Speedfight 2: Not Running Right With New Parts??

Hi guys

I've bought a 2002 Speedfight 2 50cc AC that was meant to be completely standard apart from a viper exhaust and the restrictor place removed from the variator.

I thought I would give it a service as from speaking to the previous owner I guest it hadn't had one in a while.

After taking the variator off I could see that it still had the standard 9 g rollers in there and they weren't in the best condition and while cleaning the carb I noticed that it still had the standard 72 jet in there even though it has an after market exhaust.

So I put in some 6.5g rollers to make pulling away s bit better , changed the jet to a 76 and replaced the belt.

After doing all this the scooter was revving really high but only going about 10mph (felt like it was stuck in 1st gear), so I thought I might have gone too light with the rollers so i fitted some 8.5g rollers but it didn't make any difference.

I then put the old belt back on and everything was A LOT better.
The only problems I'm having now is that its still revving a bit on the high side and only making about 40mph at a push.


I ask a few questions on another forum (before I found this one) and they said it could be the contra spring was too stiff so I fitted a white one and that didn't make a difference either.

The belt I bought said it was meant to fit my scooter and the marking on it say its size is 17.5 x 8.3 x 765 and from reading around the size seems to be correct but the belt that was on there says the size is 11 x 729 x 17.

The new belt does look quite a bit wider than the old one and does hang over the front pulley a bit.


Any ideas ?

 

Just looked a the thread and thought I would say sorry for making it so long....lol

 

One more thing.....

When i took the variator off there was this washer behind it:








Am i right in thinking i leave this one on as it seems like its there to stop the variator rubbing on the crank ?

 

Sounds like you got the wrong belt to me. And yeah, leave that washer

 

When I replaced my belt a couple of weeks ago the performance was down until the belt ran in it took a couple of hundred miles.

 

Thanks for all the replies

That's what i originally thought but its the only size belt that's listed for the speedfight 2, its also the size aj sutton show.

Its not just lacking performance with the new belt, the scooter hardly moves.

The only way i can get it to run a bit better is to fit the old belt with heavy rollers.

 

Ok. Mine was not that bad.

 

No probs

Look at how much slack the old belt has:




Compared to the new one:




And you can see how much wider the new belt is in this pic:

 

that old one is fucked. i wonder if the new one is too wide maybe?

 

That's really my confusion, if this new belt it the correct one for this scooter then what's stopping it from working?


I've even fitted a softer contra spring but that didn't make any difference :-(

 

I have a TKR2 that should have the same Euro 2 engine as your Speedfight 2. The new belt that I fitted to mine when I changed to a Polini variator is a Naraku one, sized at 765 x 17.5.

I'd say that the new belt is the right one and needs to bed in for a while to get best performance from it.

 

Like I said to bogey, its not a case of letting it bed in as the scooter hardly moves with the new belt

 

Check the rollers, they may have flat spots on them causing the variator not to work properly. If they have flat spots the bike bogs down badly.

 

All in my first post


Things I've tried changing (and in combinations) are:

Rollers = 6.5g , 8.5g and 9.0g.

Jet sizes = 72 , 74, 76 , 78 , 80.

Contra Spring = softer white one.

Belts = new and old.


The only combination I've managed to get it to run as goo as it is was with the old belt , 76 jet , white contra spring and either the 8.5 or 9.0 rollers.

But even with this combination the engine seems to be running a bit too fast for the power its delivering.

And I should be able to service it with the correct size belt....lol

 

It really sounds like a belt issue tbh. How many miles have you done with it.

 

I've not been able to put any miles on it because like I keep saying the scooter hardly even pulls away with the new belt

 

It was the rollers at fault when my TKR2 did this same thing.

Just thinking around the problem for a moment - was the variator shaft sleeve smooth and free of steps when you looked at it? If the variator gets hung up on a step worn in the sleeve, it won't engage properly.

 

No probs

I would sooner a load of wrong suggestions than no suggestions at all....lol

Yea it was all smooth , I even used a bit of wet n dry on where the rollers are just to make sure they run smooth.

 

Have you measured the belt? Also, pull the clutch pulleys apart so the belt sits lower betwwen them and is nice and loose over the front pullys, thats how I always do belts

 

Yeah I measured them with a digital calliper and they were exactly what they say on the label.

I actually thought that was the problem when I first changed it an the scooter felt like it was stuck in 1st gear as I only squeezed the clutch pully enough to to streach it over the front pully, but I have since squeezed it enough to give me loads of slack but it hasn't made a difference.