Aerox 50 2015 no power stage 6 exhaust

Help please!
My son has an Aerox r50 2015, I have changed the variator to a malossi multivar kit, re jetted the carb to a 68 with the standard air box and filter and fitted a stage 6 exhaust. It won’t go over 27mph! If I refit the stock exhaust it will do 48mph. Any advice would be great.

 

That's mighty weird. Has the pipe got something stuck in it?

 

Hi, there was a restriction washer in the stage 6 that I had to grind out. Could it be clutch spring or roller weights?

 

I don't see why if it does 48mph with the standard pipe? It's got to be something to do with the pipe surely ..

 

A lot of pipes are restricted in the end can too, so check that.

Process will be similar to this https://www.pedparts.co.uk/blog/yasuni-exhausts-how-to-derestrict

Roller weights effect how high the engine revs so if its revving too low for the pipes power band you will make less speed

 

That is really weird.
Maybe the jetting is waaaay off?

 

Hi, sorted pad out today.
I have changed the clutch springs to red Jasil springs https://www.pedparts.co.uk/product/4058/jasil-clutch-spring-set--piaggio-yamaha and changed the rollers for Malossi 4.7g
Bike is reaching 50+ and running well now