Too much vibration.

[Eddiesilverbullet]

I have a problem with my 2 stroke engine. I just installed a decent expansion chamber but it still vibrates like crazy causing nuts and bolts to come off. What can I do? And does anyone know of a repair shop in the orange county area? Please help
Thanks.

 

[Deleted member 12676]

ha! that's normal for this engine. It drove me crazy till I investigated the subject, did some calculations, and then drilled two holes into the crank wheels to balance it correctly.

 

[crassius]

first, if it is a pre-2012 motor (ebay sellers still have those for the cheap kits), then it does not have the balanced crank - these are the old bone-shaker motors we all had to deal with years ago

if it is a newer motor, then vibration can be caused by rubber motor mounts (real bad idea) or by a cracked frame

sometimes just moving the motor lower can help frame absorb vibration better

 

[Deleted member 12676]

even the new ones vibrate too much

 

[FurryOnTheInside]

ha! that's normal for this engine. It drove me crazy till I investigated the subject, did some calculations, and then drilled two holes into the crank wheels to balance it correctly.

I think you make it sound too simple! Removing the primary cog, splitting the case halves, removing the crank, drilling big holes in it, packing them with foam and JB Weld to keep the CC pressure, reassembling crank and case without knocking it out of true.... I read the (your) article and had a good think about it, and decided I will just get the piston holed and wrist pin opened out (when I find someone who has a drill press I can use), and fit a retarded CDI.

 

[45u]

Buy a bottle of thread lock or other brand and a bunch of nylock nuts!

 

[FurryOnTheInside]

Buy a bottle of thread lock or other brand and a bunch of nylock nuts!

Loctite 242? And 263 for the studs?

 

[45u]

If you are going to use in a high heat area makes sure you use a thread lock is hight heat. All the common thread locks you use heat to brake them lose. Read the card it comes on.

 

[Deleted member 12676]

loctite won't reduce your annoyance from the vibration.
I've taken motorcycle cranks out so this engine felt like I was a kid playing with a toy. nothing hard about it to me.
don't have to worry about filling the holes with JBweld because crankcase pressure is not critical for a low reving engine.

 

[Deleted member 12676]

How many of you all would rather suffer vibration (and nuts flying off) for hundreds of hours instead of working a couple hours to make the crank right?

ps- lightening the wrist pin is not enough