Motor mount; Clamp vs Welding

B

Big Bill

New Member
I am starting a new build so I need to decide weather to weld or clamp the
motor mounts to the frame , My Schwinn lasted about 5K miles
before the frame broke right above the weld the people who have seen
the frame said it looks like it got to hot when it was welded.

The new frame is a Dyno Glide using a jackshaft dive system that looks like
AGKs set up ( I made all the machined parts and bought the gears and clutch from AGK ). The cylinder will be standing up .

Thanks for the help Bill
 
Welding makes for a much easier and more stable mounting, however the problem is that you need to make absolutely sure the motor mount is where you want it and positioned level before you weld it, or you're kinda screwed. I thought about welding my motor mount, but in the end opted to clamp. I fashioned a 3rd motor mount out of a kit tensioner bracket. I put it in a vise and hit it with a hammer to bend it to the angle I wanted, bolted one end to my frame and the other end to my jackshaft. I also had to cut shims for the motor mount clamps because I have a skinny frame. Cut the shims out of an already damaged bike frame. But if you can position the motor mount properly before welding, that seems to be the way to go.
 
I prefer to make steel mounts to bolt the engines on whenever possible! ;)

Every now & then a frame will crack right beside the new weld from the engines vibrations. :(
 
Majority of bike frames are thin (16g-18g) maybe less. Any undercut caused by welding not only makes a thin piece of metal thinner but also creates a point in the metal. I forgot technical term. Think of it this way, unfold a paper clip and in the center create a notch or indentation, now grab both sides of said paper clip and bend back and forth. It'll break where the notch was. Same thing will happen on your frame. Can it be welded? Sure. I'd go with a clamping method of some kind though unless ya have a heavy walled (thick tubing) frame. Just my 2cents
 
Welding can weaken an already built production frame. If you're building a frame from the ground up, by all means incorporate the engine mount as part of the frame......you'ld be mad if ya didn't.

Clamping works just fine and can be as strong, if not stronger. Here's the way I did mine in a Dyno-Glide frame with the engine mounted up-right as you are going to do.......











Just a little food for thought for ya.
 
Scott's engine mounts are as solid as you're ever gonna get! :eek:

Jeff (CCC) also makes really hard core engine mounts for 4-strokes. (^)
 
Dont have a pic ,but they also make great tank mounts if u use two pairs back to back. Put a reg bolt thru and use a strip of metal to reach out to the tank bolts, rock solid!
 
Thanks for the replies guys.

Well it looks like I will be clamping the motor in the frame.
I found Scott-o's and CCC's builds the other day and all I can say
is WOW!! nice job. I will start a build tread this week end.

Thanks again Bill
 
Here's another alternative that I came up with... I welded some 1/2 pipes to the ends of a kit 4-stroke mount to make a super solid engine mount for a 99cc Predator engine on a aluminum Felt frame.

The engine is already rock solid before even securing it to the frame, & the design of the two 1/2 pipes helps protect the aluminum frame from damage from the engine vibrations! (^)
 

Attachments

  • image-1650030240.jpg
    image-1650030240.jpg
    420.3 KB · Views: 1,511
  • image-378309523.jpg
    image-378309523.jpg
    406.6 KB · Views: 804
  • image-3947455927.jpg
    image-3947455927.jpg
    391.9 KB · Views: 426
Last edited:
Venice Motor Bikes said:
Here's another alternative that I came up with... I welded some 1/2 pipes to the ends of a kit 4-stroke mount to make a super solid engine mount for a 99cc Predator engine on a aluminum Felt frame.

The engine is already rock solid before even securing it to the frame, & the design of the two 1/2 pipes helps protect the aluminum frame from damage from the engine vibrations! (^)
Click to expand...

I like it Norm, very nice and the engine sits in the slanted position (^) Funny cuz I'm doing something similar for one of my sons bikes using the 79cc HF.

.wee.
 
Yea i like that ,all the offset one might need is all in the plate vs in the mount to the bike. Ive been trying to do something sim. To fit a grubee to a felt slater hummm...
 
Venice Bikes Nice Job !!

Now that has got to be one strong Mount
It looks like you can use a few hose clamps and let it rip.
I just picked up Lincoln 140 HD welder a few months, but my welding
skills are still a little rough. Your mount is giving me some good
idea's.

Thanks Bill
 
You must log in or register to reply here.
Back
Top