PIAGGIO ZIP SP - stage 6 pro replica exhaust NO POWER! help!

Hi i recently got a stage6 pro replica exhaust for my piaggio zip sp 50 "liquid cooled" and was told by the guys at pedparts to fit these parts to make the bike run right however i have done this and the bike runs but whenever i give it any throttle it has almost no power and struggles to get to 20MPH! and it tops out at 30MPH but it takes forever to get there.
The bike has had the variator washer removed as well as the brass plate from the bottom of the carb! so its derestricted this is what PEDPARTS sent me.

Any help is appreciated thanks.

Hi,

If it's being fitted to an other wise standard bike:

Rollers (4.8g): http://www.pedparts.co.uk/product/1283/19x155-motoforce-variator-rollers

Jet (68 with brass plate removed): http://www.pedparts.co.uk/product/709/single-6mm-dellorto-jets-genuine-dellorto

Clutch springs (medium from pack): http://www.pedparts.co.uk/product/150/polini-clutch-springs

Thanks.

Pedparts UK
Unit 6, Bristol Vale Trading Estate,
Hartcliffe Way,
Bristol. BS3 5RJ
0117 9667988

 

possible you have the restrictor still in the pipe and hence your not seeing a performance boost.

remove the exhaust . look into the manifold end of exhaust, you may see a cone that is welded in with a spot tack weld. this is a restrictor.
to remove this you will need a dremmel tool with a grinding bur tip, a thin wire to bend a hook into and stop the restricter from falling into pipe when it is freed and a screwdriver to maybe wiggle the retsrictor once the spot weld has been ground away to break free the restictor.

So if its got a restrictor in it needs removing, once done you want to sand back any high spots from the weld spot that was put in.
replace the exhaust and give scoot a start up, ( you may have to upjet or adjust your carb needle setting so you do not run lean at top end wot, you may also need to re-adjust idle carb screw due to the better breathing the pipe gives ).

could be possible if your pipes already derestricted that the CDI is holding you back and needs either swapping out or cutting to derestict that to.

the video is for an aerox but its the same restrictor in your pipe, here they show how they remove it

 

hi thanks for your response buddy i forgot to mention that the pipe is already derestricted and what not
i have upjetted from the 53 jet that was in the carb standard to the 68 jet i was told to get by pedparts as well as the 4.8 gram rollers and the green polini clutch springs.
the ped just doesn't have any torque behind it now i dont think the clutch is engaging im all new to this and its becoming very anoying as i can no longer make my own way to work im stumped!

 

50cc's even when derestricted dont make a lotta low end torque, thats why we have to have the motor in the high rpm range when towing away as thats where all our power is made, usually around 8000+ rpm onwards, and with your pipe more closer to 9000 rpm.

68 jet does sound a lot buddy coming from a 53 your more better trying a 60-65 jet i would say.
its hard to tell without being next to the bike and seeing/hearing it running up and pulling off.

is the motor reving up high before the clutch kicks in and you move off , i am sure the other folks will pop in and offer up some advice.

have a look at this thread buudy to its about a zip jet upgrade to

http://www.scootershack.co.uk/threads/piaggio-zip-power-issue.18516/

 

68 is the correct starting point with the standard carb, standard cylinder, brass plate removed, a sports pipe and standard airbox and air filter element-
you cannot go any lower than this without risking seizure, especially in winter- all setups are individual but with no other faults if you dyno that specific setup it will always end up between 68 and 70 main jet- approx 2 sizes larger in the winter when the air is colder
this is a graph for Aerox, but Piaggio is always identical with the brass plate removed (62 if the plate is still in place)


the most common cause for that setup not running correctly with those symptoms is almost always either variator or air leaks (air box problems)
The airbox has to seal perfectly with all the screws present and all threads good. The cable-tie must be in place where the air filter throat connects to the carb and the filter element must be standard or twin layer if aftermarket and must be fitted correctly as shown...


also the inlet manifold must be good (no splits or other leaks)
This covers 90% of the problems we see in the above example.

