ive read a thread or two on whether to isolate motor from frame with innertube..tape...etc or mount without to reduce vibration....does the innertube just dampen the vibration you feel or is it good to use the frame to absorb vibration and allow the engine to last longer(bolts..fasteners...etc)?...im going to mount my engine soon and really need some input on whether to add rubber or mount solidly.
solid or rubber mount engine?
- Thread starter macattie88
- Start date
* Warning do not do anything that i do on my bike,as it may not work the same for you *
I cut rubber handle bar grips in half and taped that where my engine mounts mount to using black elcetrical tape. It gets rid of almost all the vibrations.
You should just put tape on the frame and mount the engine regular without rubber and see how the engine runs and break the engine in first. That way you can't blame the rubber for your studs breaking or engine falling off. Plus im sure most of the others will tell you to solid mount the engine to the frame.
They don't have a rubber mount in the box cause its a cheap kit from china and were lucky to even get the parts we do get.
I cut rubber handle bar grips in half and taped that where my engine mounts mount to using black elcetrical tape. It gets rid of almost all the vibrations.
You should just put tape on the frame and mount the engine regular without rubber and see how the engine runs and break the engine in first. That way you can't blame the rubber for your studs breaking or engine falling off. Plus im sure most of the others will tell you to solid mount the engine to the frame.
They don't have a rubber mount in the box cause its a cheap kit from china and were lucky to even get the parts we do get.
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solid. if you want to run a piece of innertube around your frame, that's probably ok, as long as the motor doesn't move at all when it's tight. something that small wouldn't really have any effect on vibration.
people say they've done that to save the paint on their frames, but it ain't really gonna help, and if you have a crappy paint job, it'll stick to the rubber and peel off when you disassemble it.
i've said it a bunch of times, but here goes again...
with the motor mounted solidly, it'll transfer the vibrations through the rest of the bike. so build a solid bike, and your bike will have very little vibration.
tires help a lot, too. knobby tires will give you more road vibrations than your motor will put out.
as a simple example of dampening vibration, pretend your engine is your cell phone set on vibrate. if it's on your bed when it goes off, it just sits there and vibrates like crazy. the bed is the rubber mount. it's not moving, but your phone is. there's nothing to dampen it. that's why studs break and motors fall off.
if your phone goes off on the coffee table, it'll vibrate itself onto the floor. but if you held it down on the coffee table, the vibrations will transfer to the coffee table (your frame) and through your hands (the tires, grips, you, etc...) and smooth everything out.
i think.
people say they've done that to save the paint on their frames, but it ain't really gonna help, and if you have a crappy paint job, it'll stick to the rubber and peel off when you disassemble it.
i've said it a bunch of times, but here goes again...
with the motor mounted solidly, it'll transfer the vibrations through the rest of the bike. so build a solid bike, and your bike will have very little vibration.
tires help a lot, too. knobby tires will give you more road vibrations than your motor will put out.
as a simple example of dampening vibration, pretend your engine is your cell phone set on vibrate. if it's on your bed when it goes off, it just sits there and vibrates like crazy. the bed is the rubber mount. it's not moving, but your phone is. there's nothing to dampen it. that's why studs break and motors fall off.
if your phone goes off on the coffee table, it'll vibrate itself onto the floor. but if you held it down on the coffee table, the vibrations will transfer to the coffee table (your frame) and through your hands (the tires, grips, you, etc...) and smooth everything out.
i think.
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Do not...Do not, mount the engine in any type of resilient material. The more solid you can mount it, the better off you'll be. You'll have less vibration and potential fastener failure if you mount the engine the way it was intended to be mounted. The more contact area you have between the engine and the bike frame the more the inherent vibrations will be absorbed by the frame and less will be transmitted to other parts like the engine mounting hardware. Even thin material, like inner tube, which will only protect your paint to some degree will adversely effect the vibration issue. Mount it solid, and you'll be ahead of the game.
Tom
Wish I'd have thought of the pager on the bed thing...
Tom
Wish I'd have thought of the pager on the bed thing...
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I understand, I guess I just don't agree. Again, I'm a 4stroke guy and am not familiar with the 2strokes except for the few that I have seen. I built a mount for my 4 stroke that worked great. I do see the main difference in how the mounts are that could lead to a bolt failure in the 2 strokes, but it seems more like a design issue with most of the isolating methods rather than it just being taboo to do it. You have to admit that we are not dealing with race car type horsepower here.
I have 0 vibration, My engine does not move at all and we all know how my engine is mounted. I never had no broken bolts. My muffler strap also helps to keep my engine tight to the frame. But for a test i will solid mount my engine to my bike frame and we will see. But if it vibrates like a wild circus amusement park ride and i twirl around in circles and my body vibrates for days i will be listing the results here and on every forum.
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I will agree to that, but the engine is vibrating because of a balancing issue. It doesn't matter how rigid the mount, you are not going to stop the vibration. Such as the phone example, holding it down tight doesn't keep the phone from vibrating, it is just redirected rather than isolated. With that type of vibration, something is eventually going to give. I guess it is a personal preference. I would rather have a smoother ride with possibly having to change a mount every now and then rather than have my pedals and fenders fall off from the high frequency vibrations running through the frame. Please remember that I have a 4 stroke that has 4 mounting bolts in the bottom of the engine, I have no experience with a 2 stroke. A proper isolating mount doesn't have any energy absorption material directly between the engine and it's primary mounting surface. This is why the bolts break. There should be a primary mounting plate bolted to the engine directly, absorption material in between, and a secondary mounting plate bolted to the frame seperately from the engine bolts. I am not implying that they will never need replacing, but it will effectively isolate the vibrations from the frame of the bike and provide a better riding experience, in my opinion. And yes, I know what my opinion is worth. That's why I'm not charging for it!
