To "rubber" or not

gphil · Feb 18, 2011

Reading through the texts here question comes of to put a cut inner tube under the mounts. Now my instructions say to do so and hold it in place with some black elec tape. Now I did read , 2 Door , I think said to mount engines real firm. I have to agree with him but my instructions say rubber. Any takers?? Too old to worry bout a little paint chipped. lol gphil brnot

2door · Feb 18, 2011

You're going to get several answers here but the majority of experienced builders will all agree that mounting the engine as solid as you can is the way to go.
Soft mounting doesn't eliminate the source of the vibrations which are inherent with a single cylinder 2 stroke engine. It only transfers them to the engine mounts and fasteners.
Give it a day or so and read what others will tell you. In the interim use the search feature at the top of the page and read what has been written about this subject in the past.
Wrapping the frame with a layer or two of vinyl electrical tape won't effect the mounting but might serve to protect your paint. Forget the inner tube. It serves no purpose.
Tom

gphil · Feb 19, 2011

Thanks Tom, I agree with you . Nothing is forever anyway and if I took the engine off for something would put another back so not worried about paint. Just want to do it right. I tend to forget the search engine at the top. What happens I get reading all the other posts in here and dreaming of what I am going to do next and forget my original intent, such a info packed little site. Getting shirt sleeve weather in Ga. as they say ,,,,, love it. gphil

earl.k · Feb 19, 2011

i used a layer of tube and rapped it in tape.lol but mostly for my paint. also i have a shift kit, so my back is mounted on with two u clamps. and i have a sbp front mount. also a u clamp. so i could and did tighten them down good and solid. when i took my bike apart this winter. there where dents in my frame from my clamps. but all in all the paint was still good.

http://motorbicycling.com/members/earl-k-albums.html

bairdco · Feb 20, 2011

i worked on a guy's bike recently, and he had rubber cut from an innertube under his mounts. it didn't seem to be a problem, but it was still pretty fresh, maybe on there for a month or so.

by now, he didn't care about scratching his paint anymore, so i took them off and mounted it solid.

the rubber was already ripped around the "pinch" points, but the best thing, was when i peeled the rubber off, the paint came with it.

so if he ever takes his motor off, he's gonna have two nice little stripes on his bike.

oh, and it was a factory paint on an electra.

i mount all mine solid. they don't ever come loose, they don't vibrate, and they don't break bolts.

Venice Motor Bikes · Feb 20, 2011

I always advise that you mount the engine solid to the frame without any rubber.
There are some who claim to have had success with using it, but they're a very small group!

earl.k · Feb 20, 2011

Venice Motor Bikes said:
I always advise that you mount the engine solid to the frame without any rubber.
There are some who claim to have had success with using it, but they're a very small group!

yes we are a small group.lol but what works, works. and i have never broke a mounting bolt. and my motor has never come loose at all. in fact, i had to kick it a few times(with my foot) to get it out of my frame after removing my mounting hardware. but also. i DO NOT use stock mounting bolts. heavy u clamps for me.

Venice Motor Bikes · Feb 20, 2011

earl.k said:
yes we are a small group.lol but what works, works. and i have never broke a mounting bolt. and my motor has never come loose at all. in fact, i had to kick it a few times(with my foot) to get it out of my frame after removing my mounting hardware. but also. i DO NOT use stock mounting bolts. heavy u clamps for me.

It's a proven fact here that there are way more people who've had problems with rubber mounts than those who have solid mounted their engines...

I've personally built 100's of bikes & have tried every way in the book to mount a engine in a bike; the best way i've found is to mount it as solid as possible to the frame without any rubber isolators. What works, works!

earl.k · Feb 20, 2011

Venice Motor Bikes said:
It's a proven fact here that there are way more people who've had problems with rubber mounts than those who have solid mounted their engines...

I've personally built 100's of bikes & have tried every way in the book to mount a engine in a bike; the best way i've found is to mount it as solid as possible to the frame without any rubber isolators. What works, works!

im not saying that it cant cause problems for some people. every build is different. im saying. i ride dirt roads, hills and off road alot here in PA. i use a layer of tube raped in tape under all points of contact. so as im installing i dont ding my paint.( it will damage it some anyway in long run) and i Never had my motor move at all. not even my first build with all stock mounts. if i would not have used a brand new $400 bike to motorize. i would not have used any rubber.

but i did and it worked fine.(for me) and now i have a bigger u clamp in the front. and two holding my shift kit on. my front mount is not even bolted down right now. and i cant move my motor even when i try. and i have tried.

gphil · Feb 21, 2011

Appears solid as can be has won the mounting question. I would want it to be firm in place etc. I was thinking the rubber might soak some of the engine vibs but being tight I like. some of these after market so to speak mounts, how you guys like them. I have read to get new bolts and so on and will do if needed. Over tightening any bolt is not good. Anyway thanks heaps for the info. gphil

