So i went for a ride today with my friend he has a speedfight 2 50cc, its very rapid its got a technigas exhaust and lighter rollers he was getting 60mph downhill thats right of the clock but i struggle to get 55 also his acceleration is better too, i know the speed fights a way better bike there must be something i can do to keep up, im going to have about £150 free in 2 weeks, and i really want to convert to a 70cc, baring in mind i need it for college 20 miles a day so reliability is a key factor, i know £150 isnt enough but i could start buying the parts do they do exhausts that i can use on my 50 that will also give a 70 its full potential? also unsure on what rollers i would need and up-jetting? Cylinder Polini 70cc Sport 19mm carb Lighter rollers Up-jet needed? Exhaust Thanks
well, to be honest the biggest power increase for changing 1 thing will come from fitting a 70cc cyl kit when you fit a 70 kit, you are increasing the size of the engine, so you can expect an increase in power everywhere...more torque and more top end power when you fit a sports pipe onto a 50cc you are moving the power further up the rev band, which means less torque and throttle response everywhere else, which is why you have to fit lighter rollers and stiffer clutch springs, so the revs dont dip down ever into the area of no power... so the 1st thing i would do is fit a 70 kit, even if you retain the standard (derestricted of course) exhaust. Then as and when money becomes available you can add to the kit, feeling the exta power in stages
Im sure its fully de-restricted does 50mph and i didnt know a 70 kit would run on a 50cc exhaust, and would i need to upjet the standard carb as its small? and rollers Thanks dave
something like a polini/malossi sport 70 kit will run ok on the std 50cc exhaust and carb... dont be surprised if it actually goes faster than 50's with a pipe
You meen Dont be surprised if its faster than most standard 50cc's with just a pipe? like i said i would need one that works for 50cc and 70cc for when i upgrade, a exhaust seems like one of the first things to get, but as you recommend a cylinder first i have two choices im still a bit confused with it all, i meen i know what everything is rollers/jets/carbs etc but just dont know the sized and stuff like my standard roller size and jet size, do i fit lighter rollers or heavier with a new exhaust, are clutch springs a must with a new exhaust my friend didnt touch his on his speedfight Anyway I appreciate your help as always and yes i have read through the tuning guides im not just asking you to tell me everything Thanks!
No what he means is a 70cc kit with a stock exhaust will probably be quicker than a 50cc with a sports exhaust. In actual fact it's a complete pain in the arse tuning part by part as every single time you fit something you have to redo the setup or at least check it. If you search and read through from the oldest posts on the site you should quite easily find all the basic info you are after.
Your right i should just get the exhaust and leave it boxed until i get the cylinder/carb/jetbox/rollers then do a complete convert from 50cc to 70cc when all parts are together thanks lads for your help
