upping from 50cc to 70cc

[jacky230766]

hi ,just need some advice,i got a gilera runner 53 plate,it had a leo vince exhaust on when i bought it and a split in the manifold (found out weeks after buying,) we had a few issues with power up hills,so checked out rollers and changed to lighter 5.25grms bike was working great until back wheel needed changing and numpty doing the job(at a motorcycle) garage snapped studs off,they wanted to strip engine as couldn't get into fix(also wanted £45 quid and hour) to fix,cutting long story - nephew said he could do it,but found it had already been done sometime before very badly so suggested getting 70cc kit,i did,it's now fitted and running but i have loss of power when riding ,comes and goes like belts streched or something,and wont pull up hill at all, main jet is at 72 ,do i need to do anything esle or is it a belt/gear problem,sorry for it to be long ut need advise as i've practially rebuilt this bike since buying in april,

[Livefast123]

I'm afraid to say that it's not as easy as just getting a 70cc kit, bolting it on and then it working forever after.

You need to change the jets in the carb to match the new engines demand for fuel mixture, match the weight of the rollers to the rev range that the Leo Vince exhaust works in and then you'll possibly need to change the clutch springs to make sure that the clutch is engaging in the engines powerband.

I would try contacting the exhaust manufacturer for details of the rollers and clutch springs they advise and you could contact the 70cc kit manufacturer for details of jet sizes etc.

If you don't get the jetting right then the bike will never run right and will damage your engine.
____________________
Current ride - Yamaha MT-07

[jacky230766]

thank you for your advice ,yeah didnt think it was gonna be straight foreward,even though i've upped main jet to 72 felt it needs to be around the 85 mark the rollers were changed from standard 9grams to 5,25 grams and this worked great with the exhaust,until we found the split inlet manifold,bought an enki manifold and reed kit but manifold sat too low so had to resort to another run of the mill manifold,seeing as i didnt have the pulling problems that i've now got,untill kit was fitted,I thought about the gears etc,so probably needs springs doing will have to check up on that as i have no ideal what ones are needed,thank you again,

[Livefast123]

You could pay a visit to a scooter forum such as Scooter Shack. Most of the members on there tune their peds and will probably be able to tell you what jet sizes etc to use.
____________________
Current ride - Yamaha MT-07

[MattWadz]

What size Carburettor are you using? after i installed my 74cc Italkit on my aerox, i had to up the Carburettor to a 21mm from a standard 17.5.
____________________
Pitbike x2, Mini Moto x4, China Quad, 02' Suzuki AP50 > 03' MBK Nitro > 86' Suzuki GP100 > 02' Yamaha Jog R > 57' Honda Lead 100 > 95' Piaggio ZIP Rst 50 > 51' Suzuki TS50x > 83' Honda CB125TDE Twin > 51' Yamaha Aerox > 98' Kawasaki KX60 > 89' Yamaha DT50MX > 80's Honda QR50 > 05' CG clone > 125cc China Pitbike > 91' Honda MTX125 RW-L > 09' Peugeot Speedfight 2 LC LR > Lucky MX 140cc > Apache Tomahawk 50 Quad (current = 2010 Yamaha WR125R

[SpannerMonkey]