basically 2weeks ago i put ma new 70s bak on and guess what ive BLOWN the piston , basically i was riding and when the bike was cold it flew (not as in cold as in ive jus startin tha engine and rid off with out waming up lol ) but after a couple of miles it started gurglleing at full throtal and was not going ova 40 with real bad pull off , i checked the plug and it was a greyish colour but the electrode bit was brownish so i up jetted da carb went for another spin and jus as i pulled up to home it died out , i think tha piston has ha hole in it because when i turn it ova on da electric start the exhaust starts coffing , so what do u think guys , was it wrong jettin , i had a 20.5 mm carb with a 112 jet on ma stage 6 racing 70s kit.
why do people use such huge jets YOU DONT NEED A 118 IN THERE arc: what you need to do is put say an 80 jet in. lighten the rollers and then see if it stalls above 10mph.. if it still dies at full throttle over 10mph ITS NOT YOUR JET ITS YOUR ROLLERS first off tho your gonna have to repair the damage from running twice the fuel you should be LOL start by ripping the barrel/piston off and have a good look at it, it does sound like poor reeds or a hole in the piston tho as backfires and poping/coghing are usually symptoms of incorrect compression. mabey your jet has fallen out of the bottom of the carb tho as this would cause what you describe, also the choke being on but DEFFO put the 118 on a shelf and forget it, aslong as you ride a scooter you will never need it
lol ok thanks , i took the head and bore off and looked at the piston it was basically black and on the corner of the piston looks like a bit has chipped out. but the bores fine ill have to get a new piston, but what was baffleing me was the fact that when i did a plug check it was greyish colour so i thought it was running lean , the reads were fine aswell , and sorry i was running a 112 so still was to much neways , . cheers minor
