Yamaha neos 70cc noise from drive belt area?

Hi there have a 99 Yamaha neos mods,

70cc polini kit
Standard carb jet 78
Leo Vince zxr exhaust
Polini high speed variator kit

After fitting 70cc kit it is alot more noiser when it's cold almost like crank bearing cracking noise.
Once it's warm it is ok but when u get going there is a metalicy noise from the gearbox/variator area, I have romoved the electric starter gear and disc, there is no diffrence noise is still there. Do the kits run alot noiser ?

Also would anyone recommend a bigger carb or gear up kit?

Cheers

No they should run completely smooth. Did you change the small end when you did your cylinder, I'd take the variator/stator off make sure you can't see anything obvious. Does it do it when the bike is stationary ? Or only when moving ? If it continues, I would pull the cases apart. I'd check your cylinder as well.

Jonny cheers for some other info, it only does it when driving at higher revs, never replace small end bearing a checked them and they were fine.

What do you mean by pulling case apart?

I have removed the stater ring and kept it out and noise is still there!
The rollers am using are 3 x 6.9 and 3 x 4.0g weights as they worked the best.
How hard is it to replace the crank bearing lr crank, i am mechanically minded being one as a living.

Cheers

If you're good with a spanner set it's a peace of piss to be honest. You shouldn't run mixed rollers due to it being uneven, Put the 6 on some scales devide the weight by 6 then buy some of those

I suspect that your problem is something to do with the mixed weights in your variator. adding your weights up and dividing them by 6 gives an average of aroung 5.5g. Your'e much better off having 6 x 5.5g weights which will produce an even force on the variator.

Good thinking but the strange thing is I have tryed 5.5g rollers and the engine struggles to get the revs up.

Would anyone recommend a bigger carb for 70cc kit ?

try lighter, what size carb do you have now ??

It's standard think it's a 12, lighter weights are have tryed 4.3 and 4.5, way to revy and early kickin

Where about do you live ? I'd get it setup on a dyno if you can.

Glasgow, it is quick but struggling to get it set up mint

Alan McC said:

It's standard think it's a 12, lighter weights are have tryed 4.3 and 4.5, way to revy and early kickin

put 5g's in and if you think about mixing weight ...do the science bit first there will be more weight on one side causing the crank not to be balanced and your rollers wont all kick in at the same time and may be causing the rattling before you split the cases run it with 5 or 5.5 gs in

fingers crossed itl sort it

I will give that ago, I have tryed 5.5 and they would not let the engine rev up!

Alan McC said:

I will give that ago, I have tryed 5.5 and they would not let the engine rev up!

5 or 4.7

Ok cheers mate

As for the carb go with a 17.5 it will really improve the performance.

Where abouts do you measure the carb, at airfilter end on inlet manifold and is it the internal or external diameter cheers

Alan McC said:

Where abouts do you measure the carb, at airfilter end on inlet manifold and is it the internal or external diameter cheers

Air filter end internal

The carb is a 17.5mm on the scooter the now, found what the noise was and it was the ht lead was hanging off which was making it noisy pushed it bak on, job done also ordered new roller which are the right size

What is next to do ?

Cheers

Have you upjetted since putting the 70 kit on and to get the best out of the pollini 70 kit you should gear up.

What gear up kit and how they to fit ? What advantages will that give ,


The carb is upjeted to suit modifications !

Cheers