.

.

What scooter ?

MARSH said:

What scooter ?

oh f... my bad. Aprilia sr50r. I will edit first post.

Hmmm... Water pump if it's LC?

Let me tell you straight away its your crankshaft, i guarantee you 100% its the crankshaft either change it or get it off and get it to be recentered if not too much off.

Your engine mountings might be seized solid, my SR 125 had the same symptoms, extreme vibration through the bars on anything between 10 and 90% throttle but not below or above.

Unfortunately, they didn't grease them when they came out of the factory even though it's a 5 second job.

Well if not the crankshaft it can be the CVT but you eliminated that, so next is the engine buffers or how u call them but i dont think so, they wouldnt cause that big of a vibration from experience(i drove a sr with that problem), i dont know what crankshaft you have but usually its always in the midrange and on full throttle you dont really feel them.

If you strip it down you will need 4 O rings, 4 engine mounting bushes (they're like white cups) and between that in the mount there are two metal bars, one of them will need a clean up and the other will likely be corroded within and inch of its life. Ultimate parts stock all of the items, should you need them. I'm unsure whether or not the 50 has silent blocks but if so make sure they're not worn too, unlikely that it would cause such specific symptoms if it was the silent blocks though.

Malossi Tom 172 said:

If you strip it down you will need 4 O rings, 4 engine mounting bushes (they're like white cups) and between that in the mount there are two metal bars, one of them will need a clean up and the other will likely be corroded within and inch of its life. Ultimate parts stock all of the items, should you need them. I'm unsure whether or not the 50 has silent blocks but if so make sure they're not worn too, unlikely that it would cause such specific symptoms if it was the silent blocks though.

The 50 cc bikes don't have a silent block

Cant you put it on a stand and rev the engine and possibly feel from what area the vibration comes from? Isnt any issue with the crankshaft? "Edit Sry. I missed the other posts suspecting the crank" get back when you know more

Just to throw one out there.......check the condition of the front tyre, not unknown to have a bump in the tread pattern or not sitting right on the bead

Stevep said:

Just to throw one out there.......check the condition of the front tyre, not unknown to have a bump in the tread pattern or not sitting right on the bead

Both tyres are brand new

I dont believe that u cant use the bar with the 2fast exhaust they are not that stupid, im pretty sure u need the bar in the middle its a must no question there, this is just yikes how can u even put the engine on the frame without it .......

So you have all these parts and stuff then why dont u just swap exhaust and add the bar if u really wanna see if its that instead of trying other things.