Piaggio zip 4T too slow?

stick a derestricted cdi in if you can get one for it. also pop that jet in see if it makes a change to and check those valve gaps

 

Ordered a coil,will try it at weekend then the jet.Only other thing I can think of is the stator pick up but we will see.

 

i would pop the jet in first see if that changes anything, the nature of the uneven revs could be fueling. even if its not its one less job to do and sets the daughter up for a little extra top speed.

one other thing could be the autochoke ( if fitted) on the carb, they can give up the goat and cause hard starting or uneven revs and bogging down. easy to check to, just unplug it from carb and bike, hook it direct to the bikes battery and measure the plunger when cold, leave it like 3-5 mins on the battery power and measure again , the plunger should have moved. if theres no measurment change the chokes gone puff and wants replacing ( bout 14 quid ), or you could replace it with a manual choke leaver setup, or a cabled choke setup and cowboy the leaver on the bars or subframe near the airbox.

when you start up bike choke is engaged and only turns off once that plunger system has heated up and slipped down to shut of the choke port. if that choke stays open theres just to much air and the bike tends to stall out / bog down at higher rpms / or just refuses to start without any help from a squirt of easy start into the carb throat.

 

Starts every time easily with higher rpm for a cpl of minutes and the revs drop to a normal tickover so I think choke is working as it should.Im starting to think it's more electrical now as even standard jetting would have surely worked ok for when the bike was in use before? However,ill definitely change that jet on Sunday and try it,then look at cdi change and go from there.Thanks for the advice mate,I will get this thing sorted!

 

Right,so
New belt fitted
Original rollers clean and in good condition , restriction washer removed
Carb clean , new 78 main fitted
New plug and cap fitted
Replacement Ducati coil fitted

Still the same! Revs up on stand then they drop and then fluctuates.Same on the road and won't go over 20mph.

What next? Fuelling to carb? Stator? Not a clue now....

 

would cross out the carb fueling as its been jetted up to 78 as stated by the manufacture.

only thing is coming down in roller weight , one more thing did this problem start before you derestricted the cdi or after you cut the cdi.
two things would be a second hand cdi thats not been derestricted and a drop down in rollers weigh to get those revs up higher. but more so the cdi a cheap second hand one so its not costing an arm and leg for a new oem from a shop.

im stumped now to as you have covered all major points sources for problems and yet its still acting up.

 

Yeah was doing it when we picked it up,changed the cdi for an unrestricted one so I don't know.Thinking stator pick up breaking down?

 

could pop of the shroud and take a look at the pickup gapping. but i would check that timing mark on the magneto.

only other thing i can think of is its a timing thing, ie magneto lined up with the mark on casing, then checking that the cam gear is lined up to and the valves are set correct and opening at the right time. if they are out it could throw of timing causing speed/running issues or tapping/knocking from the valves.

the magneto must line up to the timing mark, but the cam timing chain sprocket must also be lined up, so both valves open and close at the set time.

 

Got hold of a good second hand stator and pick up coil.Got to ride it for the mot tomorrow so will get round to changing it when I get a chance.Looks like I'm stripping half the body away just to get to it Should have bought a 2T!

 

been a lot more fun for you if it was a 2t lol , maybe a little to raw for your daughter once you had finished tinkering lol.

would still check those valve gaps and the valve timing , read a few other forum posts else where and folks had same type of issue. they found valves gapping had to much/to little play and/or timing was not set just right. after time the problems got worse and worse to a point bike stuck at 20mph. reason was they never went back for service or just did not bother checking valve timing/spacing every 2000-3000km

 

what about this buddy,

keeping an eye out for a 2t zip thats for sale as a spare repair. drop the motor and looms etc , put the rest into storage for spare to the 4t.

now you have a 2t motor thats gonna give some very sweet power when you tinker and add your fathers mods to it, make it all spankey sweet ( drop a bore kit in, nice little pipe ) then when daughter hits that 17yr old age, transplant the 2t motor into the 4t tell dvla of the change and capacity mod and let her loose on one mean machine.
a mild street bore shes gonna be pushing close to like 8-9hp and with angear up kit pushing same speeds a stock 125 hits but its going to get there about 3x quicker

its a little project for you and a sweet gift for the young lady if she is still into scoots, maybe even throw in a nice pink or likes paint job while the motors getting transplanted