Bike vibrating furiously

[Baconator101]

So I lent my HT huffy cranbrook to a friend of mine after I had just built it to help me break it in. I had maybe 15 mins ride time on it, and it was running excellent... Anywho he Brings it back with a flat rear tire. Yuckkkkkkkkkkkk man, as you could imagine the headache of just having gotten the rear chains just right, now I gotta takem off again. Whatever, I let it sit for a week til I felt like getting back to it. So I get back to putting a new tube and rear tire back on. Take it round the block for a spin, somewhere at about half throttle the bike started viciously vibrating!!!! I slow down, still sitting on the bike, check the chains, tensioner, yadda yadda yadda, even look down on my motor to make sure it's still aligned correctly with the main tube, it is. So get back on pin it once or twice, still vibrating wildly like I've never felt before. I decide to go home. Get there safely and squat next to it to see if anything looks "off". I was riding around with only the 2 rear mount bolts properly secured, while only one front was barely hanging on cause the other nuts decided to fly off somewhere along the other person's ride. And I say "nuts" because I doubled up two on each bolt because i was out of lock-nuts. I was glad and shocked I made it home in one piece. So if you feel a sudden "suspect" vibration, please check your mount bolts.

 

[CrazyDan]

Loose mounts will do that.

 

[KCvale]

It's always a good idea to give your engine the 'shove test'.
Put one hand on your engine head, the other on the frame top bar above it, then try to shove your engine back and forth as hard as you can!

If it moves AT ALL, that is a fail giving you advance notice because if your arms can move that engine you can bet it can move itself.

Chances are your front motor mount does not fit your frame, most don't.
Some 2-stroke kits are shipping with a U-bolt front mount that comes with a flat piece of steel that goes against the round frame tube, and of course some claim you only need 1 bolt screwed through a hole in the frame for a front mount, but for any beach cruiser type build what you need is the right sized muffler clamp.

That gives you a 360 grip on the frame, and a flat place to put a piece of metal between your engine mount bolts and the frame.

That is a Sick Bike Parts model but I also make my own connecting pieces, and muffler clamps are cheap.

If you want your engine in right and able to pass the 'shove test', mount the back of the engine dead tight and flush against the seat tube, don't even worry about the carb level, then dick with the front mount using the 'muffler clamp' until it's mounted 'shove test' right.

 

[Baconator101]

Loose mounts will do that.

Never again will I let somebody use a "new build" Before I break it in and really get to know the bike myself. I guess a proper visual inspection would have avoided this...

 

[Baconator101]

T

It's always a good idea to give your engine the 'shove test'.
Put one hand on your engine head, the other on the frame top bar above it, then try to shove your engine back and forth as hard as you can!

If it moves AT ALL, that is a fail giving you advance notice because if your arms can move that engine you can bet it can move itself.

Chances are your front motor mount does not fit your frame, most don't.
Some 2-stroke kits are shipping with a U-bolt front mount that comes with a flat piece of steel that goes against the round frame tube, and of course some claim you only need 1 bolt screwed through a hole in the frame for a front mount, but for any beach cruiser type build what you need is the right sized muffler clamp.

That gives you a 360 grip on the frame, and a flat place to put a piece of metal between your engine mount bolts and the frame.

That is a Sick Bike Parts model but I also make my own connecting pieces, and muffler clamps are cheap.

If you want your engine in right and able to pass the 'shove test', mount the back of the engine dead tight and flush against the seat tube, don't even worry about the carb level, then dick with the front mount using the 'muffler clamp' until it's mounted 'shove test' right.

Thanks KCvale, I will have to look more into the muffler clamp application. And about the the shove test , I find myself pulling and shoving that thing all time, I didn't realize it was a common test for every 2 stroke builder haha, perhaps those muffler clamps will help.

 

[Frankenstein]

Half the world's problems are solved by clamping the s**t out of something, the other half are solved with a hammer beating the s**t out of something till it's loose again. Duct tape and wd-40 are some of the intermediate stages between the two.

The key is knowing which one to use and when. With the happy time motor it's best to expect a healthy dose from both sides of the spectrum. Your milage may vary, but the pain will all be the same.

Good luck, wear your damn helmet and have fun!

 

[Baconator101]

Half the world's problems are solved by clamping the sh*t out of something, the other half are solved with a hammer beating the sh*t out of something till it's loose again. Duct tape and wd-40 are some of the intermediate stages between the two.

The key is knowing which one to use and when. With the happy time motor it's best to expect a healthy dose from both sides of the spectrum. Your milage may vary, but the pain will all be the same.

Good luck, wear your damn helmet and have fun!

You speak truths!!! Especially about the pain. As long as it's only frustration and not physical pain, I'm in!

 

[Frankenstein]

You speak truths!!! Especially about the pain. As long as it's only frustration and not physical pain, I'm in!

I'd rather spend more time riding and crashing than sitting and fixing...

 

[CrazyDan]

Ever since I went four stroke most of my time is spent riding daily having fun and very little crashing and having to fix stuff.

 

[KCvale]

Ever since I went four stroke most of my time is spent riding daily having fun and very little crashing and having to fix stuff.

That is exactly why I primarily built 4-stroke shifters now.

No gas mix hassle, pedal starting, leaks and maintenance issues...
Give it a pull or two and off you go with an automatic clutch and gears so you can jump into traffic or climb a steep hill, and then haul ass on the flats ALL being vibration free.

If you have a 2-stroke and want to get some of the vibration out of your hands I suggest BMX type foam hand grips.

I use them on most every build regardless of engine/motor type simply because I just can't stand the hard plastic kit grips.

You can cut the grip off your throttle barrel grip and 'massage' a form grip over it with a little soapy water.

That is a cheap (<$10) thing you can do to make your ride more enjoyable, on my builds it's a standard feature.