Rubber mounting... again (isolation)

J

Jeckler

New Member
So in the reading I've done over the last week, it's been said not to mount the CG's with rubber on the mount, as all it does is transfer the vibration to the fastener which can cause it to fail, and doesn't really help. Rubber isolated mounts are better, but I haven't seen any posts where people have tried them or not. I'm also not sure of the forces that may be transferred through them. I found a website that sells rubber isolated mounts though, and wanted to get thoughts on viability.

http://www.vibrationmounts.com/Store.asp?Page=Products1.htm

On this page, down near the bottom is a selection of mounts that may do the trick. They will obviously require custom frame mounts, but that hurdle seems to be well covered. Here's an example.
The diameter would have to be such that two of them could be mounted on the engine studs, which limits them to about 30mm each (15mm radius, 40mm between the studs, for a 10mm gap?).
Thoughts? Am I too new at this to make such a suggestion?
 

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They are the closest thing to how motorcycle, car, outboard, etc. engines are mounted.
They consist of a steel, rubber, steel sandwich which isolates the mounting fasteners from the vibrations produced by the engine. The hurdle will be to find them in a proper firmness that will absorb vibrations but not allow any engine movement.

Our bikes are similar to motorcycles in the way the power is transmitted to the rear wheel in that the engine can not be allowed to shift from side to side or front to back because in doing so you effectively alter chain to sprocket alignment. This is critical for a trouble free chain drive.

Many before you have tried to control the vibrations inherent with a single cylinder 2 stroke engine. You are correct about custom fabricated mounts to work with those rubber isolators. Unless you have access to a welder that can be a problem. Good luck and let us know how your idea works.

Tom
 
Howdy Jeckler. Welcome to the forum.

Cool link and thanks for posting. I was looking around for such, for another project.

Folks are gonna yell at me for this but think the main cause of heavy vibration, is we just ride em so hard and red line em. It has been a few years since I have read the fed. guidelines, but do believe they state 20 MPH. So our China Girl's engines were designed with this speed as a cruising speed. They purr happily at those RPM, after much more, is red lining.

Amazes me thing so simple can put up with how I abuse em.

But any way, thanks for the link and great to meet you.
 
Dan said:
Howdy Jeckler. Welcome to the forum.

Cool link and thanks for posting. I was looking around for such, for another project.

Folks are gonna yell at me for this but think the main cause of heavy vibration, is we just ride em so hard and red line em. It has been a few years since I have read the fed. guidelines, but do believe they state 20 MPH. So our China Girl's engines were designed with this speed as a cruising speed. They purr happily at those RPM, after much more, is red lining.

Amazes me thing so simple can put up with how I abuse em.

But any way, thanks for the link and great to meet you.
Click to expand...

I must say since I swapped to a 36t sprocket, I feel MUCH less vibration at normal cruising speed. I realise some people have hills to deal with, but raising the gearing is one simple way to cut vibration if you live in a flat area.
Lower rpms=less vibration. Plain and simple.
 
Welcome to the forum jeckler.
Many have tried, Many have failed. But I've never seen it done your way so I can only wish you the best of luck. Like 2door said, The main problem is engine movement. I've seen some ideas with a third top mount that might work, But haven't ever seen a finished product.
And hey Dan, (how ya doing today?) I ride mine WOT most of the time. If the mounts are TIGHT vibration is minimal.If you've ever had a mount loosen up on a ride you know the difference. First time it happend to me I thought my engine was taking a dump. And by the way, The speed limit for a gas motorized in California is 30mph. 20mph for electric. My bike is hitting 35mph and I would get ran over on a slower bike. San Jose cagers are NUTS.
fatdaddy.
 
in my experience with these POS MABs - whenever the motor can move in relation to the rear sprocket & chain, it will cause chain problems - seems to only take 1/4inch or so of unexpected movement to get the teeth to hit the side plate of the chain rather than the center gap
 
Hello Jeckler, here's a link to a vibration reduction article, but not to do with mounting. Good luck, Chaz
 
That won't work.

Apparently I'm the only one smart enough, and humble enough to do it right.

