Aerox Problems Please Help

Hi Folks Please help as I`m pulling my hair out (and I ain`t got much to start with) My daughters Aerox drives ok until you stop on a hill then it will hardly pull off. I have canged the variator (kept the standard weights) ,clutch,inlet manifold reeds fuel tap and cleaned the carb, it still would not go so I then changed the coil and cdi/ecu and it`s still the same, can someone give some idea`s of what is wrong before I do something stupid like put a match to it. Thanks

 

have you changed the belt?could be worn belt.when your pulling away on a hill is it revving high?sounds like to heavy rollers or the wrong clutch springs,more detail would be better tbh.

 

your clutch bell might of over heated and worn out , i had same sort of problem on my aprilia. so i changed the clutch and bell sorted the problem

 

Yes I changed the belt and it was still the same, yesterday I change the rollers I tried a few different sizes from 3.5g to 6.0g and it was still the same, I was told yesterday to check the oil in the diff because the old oil may have broken down and the diff may be overheating

 

Yes I have changed the clutch bell ,the old one was looking a bit blue where it had got hot

 

When you say it will hardly pull off do you mean that the engine is revving but the bikes not moving quick or do you mean that the engine bogs or doesn't rev under load.
If the engine revs okay then it's probably a drivei ssue,Take the casing off and run the engine apply the back brake to simulate a load and slowly open the throttle to see what happens. If your belt or clutch are slipping then this will show.
Is the face of the variator smooth or ridged cos any ridges will prevent the belt moving smoothly. and is the variator outer pulley fitted correctly with the splines intact . The pulley splines need to fit proud of the shaft splines so the retaining nut can be fully tight against the pulley not the shaft (have a look at the pedparts blog on this issue.)

Is the bike standard or deristricted.

 

The bike doesn`t rev under load every thing is standard except for the exhaust. we have had this bike for 3 yrs and its been running fine its only the last month its been playing up and I`ve changed nearly every thing I can think of

 

If the engine is bogging or not revving under load then I would direct my attention to the cylinder, I would do a compression test as a start, the rings could be worn losing compression and power. What mileage has it done?

 

I was thinking along those lines myself but was putting it off, it`s done 11,000 mls

 

Right I`ve done a compression test and its reading 150psi can you tell me what size jet I should be using for a vance and hines tt exhaust and what size rollers. I think the jet in it now is an 84 or 86

 

What carb is it fitted with. post 2003 Aerox's were fitted with a 12mm Gurtner and the main jet was 62, when a sports exhaust is fitted jet 10% to a 68 or a 70 if a 70cc kit is fitted.
Earlier aerox's were fitted with 17.5mm dellorto's and I think that the main jet was in the mid 70's range. so an 84 or 86 in a 50cc is probably too large for either carbs.
150psi is fine rollers around 4-4.5g

 

If you've got the 12mm dellorto phbn manual choke carb the 86 is the standard jet size

 

The jet is an 86 and was running okay before. New info, my neighbour downloaded a workshop manual in the trouble shoot section it mentions about struggling up hill and they suggest the clutch spring has lost its tension,so I`ve ordered some to see if it makes a difference

 

In the clutch assembly there are what looks like brake shoes which are held closed by springs but open under centrifugal force. There is also the contra spring which forces the faces of the drive to grip the belt. Thinking about it, it could be that the contra spring is not applying enough pressure to grip the belt and it is slipping under load.
Worn clutch springs would let the clutch engage too early.
Keep us posted.

 

Right I`ve changed the contra spring, have tried 3 different sizes and its still the same,also changed the belt and variator weights (4.5g)

 

If the bike pulls of properly on the flat and achieves maximum speed and goes uphill in a reasonable way (I've seen Swansea hills) then it's safe to asume that the engine is running fine and the issue is with the drive train.
The variator is the first part I would check again, it's function is to act like a variable speed transmission and regulate the engine speed. A 50cc moped has a very narrow powerband and a well set up variator will allow the engine to stay within this range to allow maximum power delivery at all times. The weight of the rollers control the speed at which it operates, heavier weights open sooner so the belt is fully out at lower revs. This usually means that the engine is not yet in it's powerband and will struggle to get there as it has to increase revs to increase road speed. Lighter rollers take longer to get out and allow the engine to rev higher into the powerband and keep it there while the variator does all the acceleration whilst the motor is giving full power. Too light a roller and the engine revs it's nuts off and goes nowhere cos the rollers are too light to overcome the resistance of the variator and the belt won't fully open.

In your case if the bike runs well under normal use but only suffers during hillstarts then it suggests that the variator is opening too soon so the engine is trying to pull off whilst it is not in it's powerband . The standard Aerox variator is okay with a restricted bike but as soon as you derestrict it and fit a sports pipe it's limitations show as it struggles to hold the engine at the higher revs where the power is. A restricted aerox runs at just over 7000 revs max whilst a derestricted bike hits it's maximum power at over 9000 revs which is really out of the standard variators range. All test done by Pedparts using their rolling road show that one of the first parts to bin even at a mild state of tuning is the variator.
Issues with the clutch springs are springs too soft clutch engages drive too early, springs too hard clutch engages too late at high revs.
the contra spring controls the grip on the belt, too loose and it will slip to hard and it will grip the belt slowing variator activation and sap power. Sorry if it seems like I'm trying to teach you to suck eggs but I know what it's
like when everything seems right but it won't work properly. I couldn't get my bike to run after fitting the 70 kit it would fire up then just die, if I replaced the long reach plug with a short reach one it would run so I was convinced that either I had a duff plug or the coil was packing up. It was in fact neither I just needed to remove the snorkel from the airbox to increase the airflow (confusing cos it had run okay with it),
Let us know how you get on.

 

Thanks for taking the time to help me out. Bit of a new twist, just before these problems started I changed the wading in the exhaust as I thought the exhaust had become noisy. Today out of desperation I pulled the wadding out but the bike was worse up hill, a friend of mine has told me that a 2 stroke needs some back pressure from the exhaust for it to run properly,have you ever heard of this and if so how much wadding should I put in as I don`t want to block it up

 

Your friend is correct and performance is certainly affected by exhaust back pressure. Changing the exhaust padding may well be the root of the problem you have been experiencing. Unfortunatley each exhaust is different and the amount of padding required varies. Have a word with someone like Pedparts I'm sure they will be able to advise you.

 

the packing in the exhaust will not effect it ...as the back preassure is from the manifold and the expansion chamber all the packing does is stops the noise that the back preassure makes aka the tinny sound ....but in a way he is right as it does hold the preassure better but you will not notice it on a standard 50cc

 

It seems to be sorted put new wadding in the exhaust and the thing is flying 45 -50 on the flat and 35-40 uphill still a bit peeved as I changed all these parts and I only needed to sort the wadding out ,never mind we live and learn . I`d like to thank everyone concerned for their help, it`s been very helpful