T5 disapointment

ive just bought another t5 it had a 152 kit on standard carb jetted with a 130 and a simo pipe also 21 clutch it ran lovely cruised at 70 75 top, but as you do ive just put a 172 kit on runs fine but after a 200 mile run in, ive dropped the running in jet down from a 132 to a 130 with a b3 atomiser and theres no performance increase apart from its very slightly torqueyer and top speed now seams to be 70 can anyone give any advice as im slightly disapointed my local shop isnt very helpful at all and you guys seam to have alot of experience thanks paul [:rotate:]


somebody in this forum like the 26, I think is adriannewamm, but maybe is somebody else, I personally find out it is not a real 26 but a 24 made larger to 25. I tried and it is ok but if you have a 24/24 it is not a change that will give you that much. Much much better try to get your carburation right.
Your head as been milled to work at 16? Are you sure? Who told you this really knows ? I think it is better trying to let an engine give its best at the less advanced timing possible so heat will be transfert to the exhaust gases and engine will run cooler. But of even more interest the gasses beeing higher in temperature will travel at higher speed and the effect of the exhaust expansion will be more evident. [:smokin:]


yes, you have to check the time with strobo.
No, for me, having tried both, it is not that much better if you have everything else standard , but the more you do the better became. [H]

thanks curare
i paid a visit to the scooter shop earlier to get it checked out by harry barlow the t5 tuner and apart from adjusting the airscrew to get it running better he thought it was spot on the timing is at 16 he said he had milled the head out so the timing can stay at 16 its still rough through midrange when your not thrashing it so im going to try the origonal atomiser b4 see how that goes if no good i will insist on retardng the timing.
checked plug and its perfect with 130 in yet another guy turned up with 172 kitted t5 with jl pipe and and he was running a 122 and that was dyno jetted wierd!!!
o the joy of owning a vespa


just checked my note book.
Polini 152 with 24/24 I got the right main (Simo pipe) 118-122
Malossi 172 with simo pipe 120-125.
To me it seems 130 too large. But you said 130 was working lovely with with 152… start going down and if not expirienced check always the spark. Start with the one you have(130), get on a right road where you can keep max rpm for 20sec, then turn off ignition key and pull clutch lever[:(]I think this procedure it is called in english plug chop). then check the plug. If it looks kind of black or wet it means you are rich and you can use smaller jet without beeing afraid of sizing. Then repet the operation until you get a brownish colour. Look down the ceramic not just on the most superficial part.


…was your ? about the plug chop procedure?

Have you changed the timming? 16 standerd and 14 malossi!
I think the polini is 18? not sure,but best to do with a strobe to be exact.
Also did you get the head opened to suit?


if you don’t get the time more o less right you can’t go for right jetting.

If as could be or not your case you are 2 degree more advanced the engine will run flat at high rpm and it will overheat.

You can get the timing right by feeling if you are experienced enough but you have to know your original timing. Then 1mm about from your original point it is about 1mm either advance or retard depending in wich way you turn the plate.
Of course strobo gives you the right spot . It is a fast way, and if you have not one I am sure you will find somebody or a professional that has one and the setting take about 15-20 min so they shouldn’t ask a lot of cash for it.


Hi there i have a t5 with malossi 172 kit scorpion pipe main jet is only 122 tryed 125 goes better with 122 had same jet with simmo pipe no problems


yes the main jet 122 or around it is what I would expect as I told you before. But have you tried to go slightly leaner let’s say 128?
Try, see how the engine respond, at least to know if it is the right way to go.
But before
as far as the time if I am not wrong, somebody in case please correct me,
should be 14 for a malossi 172.

If you don’t get the time right then everything else it is going to be a compromise to correct other fault.

im getting somewhere the bowl in the head hasn’t been milled out as much as the malossi spec giving it more compression aparantly this is why it needs bigger jets
i tried the b4 atomiser and it just slowed it down so i put the b3 back in i will try a 28 and see how i get on
yes timming is 14 mine is set at 16 i was told the head was milled to run at 16
it runs well now when you give it some its just a bit rough when your in traffic
i think im going to order a pm pipe this week and get it on the dyno would have liked a taffspeed but they have been out of stock for 3 months and won’t be having any for another 3.
or wait till march for vespadocs new one
have you had any experiance with the si 26 carbs or whats the best without moding the cases?

yes head was done i will try and get the timing done this week should it really be alot better even without expansion pipe or bigger carb ?

thanks very much guys its better than going to the scooter shop for advice i will get to the shop on wednesday and get a few jets and i will let you know how in get on.
i took it for a spin today and it pulls well prob till about 5000rpm then its pretty flat it does feel like its to rich but the plug looks nice and chocolate coloured not oily so i will get a 28 & 26 and see how it runs
is there any easy way to alter the timing as i haven’t got a strobe ive done it many times on cars and you just move it till the engine runs at its best???
just out of intrest what does curare mean?? i tried dropping jet on the 152 kit but it was to lean so stuck with 130 thanks for help dude [:look:] [:smokin:]