This was my first motor bicycle, that I made before anyone told my you can't do it this way. The rear mount is stock, with one thin layer of inner tube wrapped around the seat post. The front mount is made from a hockey puck, and an automotive muffler clamp. It has over 2000 miles on it and it still works great. It does slightly reduce vibration. The trick is it's very solid feeling. There's only a very slight hint of flex if you grab the head and try to move the motor. That's about all the vibration dampening you can get away with, but it does help. I've made 3 motor bicycles using this mounting method and none of them have had a problem with it.

picture.php


There's a good look at it toward to end of this video.

http://www.youtube.com/watch?v=2DUHadQpNnQ
 
fatdaddy said:
Welcome to the forum jeckler.
Many have tried, Many have failed. But I've never seen it done your way so I can only wish you the best of luck. Like 2door said, The main problem is engine movement. I've seen some ideas with a third top mount that might work, But haven't ever seen a finished product.
And hey Dan, (how ya doing today?) I ride mine WOT most of the time. If the mounts are TIGHT vibration is minimal.If you've ever had a mount loosen up on a ride you know the difference. First time it happend to me I thought my engine was taking a dump. And by the way, The speed limit for a gas motorized in California is 30mph. 20mph for electric. My bike is hitting 35mph and I would get ran over on a slower bike. San Jose cagers are NUTS.
fatdaddy.
Click to expand...

Hey FD. How goes it Buddy?

I agree, right and tight is the way. Here in CT, there is no speed limit on a motorized bicycle (motor driven cycle) Other then posted for any vehicle. Just has to be under 5 HP (nananna, LOL) and have a seat height of over 26" The federal guidelines are just what I thought our 2 smokes were designed for.

The laws changed here in 2008 and now I can't find the fed statute other then referenced to state; http://search.usa.gov/search?utf8=✓...ed+bicycles&m=&affiliate=usagov&commit=Search
 
I'd like to see a 212cc Pred mounted to a frame with hockey pucks.....it would prolly be spiriling down the street throwing bits of chain everywhere. El rollo anyone? laff
 
scotto- said:
I'd like to see a 212cc Pred mounted to a frame with hockey pucks.....it would prolly be spiriling down the street throwing bits of chain everywhere. El rollo anyone? laff
Click to expand...

That's why you're only my assistant know it all.
 
Jeckler, it is a great idea and don't give up! I can not tell you how many times I have seen just this sort of thing happen. Folks getting talked out of trying some thing just because it has always failed before. Do some thing great and prove us all wrong.. I will be only one of the people applauding you.

I have been at this for a few yrs but have seen some amazing builders and tinkers do just that. Create some thing incredible. Don't give up the ship until the water is over the tops of your boots. (then jump Forest)

Honestly, the only way I can see it being done is a hydraulic front mount and a rear that pivots. it would cost many times what the kit does but the point is to build some thing cool. One of a kind and ground breaking.

Is it worth it? Pretty much, no. IMHO. Every thing about building an any thing is about the compromises. This can be won but is the challenge worth the cost?



But you will be the one who did it. Build some thing cool.
 
Motorcycle Manufacturers rubber mount all their engines, BUT if ya notice, It's at at least three points (or more.) And with NO MOVEMENT of the engine whatsoever. They use a very hard rubber. ANY engine movement is too much. Even 1/8" will throw the chain out of alignment. If the chain is not hitting exact center on the rear sprocket at all times then you need to adjust the sprocket to do so. If the engine moves AT ALL then you need to figure out another mounting system.
All I'm trying to say is rubber mounting might work, I just dont think it can be done with only two mounting points. (JUST MY OPINION,) But, using auto engine mounts at three points (or more,) I think has a chance. So be the Underdog bro and prove us all wrong. If you make it work get a patent before you show it to anyone, (except me, LOL.)
fatdaddy.
 
tunerhead001 said:
You could the JNM Super Mount, with its pre-made rubber mounts. Looks like it could be pretty effective.

http://www.jnmotorsbikes.com/product_p/jnm1102.htm
Click to expand...

Hey tuner, STILL it's just putting rubber on the mounts. You can do the same thing yourself for a lot less than $25.(plus shipping.)
But any rubber mount I've ever seen INCREASES vibration. Just because a vender makes a claim doesn't make it true. When I was a newbie I tried rubber mounting. It NEVER worked any better, and usually not as well, as the simple mounting system supplied with your kit.
fatdaddy.
 
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