Where the exhaust is a Stage6 pro rep with standard cylinder kit the variator has to be setup carefully sometimes also. The S6 pipe is revvy and about the highest tune which will run well on a standard cylinder which will quickly highlight any problems with a poor or worn standard variator which is unable to hold the revs consistently enough within the new required (quite narrow) power range. People fitting this pipe often swap the variator out for a Stage6 which is designed to match the pipe range but a standard one will work if it is in good condition and there are no other problems with the bike-

 

peak power using the stage 6 pro rep is 9200 to around 9850 rpm taken from pedparts site here ( http://www.pedparts.co.uk/c/asset/sports-pipe-blog/50cc.png ) as one can see this is a standard zip 50cc and been jetted to match the pipe and cylinder , would be nice if the jet size was mentioned with these dyno readouts. does not say but i would have said thats also with a stock variator on that dyno sheet ?

most would swap out to a malossi multivar 2000 more than the stage 6 as it comes with contrast spring to match the variator and gives a better ramp curve compared to stock variators allowing for better shift. ( maybe cheaper than the s6 variator upgrade to, most will air on the cheaper side, a pipe is seen but the variator is not )

problem is the stage 6 is very short on its powerband spread say compared with a technigas trek the trek has a peak between 8000-9000 where the S6PR is peaking way above that at 9200 to near on 10k rpm . even the Leo TT has a lower rpm need but peaks way beyond the S6RP pipe ( 6.2hp on the s6rp and around 6.5 on the leo tt but a good 1000rpm more early) and both the TT and the S6PR have somewhat tight powerspread making variator tuning a lot more harder and less forgiving on mistakes due to weight ( i know this personaly from running a TT and having the same exact rubbish lowend pickup )



now the young chap has no power at bottom end 0-20 is dire and 20-30 is tortoise slow yet he is running green clutch springs and 4.8g rollers , that should have the varaitor light on weight giving a large rpm increase ? green springs are what 2k over stock and maybe they just open out to late once power has peaked and started to drop away ? the 4.8g and green spring setup seems to me to be more aired at a 70cc kitted bike that a stock 50cc derestriction ( sport pipe slight rejet of around 10% and a set of lighter rollers usually 6g are thrown into the meld as a go between starting point , if customer is unhappy then it would be something like a white malossi contra and a set of blue 30% over stock clutch springs for that snap of the lights ?)

I would leave the 68 jet in, reset the rear clutch to stock springs and pop in 5-6g rollers see what the base is like from there then chop the rear clutch springs to the greens and see what the change is. i think those green springs are to heavy and he may well find the stock springs give a better outcome but thats just my guess ? then if unhappy with the low end take off lower the variator weights by .5g or 1g

 

ok, some good points here

"would be nice if the jet size was mentioned with these dyno readouts."

can't really be done unfortunately, there are too many problems with people copying the jetting sizes with slightly different setups (say an open air filter instead of an airbox or a non standard carb) and then of course we get the blame if the engine seizes even although they did not have the same setup

"does not say but i would have said thats also with a stock variator on that dyno sheet ?"

to get a power curve like in the graph you linked to you can't use a variator because you need a clean sweep through the rev range, so for that graph we would have replaced the transmission with a fixed gear system which uses a toothed belt and sprockets (like a car cambelt) which replaces the variator - this makes the ped run like a geared bike for testing

the problem with the narrow powerband pipes is that most variators (especially when worn) require that you develop a reasonable amount of power to pull through from the point when the variator first engages the belt (when you mash the throttle from still) to the (peak power) engine rpm you want it to be operating at.
The Stage6 sport pro variator excels at this (narrow band engine setups) because the aggressive ramping allows the engine to spool up almost immediately to a high peak power rpm with very little power at lower revs required to do this.
In contrast the equivalent Malossi/ Polini etc. are designed to be happy running on stock bikes and normally all their entry level variators come with rollers suitable for standard exhaust. The S6 variator in contrast comes out the box with rollers set to run at the peak rpm of the pro rep pipe. The downside of the Stage6 one is you could not take it out the box and fit it to a standard cylinder and pipe as easily as you could the Malossi which is more of an 'all rounder'

with the exception of transmission setup there are 2 things that come up again and again where bikes are booked in for 'tortoise pull away' problems which are really simple checks, the first is airbox problems as described previously, usually where the filter has been pushed in as in the photo or airbox scews are missing (this massively throws the mixture), also simply where the rear tyre is not pumped up properly- this can massively affects the bikes ability to pull through to peak power with a narrow powerband on a stock cylinder
http://www.pedparts.co.uk/blog/effect-of-moped-tyre-pressures-on-performance

 

hi guys thanks for both your input so far its very much appreciated! i will be working on the bike hopefully tomorrow as its my only day off in the last 2 weeks :/ and i will post a video of the bike ruining and going up and down the street before i start changing parts around hopefully the video can give you guys a little more insight on what the problem might be! and thanks again guys for taking the time out of your days to lend me a hand.