new project ,,motor mounts

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japat100

Guest
we all know that vibration is a killer , it is also very unpleasant ,, and it also causes noise level to rise ,so it would be the single biggest improvement that anyone could make on these 2 cycle mb .. and as it stands now the method is to bolt down tight the motor to the frame and let the frame absorb the vibration , then bolt everything with lock nuts ,lock tight onto the bike ,, in my view it is not the answer , if we all believe that this is the only way to do it,, we are not going to solve the problem ,,

it is not a hypothesis nor a theory but a law that if part 1 vibrate ,and it is mounted to part 2 by means of rubber compound or alike ,that only a fraction of the vibration will be induced to part2

from what i understand from senior members is that when these motors are set in rubber that they are not stable enough ,and will twist and bend putting everything out of alignment etc . so what then,, take out the rubber, take out the wrenches ,and tighten everything down with lock tight etc. ,, in my view that is not going to solve the problem
the answer will be found by adding another motor mount to the top part of the cylinder also set in rubber .now if you look at the angles of all 3 mounts and where they are located ,you can see why that the third mount set in rubber will secure the aliment etc. .making the motor plenty stable

i have about 5 projects going in my machine shop at this time ,, but i going to find time to prove the point , that 3 motor mounts set in rubber will be a great improvement ,, my hope is that if all works well that a simple adapter plate set in rubber ,,,that fits between the frame and the motor can be made available to all members ,, and i am sure there are lots of members out there now that can think of ways to add the third mount to the top part of the cylinder ,, and that whats makes this forum great the collections of minds ,to improve product and pass it on to the importers ,and manufacturers ,and let them add the third mount ,


we should never say this is good enough , but always try to improve ,and if we don"t get it right this time ,we will get it right next time ,and a very good example of that is auge light system ,with many ups and downs ,,he never gave up
japat
 


srdavo

Well-Known Member
Joined
Nov 4, 2006
Messages
3,157
we should never say this is good enough , but always try to improve ,and if we don"t get it right this time ,we will get it right next time japat

I appreciate projects to improve the quality of our builds.

Most times I wrap the mounting points on my bike frames with innertube. My Schwinn frames actually need this to fill the mounting clamps. (I always wrap the mounting points on fuel tanks....the rubber grips well & and I don't have to over tighten the studs on the tank...risking twisting one of them buggers out of the tank)
I realize this is a far-cry from rubber mounting. my bikes vibrate plenty!!

My buddies Harley engine is rubber mounted nicely. No vibration felt on the bike...except you could shake a can of paint between the jugs. :LOL:

which leads to my question.....Once we contain the vibration to the engine only, how will the engine hold up? I mean...the vibration is not going to magically go away..... or is it??

I am going to follow this project...... I like it!
 
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andyinchville1

Guest
Glad there are a lot of tinkerers on here! ;-) Be interesting to hear you findings.....I personally have not been really bothered by the vibrations but maybe because that is because it is all that I have known.....Of course I used to pedal a lot too...HA.....

One idea I had thought of as far as reducing vibrations was to fabricate blocks of urethane
to replace the aluminum mounting blocks.....urethane (like they use in high performance bushings for autos and trucks), may be stiff / strong enough to resist motion of the motor while at least offering some degree of vibration absorption....

Just a thought....but I like your 3 point mounting idea too...it would be great if the 3rd mount could be a simple bolt on...

Tinker on!

Andrew
 
J

japat100

Guest
I appreciate projects to improve the quality of our builds.
which leads to my question.....Once we contain the vibration to the engine only, how will the engine hold up? I mean...the vibration is not going to magically go away..... or is it??


interesting question ,, vibration which is a form of energy can"t disappear,unless you have perfect balance ,,and we in this case don"t have perfect balance


the high end vibration is what causes problem , ,
vibration is as you know is a movement ,,the shorter the movement the higher the vibration and the faster it vibrates ,, when you bolt down tight a motor to the frame the frame shortens the movement and that causes a higher pitch , the amount of energy that was transfered to the frame must be accounted for so what happens is that the whole frame must absorb the vibration at shorter movement to get rid of the energy .

by adding good motor mounts you keep the vibration at a lower pitch ,, since i understand there is no fly wheel or counter balance the vibration is cause by rpm . so there for if rpm is at 5,000 the movement can be no faster then 5,000 which is not a very high pitch ,, however there is also the length of movement that i am concerns about ,if my motor is anywhere close to balance it should not be a problem ,


yes let the motor vibrate and the lass thing i want to do is shorten the movement by bolting it down tight to the frame ,and i end up siting on part of the frame

the lower or longer movement vibration is also much easier on the motor ,,could get 10,000 or 20,000 miles on my motor ,asked yourself why not ???, like i said before a power saw wide open 40 hours a week is good for 5 years ,no matter what type oil they use ,allot of saws motors are set in rubber ,,so 40 hours by 52 weeks by 5 years how far could you go on your bike ??? at least around the world once ''and a 32 sprocket may get you to the moon ,

and to add a short note to my post i will be killing 2 birds with one stone that i expect the noise level to be reduces by 50 percent ,by adding a third mount

sure tell me nuts' could be i ride a mb
japat
 
J

japat100

Guest
Glad there are a lot of

....but I like your 3 point mounting idea too...it would be great if the 3rd mount could be a simple bolt on...

Tinker on!

Andrew

if you look close at the angles the third mount only need to keep the motor from going side to side for now to prove the point ,,

and i hope some day that the third mount would be part of the engine block , and i hope that the motors we now have could have adapter plate available so the whole motor could set in rubber ,,, what a difference in he ride ,and to save the hardware
japat
 
5

5-7HEAVEN

Guest
:cool:Many higher-end pocket bike engines have an upper motor mount molded into its cylinder. i've noticed that the mount's swivel is parallel to the engine crankshaft.

since i'll be running twin 80cc engines in my project cruiser bike, vibration will definitely be a problem i need to solve. gathering from what you all have offered, using a 36t sprocket and keeping operating rpms lower should help keep engine vibrations down to just a rattling nuisance at idle...i HOPE.:rolleyes:
 
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