vibration with drill vs. no drill front mount; 70cc

HI,

I have never drilled a frame BUT it seems to me that if an engine is directly bolted to the frame snugly it will transmit vibrations either way.....Only way to reduce vibrations is to add a vibration dampener of some sort between the engine and frame.

Hope the is helps you.

Andrew

I agree with Andrew...I don't think it makes a difference if you drill it or not. If it's going to vibrate, its going to vibrate no matter how it is mounted.

I drilled mine, put a piece of tire tread between mount and bike, very little vib, and it looks good.

Revo said:

I drilled mine, put a piece of tire tread between mount and bike, very little vib, and it looks good.

Click to expand...

i was going to suggest this - even on a non drilled mounting.


Not tire tread but a bit of inner tubbing. I've used this to dampen vibe on many many motorized applications ranging from a utility case mounting on an enduro to a fake mini gun on a motorcycle's handle bar (lol)

just be sure to torque it down and semi-perm locktite it

Your huffy was probably made of steel.
What is the moon dog frame made of ?
Use a sanding drum in a drill to enlarge the hole for your sprocket.

i drilled my cranbrook and it lasted about 10 miles the hole wore to about twice the diameter and the single bolt through the frame broke now am running a sbp adapter with inner tube and no problems

you could also try the front motoremount from sbp and maybe this will solve the no drill part

I drilled my frame like it said in my instructions for over sized down tube's. This was before I found the motorized forms. Now I know this is not a good idea as it can weeken the frame right where the motor mounts. My front case mount developed a nasty crack in it on the left side where the stud screws into the block. This has to be the weekest part of the case and it's right where it needs to be it's strongest. I fixed it by making a solid mount and replacing two of the case's screw's with grade #5 studs and bolting my new bracket to it on the left side. This is on a Schwinn Jag with a steel frame. New mount will also work as a torque strap. I had all the welding done for 20 dollors at a local sheet metal shop. Even if you don't use this method for your fix at least get the holes welded shut, it could save your life! Here are some Pic's this is a work in progress but I used this new bracket with it mounted through the frame and it worked fine (the crack in the case did't get any bigger after two tanks of gas) I can't fiqure how to post pic's and its late tonight I will try again tommrow. I can't fiqure out how to down size my files to post pic's or why it's asking me to. I've posted lots of pic's on other site's with no problem. Can some one explane how to do this.

Just a heads up...

If you are having a problem with a drill-through mount's hole becoming elongated and/or motor mounts are cracking/you're suffering from mount fastener sheer - odds are it's not the mounting technique it's the vibration.

Rubber mounts do not reduce engine vibration, they can actually increase it - they only reduce what you feel in the bike's frame. The engine itself will actually shake more as the vibration isn't as diffused through the frame and this can lead to premature failure of the mounting hardware and other problems.

Odds are if there's so much vibration that stuff is breaking it's one or both of these problems - your motor mounts are loose (not torqued down enough and/or "soft" mounted), and/or the rear sprocket is offset. Slowly spin the rear wheel, if the chain tightens and loosens even a lil it'll cause a "wrenching" of the engine to the drive side much like an impact hammer - this is particularly bad if the chain doesn't have enough slack in it. With soft mounts this effect is amplified.

Rubber mounting your motor is tempting as it can make for a more comfortable ride, but you may be sacrificing longevity for that comfort. I wouldn't try it at all with the kit-supplied "rag-joint" mounted rear sprocket as those will never be perfectly aligned.

I used some muffler clamps, exhaust couplers (tubes of steel) and some rubber hose that fit around my frame. I slit the couplers and hose and put them both around my frame. Then used a muffler clamp around them both. If you don't used the coupler then the muffler clamp cuts into the hose too much for my liking. Then take a flat piece of metal (I used aluminium because it's easy to work with and cut.) the bolts from the engine mount to the flat piece of metal with nuts on both sides(for fine adjustments) and the muffler clamps to the same flat piece of metal with nuts on both sides.
That should give you a strudy mount with some vibration ruduction.

Hope this helps.

I like to weld my frount mount.H.D.

thats nice you run wires through the frame!

I also put a plug on the wire.Every wire is hidden.H.D.

very clean work doc ! here are some pics of motor mount i machined from chunk of aloy! no drilling !