Hi

I have an air cooled Speedfight 50.

I've just fitted a new Giannelli Extra Exhaust, Polini Variator and Kevlar Belt, 6.5g rollers and jetted the carb up from a 50 to 55.

Basically it will now only go 15mph tops yet it will reach maximum revs when on its stand!! I've tried all sorts - different roller weights, the original variator and belt back in but makes no difference. Something just isn't working right with the new exhaust.

Carb is clean, compression is fine. I'm running out of ideas. Would really appreciate some help.

Thanks

Mikey, September 2009

i had the same problem with my speedfight when i fitted leo vince exhaust, and 6 gram rollers and it wouldnt go any where i put 4.5 gram rollers in now its fine just put 4.5 or 5 gram rollers in it and it will run again.

martyn, October 2009

I read that Giannelli exhausts don't have a restrictor in them but elsewhere I read that, for countries with tight laws on scooters, the exhausts are imported with a restictor in them.

Can anybody who's dealt with a Giannelli exhaust confirm whether they come restricted? Thanks

Mikey, September 2009

Huh, if that's true then that will solve all my problems but... in 03-04 they changed the carb model on speedfights.

It used to be 72 like you just said but then it changed to a 50 or 52 and mine ran fine when it was completely standard with a size 50 jet.

I'm still going to try a much bigger size jet though cos I have little else to try now.

Mikey, September 2009

standard jet on unristricted carb is 72. your jet is way to small. thats your problem.put 72 in then . if needed go up to 76.

rayb, September 2009

Yeah, reaches max revs & back wheel spins like a good un. Then you take it out on the road and it only goes 15mph!!

I've tried adjusting the air / fuel intake in the carb but that hasn't made any difference either.

I rang the place where I bought the parts from and he said it was a transmission problem - said that 6.5g rollers were too heavy and I should try some 5g ones. I'm not convinced though - can't see how it would only go 15mph with 6.5g yet run normal with 5g ones!!

The standard jet was 50 which is the lowest of the low. I've read loads of tips and advice on tuning & 10% increase is correct from what I've read. However, I've seen alot of other people with performance exhausts and they've got jets ranging from size 60 to 70 so I've bought some more jets in this range. Will try these with the lighter rollers and see how I get on.

If this doesn't work then I really am stuck.

Tip to people wanting to spend a fortune making their 50cc faster - it's nothing but hassle and isn't guaranteed to go right. Put the money towards a 125cc!!

Mikey, September 2009

Hi, I would pop it all back to the original spec if you can and start over. When it gets to max revs on the stand is the back whell spinning? Try and rev it off the stand and not sitting on it. (be careful it does not scream off) I would suggest something around your belt.
One other thing is a 55 jet the right one did you check, I am sure you did but worth asking.
Good luck and repost if you have to.

BB, September 2009