch cruiser. So bad your hands get numbs at high RPM. Has anyone ever tried to balance a flywheel.
 

Dave31

Moderator
Staff member
Mar 1, 2008
11,204
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Aztlán, Arizona
Re: vibration

I have never had a problem with vibration, the only time a had a vibration is on my trip to Mexico when my front mount came loose.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
236
63
up north now
Re: vibration

Diamond frames seem to vibrate less than cruiser frames in my experience.

You can try filling the frame members with lead shot......there is a product called a ''bar snake" I believe that is just a long thin bag filled with lead shot and you put it in your handlebars (motorcycle) and that helps on bikes that vibrate.
 

Egor

New Member
Jan 30, 2008
714
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Hurricane Utah
Re: vibration

Their is quite a bit of science to the balance of a single cylinder engine. I took one of my 50cc Honda cranks and put it up on ways to see what Honda did. I then tried to duplicate it in the china engine. I ground away material near the big end and got the crank to stop with the big end straight out balancing the rod by the wrist pin straight out also. In a real balance there is a formula, you use a portion of the weight of the piston, pin, rings and rod. I just tried to get it the same as the Honda. Have fun Dave
PS: No it did not seem better.
I have a 80cc on a stretch cruiser. So bad your hands get numbs at high RPM. Has anyone ever tried to balance a flywheel.
 

Mini hog

New Member
Mar 26, 2008
13
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0
Milbank SD
Re: vibration

I have an idea that might help the vibration. I have some n.o.s. snowmobile engine mounts. They have a stud sticking out of each end with a "pancake" rubber insulator in between them. My plans are to use 4 of them and weld some cross braces to my bike frame and make coresponding braces to fit the engine mounts. In my mind, it "should" work. Anyone try this approach?
 

Egor

New Member
Jan 30, 2008
714
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0
Hurricane Utah
There is the thought that if you rubber mount the engine you can get rid of the vibration. On the other hand loose motor mounts can cause vibration. On the motorcycles we used to work on if a mount came loose it would knock the enamel off your teeth. I have four different engine company outfits. The dax is the best one for being vibration free, I rode it today and am still amazed at how well it runs. It is the only one that does not vibrate. I am tempted to install one of the other engines in this bike and see if the worst one will shake the Green Hornet. The newest one from Revolution I have to keep the revs down or it will shake the bolts off. One thing I don't know what would happen if you hide the vibration with rubber, I think the engine would shake its self to pieces and you would not know. Have fun Dave
 

toytime

New Member
Mar 20, 2008
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Ontario
I've always wanted to use Mini hogs idea but after reading Egors thoughts, I think he may have a point. I can almost picture the little engine vibrating right off it's mounts.
It has to be tried though and may end up being the best mod availible to us.
Hope to hear more on this Mini hog!
 

Egor

New Member
Jan 30, 2008
714
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Hurricane Utah
HookWorm - Yes on a slow revving engine that is a good answer. I do have a 39 tooth sprocket on the Green Hornet. I like the smaller sprocket keeping the noise down also. Have fun, Dave
Try switching to a smaller rear sprocket the engine won,t run as hard therefor you will have much less vibration.
 

MarkTur

New Member
May 23, 2008
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Wow - never heard of these guys, but I can drive there in about 45 minutes...cool. I'll have to take a ride down one weekend over the summer and check them out.

I like the air-filters!
 

MarkTur

New Member
May 23, 2008
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0
HookWorm - Yes on a slow revving engine that is a good answer. I do have a 39 tooth sprocket on the Green Hornet. I like the smaller sprocket keeping the noise down also. Have fun, Dave
I just picked up an "Upgrade Kit" on eBay from LiveFastMotors...$15 will get you a 40t sprocket, new chain, and a few other items...I'm currently using a 44t, and the entire reason I went with a smaller sprocket was to get rid of the vibrations at 25-26mph. Not planning on going much faster, but I should get a bit better gas mileage and of course lower the vibrations at that speed.

I have not gone any faster than 26.2mph (says my speedometer), so I don't know if it smooths back out at higher revs, but honestly, I don't want to find out. It sounds like I'm at the redline at 25mph... who knows, my throttle is only about 2/3 open...I know it will go faster, but do I really want my motor turning any faster?
 

Norman

LORD VADER Moderator
Staff member
Jan 16, 2008
2,605
2
38
68
pampa texas
You guys want to experiment with lowering your rpms and vibs?!
The front sprockets on most bikes will fit( teeth count from 36 to ?) the 415 chain the problem is getting that sprocket to fit the back wheel where the 415 sprocket goes. So this is where you have to get inventive. So there is some food for though now lets see what you all come up with!
Did that last line give away I live in Texas?!rotfl
Ride it like you stole it:ride2: