Motor Mounts

[Lincoln78]

LOL I HAVE 2 Mounts, Its Just the Front one is broken, The bolts snapped off inside the motor, I was trying to show in the pic, them broken off, But Yes I do have a Front Mount, If you looks at the Pics it shows the Front Mount NOT on the bike, The Black Bike

 

[Lincoln78]

kinda looks like instead of spending all that money, you could have just added one extra rear mount block to the front with longer studs or bolts, but I usually just use the flat plate that comes with the kit

a bit of PVC in the rear mount is nice, but never rubber anywhere

....My Kit Didn't Come With a Flat Plate

 

[bairdco]

are those black blocks chunks of rubber? and that's what you paid $400 for?

rubber doesn't work. never has, never will. it's the number one cause of studs breaking.

you coulda saved a ton of money with a little research.

http://motorbicycling.com/showthread.php?t=25659

 

[crassius]

nice bike - I see you also know the trick of lowering the pedal chain guard to get the motor lower in the frame : )

 

[Lincoln78]

Yes them Are Black Blocks of Rubber, But They came with my Kit From A Site That Sponsors This page...So Anyways..The Metal Pieces are what cost a ton , and to have the holes drilled out 2 times cuz the bolts keep snapping, I LOVE that design you got, Would try it out myself!!

 

[2door]

You could do something simpler, and a whole lot cheaper. For what you spent on the machine work and those useless rubber things you could have paid a welder to fab up a front mount. It would have been far less money, and it would have worked.

Tom

 

[crassius]

yep, front mounts are often unique

back mount is the important one and works well if it is perpendicular to the frame post with a bit of PVC on the engine side, and dead tight

front mount is only to hold the engine straight & doesn't bear much of the force, so can be most anything you have laying around that will keep the engine from shifting left/right

 

[bairdco]

i disagree. the front mount is equally important, 'cause it stabalizes the engine.

the engine has a natural tendency to pull to the left because of the torque on the chain.

with a weak front mount it'll constantly shift to the side, which loosens the chain, de-rails it in some cases, and always messes up the chain alignment.

the next thing to go is the right rear motor mount stud as all the strain transfers to it.

as far as using pvc, is that to fill the gap or as a cushion?

newer motors have larger mounts for newer frames. i make.shims from old seatposts, or from a thin sheet of aluminum.

seems to me pvc would crack, wouldn't get the "bite" you need to clamp it down tight, and would eventually fail.

i've seen bikes with a small strip from an innertube in the mounts, thinking that will help bite down and save the paint.

everytime i've taken one off, the rubber is wasted, and usually takes the paint with it, since motor mounts like to collect dripped fuel and saturating the rubber. add some road grime and it disintegrates.

metal to metal, better bolts, and routine maintenance is the simple recipe for a problem-free mount.

 

[2door]

I couldn't agree more. Baird is right on the money here. Read it and heed it!

Tom

 

[bairdco]

thanks tom, i know we agree on motor mounts. i don't know why new guys still go through this problem. we've beat this horse to death.

as far as i can remember, besides my chain breaking, cracking the case and breaking my studs, i've only had one stud break on me.

it was on a race bike i finished the night before, used stock studs in the rear 'cause i didn't have the right size allen bolt, and the right side broke during practice.

since i use anti seize instead of loctite, i was able to get it out with a small screwdriver and was back on the track for the race.

then my piston seized...

 

[crassius]

still say back takes all the force, front just keeps it straight

 

[2door]

still say back takes all the force, front just keeps it straight

Point is, the front mount must be done right or it won't "keep it straight". Go cheap on the front mount and you'll have problems. The rear mount can not overcome the stress from the drive chain pulling the bike if the front mount isn't done correctly.

Look at it from an engineering point of view. The force applied to the engine mounts while under power will dictate that relying only on the seat post mount for stability the engine can/will torque to the left. If the front mount isn't substantial the engine will move resulting in a loose chain and the results won't be pretty. I promise.

Both front and rear mounts must be solid and secure. No way around it.

Tom

 

[crassius]

solid and secure are the ways to go, but if the back is just right, I could hold the front straight with one old, skinny, arthritic, finger - but then, I always do good work on both anyway

 

[Pedalson Of Anarchy]

There's the problem! Get rid of the rubber! It will not eliminate vibration but only transfer it to the mounts and fasteners. There is plenty to read here on that subject. It has been tried countless times and it does not work!

You might get away with it temporarily but eventually, somethings going to break. Guaranteed!

Start over. Mount the engine solid to the frame and go from there.

Tom

Well in my case it worked nothing has broken du the vibration since and especially I have no more feet and ass that warms me.