piaggio skipper 150 2t losing top speed

hi guys my skipper will lose power after 80kms, heaps of power and smooth acceleration till I get there but as soon as I get up to 80 odd I drops off suddenly like it's running out of fuel? or the belt is slipping, so far I have put on a technigas exaust and malossi multivar.
any advice much appreciated please

 

Try the std exhaust back on it. I wouldn't waste money on the mutivar, std works fine with a good roller set up.

 

cool will give it a shot, yeah I was recommended a multivar by the only scooter shop that does upgrades in nz and reckon I was up sold!

 

tried original exhaust and original variator, no change, have ordered a new belt and will strip carby down, it feels like the bike cuts off at 100 and will pick back up at 80kph.. so strange

 

Are you using std airbox ? Have a look at size of main jet, it should be a 82.5 ? I run between 84-86 here in the UK on a 150cc !

 

yeah I've got an 85 in there, cheers

 

Is it fuel injection or carb’? Similar symptoms to when the petcock isn’t feeding enough fuel through at high speed so carb’ effectively runs dry, loses power until sufficient fuel is supplied. Blow fuel lines through, check vacuum hoses and maybe get an upgraded fuel petcock. I don’t know your fuel delivery system on that ped though

 

Ped ? It's a 150 so it's a scooter !

 

Semantics, 150cc is just a grown up ped I apologise for hurting your pride, yes you have a scooter not a moped.

 

I had a "ped" at 16 in 81', A Honda ss 50, never have liked the word ped ! cheers.

 

Classic bikes, my mate had a fizzy but I made the mistake of waiting for my car licence, lesson learned, both my lads got scooters on their 16th birthdays. Soon had to learn how to repair them though

 

cheers man, it's a vaccum petcock, I pulled it and checked the filter which wasn't dirty and reinstalled it with new fuel lines, seems to taken care of the problem atm, have a new belt on order too! will get a few photos up soon cheers

 

new fuel line

 

and another moody pic haha

 

Hi .
sometimes it´s so simple as a tank cap with the breather hole blocked.
do you know where to get a shop manual ? i´m restoring one 125cc skipper