Piaggio zip 70cc problems!! PLEASE HELP

Hey, ive recently put athena 70cc big bore kit, 21mm tnt carb, gianelli exhaust and polini variator and i went out and bought box of jets between 60-80 and i was messing around with jets as 80 run almost perfect with open airfilter but i want to run with airbox, i was trying to find jet and went down to 60 and it runs almost perfect but still dies. 60 seems really small to me please help dont wanna seeze engine!

 

when does it die, high revs, low revs?

 

low revs mate

 

what was the stock size jet with the 21mm carb ? was their one fitted and suggested?

a larger carb uses a smaller jet as compared to a smaller carb so it might seem small, the only way to know is top check the plug after a full revs run and shut the engine off. With an open filter you need to upjet the other needles aswell but with the stock airbox you should only need to alter the main jet.

Have you adjust the idle? it could be that the needle on the throttle needs raising to open it a bit more when its at idle

 

The carb i bought didnt have a jet installed but came with jets 75,80,85,90,95,100,105 in packet. and there was no suggestions. ive adjusted the idle and its perfect. Its more when i ride down the road and go to turn for the corner so let go of revs brake and slowly dies.

 

hmm, i think you need to speak to someone with carb tuning knowlege, it could be you need a larger low end or idle jet. it could be that the needle is dropping too low and so is starving the engine. if you hold the throtle open a tiny bit does it stay running?

you may need to lower the throtle needle clip so it sits open more and then readjust the idle via the screw to suit.

 

Standard jet in carb is 56. i am trying to find out how much your supposed to increase jet size when putting big bore kit on, ive heard 2 sizes increase and also heard 10% increase which is 5 jet increase. What about exhaust? ive heard thats a 5% increase.

 

i was told 10% for pipe, to be honest i have fitted a jet thats around 12% bigger to my carb having only fitted a pipe and it runs fine. just dont run it lean haha

 

well then i must be running lean 60 jet when standard is 56? im running on 70cc kit, 21mm carb, race pipe :L so in theory i should be running around 62-64 jet?

 

it depends what they recomend when fitting a big bore kit. for just the pipe a 62 would seem the choice for me, however if you are meant to upjet by 10% again for the 70 kit you will want a 68 roughly.

however the stock jet you mention may be for the original carb? the 21mm you have will most certainly run different jetting to the stock carb so may be way off the mark

 

bigger carbs run on smaller jets so dont think much difference so if i work on a scale of 56 jet as standard, i need to find out if there is a increase in the bbk to procede to further work.

 

today i messed around with bike again and i put 64 jet in and run quite smooth untill around half thorttle it bogged so i backed off and ran ok so i thought it was needle so changed that to every notch and still doesnt work. Then i tried putting open air filter on and setting up and that was just a nightmare, when i put open air filter on the acceleration was reallly bad and hardly moved why?!?!?!

 

super lean

 

nope i had mates dad down today and he tuned my carb for me and i am currently running on 60 jet with needle on 2nd notch from top and runs alright but every now and again im lacking of power and he noticed a air bubble in fuel pipe feed and he said maybe thats problem is he right?

 

could be, i cant see any reason why you should have air bubbles in the lines fella, this will cause the lean effect.

when you say he tuned your carb, was this done on the bench or did you warm the bike up and give it a good full throttle run to check for bogging or spark plug colour

 

he warmed bike up mate and did spark check and is running nice and perfect. how can i get bubbles out of fuel like? shall i replace pipe cause got some pipe laying around spare. (pluss im still running piston in, and he said this can cause alot of bogging but should cut totally out)

 

would you say new fuel pipe would solve the problem and get rid of the air bubbles??

 

drain out the pipe,and just make sure the bike is filled up with petrol.. diferent pipe wont make a difference, you may just have run to low on petrol so it sucked in air.. could be a few things but new pipe really wont make a difference..

 

fuck thats exacly what i did! left lid off petrol tank and ran bike with hardly any petrol -.- im a fucking idiot. Thanks mate ill drain it tomorrow

 

ahaa think uve found your problem hope all goes well mate.. lets us know if theres any more problems