Baja with predator-Vibrations

[BBQJOE]

Everything is tight. No broken welds or cracks in the frame.
The engine has probably 200 hours on it, and many miles without any major mods, except straight pipe.

For awhile there has been a vibration.
It doesn't do it under acceleration. It doesn't do it when coasting, but does it somewhere in the middle.
The vibration is all over the bike, and goes right into the front end vibrating even the handlebars.

Valve clearance is good.
Fuel is good. Chain is properly tensioned. Running a torque converter. Belt is good. Weights are worn, but still ok, and the springs appear fine.

The engine isn't near as peppey as when new, but still gets along.

Thoughts?

 

[Raskin]

Wassup! Long time no here.. Grab the pto and see if any play ...take gearcover off and check if rod cap bolts loose..otherwise wait for a more sober opinion...:drinkup:

 

[creia]

It has been my experience that ALL of these China-made Predators vibrate- some more than others. It is the trade-off for being able to buy a brand new 6.5 HP engine for only $ 100.00. Even with the vibration, they are still one hell of a value.
Michael

 

[danford1]

Do you have an Aluminum flywheel too?
I remember when I replaced my stock flywheel with an aluminum one (because it is said they fly apart...)
I immediately noticed a lot more vibration. The light weight flywheels just allow more vibes to get out.
I thought building a scatter shield for the stock unit would have been a better option.
If it loosing power and vibrating more, it would probably be cheaper to just go buy a new one. Harbor Freight has them for $94.99 right now. It would probably cost more than that to rebuild yours...

Danford1

 

[Raskin]

hmmm..maybe wheel bearings shot!? grab the tire and frame and see if clunks?..anyways good luck

 

[Street Smart]

I`ve seen similar issues with a hemi pred I use on our pit bike. All stock engine , even the original muffler. I swapped out the flywheel with an OldMiniBikes arc billet one, same vibrations. I have a non-hemi pred on my 3 wheeler mini-bike and it doesn't seem to vibrate much at all.
Tim [MENTION=43506]trinik7597[/MENTION] mentioned swapping out some of the valve train would make it better.
Pretty sure my issue is engine related and comes and goes at different speeds/rpms.

 

[BBQJOE]

I'm certain mine is engine related.
I have a new 212 sitting on the shelf still in the box.
I'm just not wanting to break it out quite yet.

 

[BBQJOE]

I pulled everything of of the engine, and also swapped the flywheel.
It still shudders, most noticeable on deceleration.
It's also a bit noisy, but sounds more like the top end rather than the bottom.
It starts and idles just fine, but you can tell this vibration is also robbing power.

Do cranks wear out? There's no slop in the outer bearings.

What about the main bearing? Can it be worn out and the engine still run?

I'm just trying to diagnose before I pop the new engine in.
I'm also gonna check valve clearance again shortly.

There is zero exhaust smoke.


Edited to add:
Would a bent crankshaft do this?
Would it still run, and just how would one go about bending their crankshaft?