ive got a piaggio nrg air cooled,its fitted with a malossi 70cc iron kit,a leo vince tt exhaust,standard air box with red malossi air filter fitted,iam having problems setting up the carb [dellorto 17.5}i problem ive got is when running on full throttle for a while like going up a lomg hill it seems like its running out of fuel and loses power{like out of fuel}if i pull over a let it idle for a few seconds it runs ok again,its got a 75 main jet fitted and the needle is on the first notch,please help guys

andyindeal, January 2011

I think you should check the diaphragm in the fuel tap and the vacuum hose to the fuel tap. If the diaphragm is split or the hose leaking then fuel will not flow properly to the carb. I think this would be a credible cause of the symptoms you described.
Hope it helps
JD

Jake's Dad, March 2011

Hi adam, i fitted a small clear in line fuel filter today,so i can see the petrol,filled the ped up with fuel and rode it for about 4 miles before it stared missing and loosing power, i looked at the filter and it was empty i undid the filler cap and still no fuel in filer,then i cupped my hand over the neck of the tank and blew into it,and fuel started to fill the filter!!! do you think it might be a reed valve fault and would the reed valve cause the faults,i look forward to your thoughts and would like to thank you for all your help so far!
andy

andyindeal, January 2011

hi,there is no metal parts on the float itself its all plastic,and the main jet is 75,its really doing my head in coz its running so well apart from this fault
andy

andyindeal, January 2011

is still sounds fuel related to me ,the float height may be wrong and need adjusting ,do you know if it has a metal bit on the float that pushes against the float needle as if it does then it can be adjusted as it sounds like the carb is emptying faster then it can fill up,other than that it may need a bigger main jet as like you say when you shut the throttle off it picks up a little bit thats because when you close the throttle it shuts of the air initially and makes it run slightly richer for a second or two.and if moving the slide needle circlip didnt help then the main jet may just not be big enough.i would take a look at the float and fuel height and then maybe fit a bigger main jet to it.some aftermarket dellorto carbs have a small fuel filter inside the fuel pipe banjo union and that may be blocked up basically the fuel pipe on the carb on some of them pushes onto a black plastic bit this is bolted to the carb with one 10mm hex headed bolt undo it and have a look at the white filter inside it.you could aslo try running it with the fuel cap off to see if its any better as it may be causing a vaccum in the fuel tank if the fuel cap breather hole is blocked.

adam bike doctor(of milton keynes motorcycle centre), January 2011

i managed to get to work on the ped today{saterday] i moved to circlip down to bottom notch on needle as susguested [it was on top notch] made no differance,ie if on full throttle for more than 200/300 yds,it seems like its run out of petrol,starts missing.looses power and stops,give the 2/3 seconds it fires up and runs normal, i did notice that if i back off the throttle when it starts missing it seems a bit better but still stalls,ive changed the fuel tap to a non vacume one, do you think it needs a bigger carb[got a 17.5 on it]many thanks for all your advice so far
andy

andyindeal, January 2011

well if it bogs down and you alrrady have lightweight rollers it may be running weka ,have you tried to alter the small circlips position on the carb slide needle?try it on the groove nearest the pointed end of the need le and see if it improves. the screeching noise that sounds like a belt slipping on a car is............the drive belt slipping :D,i would suggest fitting a malossi kevlar drive belt to it i had the same problem with a dragster i have with a 172 mallossi kit on it that used to screech until i put this type of belt on it.let me know how it goes ok.

adam bike doctor(of milton keynes motorcycle centre), January 2011

thanks for quick reply,so do you think ive got the carb set up ok?coz it does feel lke fuel fault,ie like running out of fuel,i think ive got 4.9 rollers in at the mo,allso forgot to say that when i pull away from cold there is a loud screeching noise that stops after about 200yards,like a noise a fan belt slipping on a car makes
thanks andy

andyindeal, January 2011

im pretty sure i answered this question below,its the rollers that are too heavy for the race exhasut you have on it andits not creating enough back pressure to make the engine run right.5 gram rollers or take 3 rollers out and try that leave the 3 in there in a triangular formation.

adam bike doctor (of milton keynes motorcycle centre), January 2011