Pitpro 140 need help please.

[schmo140]

i have a pit pro 140 cc lifan thats bout a month old. it was fine and running, then i changed the tyre and tightened afew nuts and bolts, and now its a pig to start/ backfires thru the carby/ rattle,slap insided the head. i took it back to the shop and he reckons it was the valves, so i had him reset the valves. that made no differrence. i completely rebuilt the carby thinking it mite have been bocked jets or something. but nothing still.
im thinking now it may be the timing and was wondering does anyone have any useful input, coz im sick of seeing it sit in my shed doing nothing. i dont want to take it back to the shop and i dont know how to retime it, or if it even is that...
PLEASE HELP ME!!!!
AND MERRY XMAS

 

[crazzy #1]

did you pinch any lines?

 

[schmo140]

..

naar bro. checked em all over. anything else u can think of????

 

[pitproxr]

did you tighten any engine bolts?top engine bolts?you may have tightend the top engine plate bolts which squishes the gasket,which will slightly bring the top plate and valves closer.any engine bolts you tightend untighten them a slight bit see if it helps

 

[edzy]

yeah did you tighten the 4 bolts on the end of the head?

 

[schmo140]

naar, i checked all that anyway. i cracekd em all and did em back up to the right torque setting. i dropped it back at the shop yesterday for them to have a look at. they still havnt got to it tho. he reckons itll be the valves or some ****, but i dunno. reckon he's trying to shaft me???

 

[Sidney]

yeah its your valves

 

[schmo140]

its now been like 5 days and i havnt heard from the shop. no bike on xmas, no bike over newyears. this is ******!!!

 

[schmo140]

They pulled it down and couldnt find anything, so they reckon its a electrical problem... theres another couple of days.....

 

[slick 50]

hey schmo
it could be a faulty cdi unit , have u tried that yet ,
i had a similar problem with mine the other day
i had an aftermarket hi rewv cdi unit in it and it was fine one day and buggered the next ,, i put the standard one back in and she runs sweet now

 

[schmo140]

i shall look into it
thanks man