Bikeguy Joe · Feb 21, 2011

I have used lead sheet with success. Other than that, I'd say if you have to rubber mount, use some really hard rubber. I solid mounted all but two I've done, and those two used the above mentioned lead sheet.

earl.k · Feb 21, 2011

gphil said:
Appears solid as can be has won the mounting question. I would want it to be firm in place etc. I was thinking the rubber might soak some of the engine vibs but being tight I like. some of these after market so to speak mounts, how you guys like them. I have read to get new bolts and so on and will do if needed. Over tightening any bolt is not good. Anyway thanks heaps for the info. gphil

i dont use stock mounting bolts anymore. they are cheep to replace and i think its worth it. mostly because at least one is always bent when i get a new kit.
i got the SBP front mounting unit. if it will fit your build, id say its a good buy. or better yet, the $10 hardware kit from sick bike parts is cheep. and comes with nicer front and back mounting studs. also intake/exhaust studs and good hex head hardware.
or you could just go to the hardware store and find new studs and such. well whatever you do, good luck!

2door · Feb 21, 2011

This debate will always be here. There are those who will swear that their rubber mounts work and those who will always disagree.

Use what works for you. If you've soft mounted an engine or engines and have had success then by all means continue doing it that way.
What Venice and I are saying is that the majority of those who have tried it have experienced problems. Mechanical common sense comes into play here too. If you understand what can happen and make provisions for it, then soft mounts might work for you but there are those who will simply put rubber in the mounts without regard to the fasteners used, alignment and vibration issues who will suffer the consequences.

I repeat; use what works for you. This goes for every aspect of building a motorized bicycle. There'll always be differences of opinion and engine mounts are one of those items that people have been experimenting with since they first appeared.

The thing to keep in mind is this fact: Soft mounts do not eliminate vibrations or their source but only serve to distribute them to different areas of the bike/engine assembly.
Tom

earl.k · Feb 21, 2011

2door said:
This debate will always be here. There are those who will swear that their rubber mounts work and those who will always disagree.

Use what works for you. If you've soft mounted an engine or engines and have had success then by all means continue doing it that way.
What Venice and I are saying is that the majority of those who have tried it have experienced problems. Mechanical common sense comes into play here too. If you understand what can happen and make provisions for it, then soft mounts might work for you but there are those who will simply put rubber in the mounts without regard to the fasteners used, alignment and vibration issues who will suffer the consequences.

I repeat; use what works for you. This goes for every aspect of building a motorized bicycle. There'll always be differences of opinion and engine mounts are one of those items that people have been experimenting with since they first appeared.

The thing to keep in mind is this fact: Soft mounts do not eliminate vibrations or their source but only serve to distribute them to different areas of the bike/engine assembly.
Tom

well put, and to make things clear. i respect you, and all the people on this forums opinions. i also know that in most case that solid mounting is the way to go. and it makes sense why. and im not, in any way trying to say otherwise.

i just want people to know, it can be done. and if you do use rubber or whatever. you should use good hardware, not the stock junk.

the vibration is not effected to my knowing.(i cant feel a difference)
but again, not what im trying to do by adding a sliver of tube raped in tape. if i was trying reduce vibration id us some sort of suspension mount.

all in all, if you want to protect your paint when you are fitting your motor. a layer of tube held down with some tape will help. other then that, pointless. but it did work for keeping my paint looking nice. and any damage that is done by the mounts is under the rubber. out of site

Earl.

MaxPower · Feb 22, 2011

I think we can all agree that drilling a hole through the frame is about the worst thing you can do.

We can also agree the best way to mount is using manic mechanics mount. It looks like there is some rubber between the mount and the frame although the second picture has no rubber.

earl.k · Feb 22, 2011

MaxPower said:
I think we can all agree that drilling a hole through the frame is about the worst thing you can do.

We can also agree the best way to mount is using manic mechanics mount. It looks like there is some rubber between the mount and the frame although the second picture has no rubber.

that looks nice

dont know if i could use that because my down tube is really fat. i got the sbp front mount kit and still had to but a bigger u bolt for it.
question.. is it good to mount you motor flat? i know 4 strokes you should. but i dont see 2 stroke mounted flat like that ofter. just let me know ans thanx!

2door · Feb 22, 2011

Two strokes can be mounted in any position but chain clearance where it enters and leaves the engine and carburetor level are considerations. The engine doesn't care how it is mounted.
Tom

biknut · Feb 22, 2011

This is how I mounted mine and so far in 500 miles I've been very happy with it. Although I feel it reduces vibration, the main advantage is hockey pucks are easy to work with and make it easy to adjust the size of your mount to accommodate different size frames.

earl.k · Feb 22, 2011

2door said:
Two strokes can be mounted in any position but chain clearance where it enters and leaves the engine and carburetor level are considerations. The engine doesn't care how it is mounted.
Tom

thanks, that will be useful to know for later builds. also another question if i may.. what angle is best to have the carb mounted?

oldtimer54 · Feb 22, 2011

Keep the carb as level as you can.

To "rubber" or not

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