speedfight 2 help tuning for a noob

HI all. hoping someone can help me im completely new to all this and need some info.
ive had my 2008 speedfight 2 for a couple of weeks now and im loving it but it seems like it is having trouble accelerating at higher end, almost like its struggling for air or fuel. the ped had a gianelli exhaust on and previous has told me it has not been upjetted.
ive now been looking at a malossi 70cc kit
a pack of jets (need help with which ones)
a 17.5mm carb (again need help with which one)
what else would people reccomend for a reliable but reasonable speed ped!

any help massively appreciated

 

Hello josh and welcome to the scooter shack.
the ol speedy 2's , not bad a scoot either .

i would say if its not been upjetted thats your problem. the pipe is now allowing the gasses to escape more quicker and allow a little extra fuel charge in, but if your not upjetting to do this it can show as a boggy top end or even worse as an overheat problem .

is your speedy a liquid cooled model or the air cooled version ( the lc model had a handy dandy temp gauge to help show an overheat ).
most young folks have this thought that the 50cc engine will get them to like 60mph, truth is around 40-50 is the very most your going to see without doing some very hardcore tuning work ( and risk to hurting the engine more ).

fitting a 70cc kit and upjetting a 17.5mm carb is not an easy thing , no plug and play here your going to be rejetting a couple times to find the sweet spot, usually its a 10% - 15% more on the jet size. ( lets just say its a 68 jet in carb now and it runs rough, your going to be upjetting to around 78 on the jet size and adjusting the throttle slide needle for the 1/4 throttle to 3/4 throttle range ).

with the jet size your not going to know until you know what jet is installed in the carb , you would tend to throw on the kit then the new carb and run a plug chop ( ride it hard for a couple mins then turn engine off while hard on throttle so you can see the state of burn inside the cylinder) , the new carb will have a jet already installed then you look at that jet size and start higher up and drop down a jet size each time till the plug chops show a stable burn ( the spark plug colour will be a chocolate brown / tea stain brown look and means the burn is just right ).

with a 70cc kit fitted your still only going to get a certain speed before the gearing ratio is maxed out , dont get me wrong its gonna be a rapid scoot but only to a point , you may find top speed is only 55mph and that will be down to the variator and belt travel in the pulleys and the gear sizing in the wheels gearbox. to get a higher top end speed most owning 70cc kits will then look to upgrading the rear gearbox with a gear up kit adding a few more mph onto the top end.

Last but not least there are legalitys to having a 70cc kit installed, if your 16yr old its a big NO, if your 17yr old its fine but one must tell dvla the scooter has been upgraded in capacity, your scooter then no longer is a moped it becomes a motorcycle, your insurance will have to be told to keep you on the right side of the law to.


My advice would be to first get that slow top end buggness sorted out and maybe re-jet your carb to suit the pipe fitted maybe also look at the roller weights to tune the take off speed and top end a bit, then look at the implications of a 70cc kit , if your 16yr old you may be better off just waiting until your 17yr old and then going for a 125cc usuing that years wait to learn the art of road riding / control / and the laws of the road

 

hi mate thanks for the welcome!
im 22 so no issue in delcaring to dvla and insurance and things just rekindled my love for a scooter haha. i have a friend that is very good with tuning scooters so he will be there to help with fitting the new things so that part is fine. my speedfight is air cooled.
the bike had been stood for two years when i bought it so obviously some things are going to be clogged. i was thinking of just buying the new 17.5mm carb just because i know i am going to get the 70 kit soon anyway so instead of messing about changing jets on the old carb first then buying a new one and messing around again i might aswell just buy the new one whie i have the money too and set that one up. i know just buying a pack of jets and working through them to see which set up is best for that but how would i go about the rollers? would it need lighter rollers?

without going for a crazy set up just a nice nippy bike for now would you reccomend anything more than
70ss kit
17.5 carb
jets
rollers.
would this run okay while i saved for more parts like variator and belts and clutch springs etc

 

yes as for the parts selected its a nice place to start .

upgrading the stock carb to a 17.5mm could be the better option , my 17.5mm came with a 90 jet and i had to downsize to an 81 jet ( derestricted 50cc and trek pipe ) but now it runs sweet as a nut.

your also going to want to make sure the oiler pump is delivering the right amount of oil ( your scooter mate will be able to do this for you)

carb wise a delorto copy will be fine, when you get it just check the jet size first, also check the jet size in the old carb its a good starting point to know what it is. bolt on carb and give scoot a fire up see what its like if its a dog runner, then you need to come down a few sizes in jets, do this in steps of 1 size or 2 sizes lower each time till you find the sweet jet thats giving good throttle range but also leaving you slightly rich to ( always good to air on the side of a little rich fuel wise ).

Rollers, pop of that variator and have a gander at whats already installed, you may find they are like between 8g and 6g rollers , if they are fairly heavy you can drop a gram or two in weight see how that feels, or even stagger them, say 3x6 g and 3x7g . but see whats installed first then make the choice to go lighter and by how much

 

cheers mate youve been a massive help. gunna get on to it now and start having a look whats currently on it and then order some parts. i dont dare ride it until the problem is sorted as dont want to seize the engine!