I want my frame to feel like that bed, from the example given! The engine is just vibrating away and I can't feel it. I think that was a good example too.
I want my frame to feel like that bed, from the example given! The engine is just vibrating away and I can't feel it. I think that was a good example too.
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exactly. now, if our motors had, say, four mounting points in the frame spaced out equally, a rubber mounted situation would probably work perfect. it would allow the motor to vibrate, but it would vibrate equally, or uniformly inside of a cradle. if balanced correctly, one vibe would cancel out another, and they would all share an equal load.
our main problem is we have two unbalanced, uneven mounting areas, attached to basically whatever we can find to bolt it to.
it's like a front wheel drive car with a broken torque strut (usually a dog bone lookin' motor mount if you haven't seen one.) as the name implies, when the car accelerates, the motor wants to twist. the torque strut keeps it from doing so. with a broken one, it will twist, and mike breaks an axle (i had a 75 civic hatchback with a non-cvcc 1600, dual mikunis, etc. 1/4 miled in 12's. had to build all solid motor mounts
)
now, applying this to our little two stroker, the torque is provided by the chain, especially at start up, where it wants to (and does) jerk the whole motor to one side, the engine chain side. there's no lateral mount, so we have to rely on the two in-line mounts to keep that motor from twisting.
with a rubber mounted set up, it will twist, and shear off the motor mount studs, or twist the rear wheel off it's axis if not tightened properly, or the motor flops completely out of the frame (all problems encountered on this forum.)
and honestly, if the motor was better balanced and we were able to mount it properly and securely, a cushioned motor mount would probably be freakin awesome.
our main problem is we have two unbalanced, uneven mounting areas, attached to basically whatever we can find to bolt it to.
it's like a front wheel drive car with a broken torque strut (usually a dog bone lookin' motor mount if you haven't seen one.) as the name implies, when the car accelerates, the motor wants to twist. the torque strut keeps it from doing so. with a broken one, it will twist, and mike breaks an axle (i had a 75 civic hatchback with a non-cvcc 1600, dual mikunis, etc. 1/4 miled in 12's. had to build all solid motor mounts
)now, applying this to our little two stroker, the torque is provided by the chain, especially at start up, where it wants to (and does) jerk the whole motor to one side, the engine chain side. there's no lateral mount, so we have to rely on the two in-line mounts to keep that motor from twisting.
with a rubber mounted set up, it will twist, and shear off the motor mount studs, or twist the rear wheel off it's axis if not tightened properly, or the motor flops completely out of the frame (all problems encountered on this forum.)
and honestly, if the motor was better balanced and we were able to mount it properly and securely, a cushioned motor mount would probably be freakin awesome.
It would vibrate because its mounted to a large metal frame with fenders and stuff.
I did stop the vibration. My fenders are also rubber mounted and dont vibrate.
The muffler strap and my custom front mount stops my engine from twisting side to side.
The reason people break bolts is that they don't use a muffler strap or any extra straps at all.
And for those people i reccomend they mount there engine solid mount.
I did stop the vibration. My fenders are also rubber mounted and dont vibrate.
The muffler strap and my custom front mount stops my engine from twisting side to side.
The reason people break bolts is that they don't use a muffler strap or any extra straps at all.
And for those people i reccomend they mount there engine solid mount.
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civ, i made a thread about fenders. i actually rubber mount my fenders, chainguard, coaster brake and drum brake strap, muffler clamp, etc with innertube pieces or whatever.
if you keep all the parts from vibrating, they won't fall off.
if you keep all the parts from vibrating, they won't fall off.
I commend all of you guys for the work and trial and error that you have put into these things. I can see what you are saying about starting the engine. As I said, I've never owned a 2 stroke. It still seems to me that stoping the problem at the source is much better than trying to prevent all of the shady results, such as all of the mods you listed above. When I built my stretch the first time, the engine had such a high frequency vibration that my hands and feet would get numb in about 3 miles. One of the pedals fell off when I was riding and my fender mounts broke. After toying with it for a while I built my idea of an isolating mount and problem solved. I did a thread on it too. It's in the 4 stroke kit area called Anti vvvvvibration mounts for us. I am pretty sure that you guys have inspired me to get a 2 stroke to play with.
I recommend mounting the engine solid!
There are way more people here who've created more problems for themselves from using the rubber mounts than people who've had success with them.
I use the 'kiss' philosophy of mechanics... (keep it simple stupid!)
There are way more people here who've created more problems for themselves from using the rubber mounts than people who've had success with them.
I use the 'kiss' philosophy of mechanics... (keep it simple stupid!)
Im keeping my rubber mounts,my bike runs great and has no vibrations.
My engine is mounted rock solid,has 2 mounts(front is custom) and i have a muffler strap connected to my bike frame,plus im adding a top strap from the head to the top frame.
Ive had a little carb problems,but i swap the carb for another one i had.
But all new people should mount your engine solid.
My engine is mounted rock solid,has 2 mounts(front is custom) and i have a muffler strap connected to my bike frame,plus im adding a top strap from the head to the top frame.
Ive had a little carb problems,but i swap the carb for another one i had.
But all new people should mount your engine solid.
I got a Lexus motor in my car and its has the hardest and as close to solid mounts as is recon ya can get. The motor does not move and i have placed a 50cent piece on the rocker cover and reved it to read line and it is still standing (lexus test not mine)
If the rear motor mount is square and solid against the down tube you will have less vibration.
If the rear motor mount is square and solid against the down tube you will have less vibration.
The rear motor mount should be square and solid against the seat tube. The front motor mount should be square and solid against the down tube. Then you are set!
