Sorbothane?

N

NeilJams

New Member
Hi everyone,

I know rubber is a big no no when mounting engines, but this being my first build I don't want to destroy my bike or engine and have read how metal to metal can cause headbolts to loosen just not as fast as rubber.

With that said I believe in today's day and age there has to be some kind of material that absorbs vibration instead of just redistributing it to the other parts of the engine. I was hoping sorbothane was that material.

Anyone recently use the stuff? I researched it on this site and there wasnt much on it. There seems to be a lot of mix feelings on vibration dampening on this site though.


I just want to limit the vibration on the frame mounts only, in hopes to limit the vibration the engine itself endures.

Thank you usflg
 
I dont know if this helps, but i know that Sorbothane is used in Kick-EEZ recoil pads for shotguns. And from my experience ive had pads last for 20+ years and only get softer and more absorbent of recoil over the years.
 
That's notable advise, thank you.

Question though, does the pad ever at any time of use, bruise or cause pain to ur shoulder?

Im curious if you bruise if it means that redistribution of the impact is occurring. If no pain or bruising occurs during use then I'll be somewhat hopeful that sorbothane does absorb vibration instead of redistributing it like rubber.
 
It isn't the material you use. It's the fact that when the engine is allowed to move in the frame it actually vibrates MORE than if it is mounted solid.

Yes, cars and motorcycles use resilient material in their engine mounts but the mounts are a totally different concept and design from your engine. They are a sandwich with no metal to metal contact between the mount fasteners and the frame. When you use rubber, or any soft material between the engine and the frame that material will compress and expand with each vibration cycle. The mount fasteners are then subjected to those vibrations and will loosen and/or fail eventually.

Soft mounting has been tried over and over and the results are always the same. More vibrations and failed fasteners and in some cases structural damage to the bike frame.

We always stress that a builder should build his bike as he sees fit. In other words, "build it your way". Nevertheless when you ask for advice or opinions you're going to get replies based on experience. That's why the majority of builders will tell you not to use resilient material in your engine mounts.

Tom
 
Can't say this doesn't suck, because I don't like hitting walls. I wanna break them down to keep going forward.

If there's a will there's a way. .trlrl.
 
Another point to consider is the fact that vibrations are inherent with any single cylinder, two stroke engine. It's just the nature of the little beasts. Some are worse than others by virtue of manufacturing inconsistancies (quality control) but they all produce those annoying vibes that most of us simply learn to live with.

Softer seats, hand grips and fat tires help make the ride nicer but that little engine is going to shake, to some degree.

Tom
 
If you look at some single cylinder motorcycles you will find that there is a head steady, connecting the cylinder head to the frame of the motorcycle. This changes the load paths of the vibration, and helps reduce the amount of energy going through the other mounts.

Has anyone here done this?
 
I purchased mine from Venice Motor Bikes, it's pretty smooth, I'm just looking for ways to treat it as good as possible.
 
Ludwig II said:
If you look at some single cylinder motorcycles you will find that there is a head steady, connecting the cylinder head to the frame of the motorcycle. This changes the load paths of the vibration, and helps reduce the amount of energy going through the other mounts.

Has anyone here done this?
Click to expand...
Like this one? I remember seeing a photo of someone here who was working on a similar design but I never saw any follow up report of how it worked. He used longer studs in the rear of the head and a wide strap that joined them to the frame. He had to remove some of the fin material but it wouldn't have been enough to compromise cooling.

Wish I could find that old thread but it was several years ago.

Tom
 

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Ludwig II said:
If you look at some single cylinder motorcycles you will find that there is a head steady, connecting the cylinder head to the frame of the motorcycle. This changes the load paths of the vibration, and helps reduce the amount of energy going through the other mounts.

Has anyone here done this?
Click to expand...

How would one attach it to a 2 stroke motor head? Motorcycle engines look like they're designed for the attachment.
 
Some of our communications have crossed in flight, it seems.

2door said:
Like this one?

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I remember seeing a photo of someone here who was working on a similar design but I never saw any follow up report of how it worked. He used longer studs in the rear of the head and a wide strap that joined them to the frame. He had to remove some of the fin material but it wouldn't have been enough to compromise cooling.

Wish I could find that old thread but it was several years ago.

Tom
Click to expand...
 
The other thing that people don't take into account with rubber mountings is that they are attached to load spreading areas, rather than being small high pressure contact points.
 
This is my first build so if you can't tell I really don't know much about motorized bicycle (except riding them.shft.). I am adventurous though and would like to explore all possibilities before I shut the door on the idea of stabilizing the little bastard.

I like the look on that head steady...looks like a safer direction to take too. Unless my 66cc 2 stroke China girl isn't meant to be stabilized. I suppose my real question should have been:

Are china girls meant to shake a little or can they be stabilized by any truly beneficial means?
 
I answered that question in post #6. Others might have opinons but what I posted can't really be argued with. All single cylinder 2 stroke engines will produce vibrations.

I feel you are overthinking this issue. Don't make your first build any harder than it needs to be. Install the engine as it was designed to be installed, learn some things about it and building a reliable and successful motorized bike. Then later, if you want to experiment and try new things you'll have some experience that will help.

Tom
 
I feel like most of the vibrations come from being so terribly off balance. A lightened piston can help this so much and makes these things a lot more fun to ride. Even a few grams lightened makes a world of a difference and it will help you crank out a couple hundred more rpms out of it. I think we need to step away from the mounting different ways to get rid of vibration and finding out why it vibrates so much in the first place. You can never balance a 1 cylinder engine, but you can make it better....
 
I got a new throttle from SBP and a hex bolt kit on its way. I'll blue loctite them and leave the stabilizing alone. Don't wanna beat a dead horse. I'll stick with the basics for now. Shame it's so hard to post pics even the one I was able to post isn't posting anymore.
 
NeilJams said:
I got a new throttle from SBP and a hex bolt kit on its way. I'll blue loctite them and leave the stabilizing alone. Don't wanna beat a dead horse. I'll stick with the basics for now. Shame it's so hard to post pics even the one I was able to post isn't posting anymore.
Click to expand...

Best thing is to host them on a different site IE Imgur.com and link them via the insert image button on advanced. Works everytime and you'll always have that picture stored off to the side.
 
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