Frame shaking @ specific RPM during Acceleration.

[Wyvern]

Ok, Phatmoto frame using stock jackshaft and a Predator 224.

I get bad vibration at a very specific point in the power band under load, it also did it with the stock engine, I mean the whole bike shakes like a paint mixer but is fairly smooth before or after even giving it the beans.

My thoughts are with the frame is going harmonic at probably 2100rpm.

Anyone run into this? how did you fix it? later clutch lockup?

 

[GW's Motorized]

Your clutch might be shaking

 

[Wyvern]

Your clutch might be shaking

Did the same thing with the Hilliard clutch too.

It's not really a vibration, more of a shaking or hopping.

Ever change the stall on one of these clutches?

 

[GW's Motorized]

It's not really a vibration, more of a shaking or hohopping.

That's why I was thinking maybe your clutch isn't engaging all the way at that rpm. Do you know what rpm the clutch is supposed to fully ingage?

 

[Wyvern]

That's why I was thinking maybe your clutch isn't engaging all the way at that rpm. Do you know what rpm the clutch is supposed to fully ingage?

Lockup sounds like 2700 pretty early. I have no tach just yet.
This is happening below lockup.

 

[Sidewinder Jerry]

Are you doing gradual acceleration or rapid acceleration?

 

[Wyvern]

Are you doing gradual acceleration or rapid acceleration?

Gradual, but it does it regardless.

 

[Sidewinder Jerry]

What reduction ratio are you using?

 

[Wyvern]

What reduction ratio are you using?

Uh...Something.....

I think somewhere around 5.5:1? (18 to 32, and that drives a 12 to 44...I think.

 

[ImpulseRocket]

Uh...Something.....

That's my go-to ratio too!

Just to toss this out there, don't rule out the idea of it possibly being something speed related to the wheels and tires or maybe the jacshaft. If you cut the engine when that shake starts, does it immediately die with the engine?