Ive got a colnago ct2 when I went out the other day the cups came loose I had to walk the bike home not good , I tightened them up went out today and they are loose again gutted im thinking off selling the bike can it be fixed.
Because it is an older Italian bike it has an Italian threaded BB which is right hand thread on both sides. This has the effect that the one side always comes loose. Your only way forward is to use some threadlock on that cup and tighten it more than 40NM - say 50NM.
Dangerous just to say "Oh, It's an Italian thread they always come loose" given that there have been many hundreds of thousands f Italian threaded bikes built since the inception of Italian threads early in the 20th century - in fact it wasn't until the Wright Brothers patented the LH threaded BB and LH pedal thread that American and then British bikes adopted a LH drive side cup thread.
If initial assembly is correctly carried out, Italian BB threads, whilst they are more prone to loosen on the drive side (due to thread precession), are generally no more problematic than are BSC.
I'd recommend getting the BB shell properly inspected by a retailer used toi dealing with material at this level to ensure that you have no thread damage (as a loose cup takes some time to make itself obvious and it may have burred the thread), having the BB shell thread chased to correct and minor damage and faced - then the BB shell should be properly degreased so that the thread locker can work correctly and have the cups correctly installed as suggested with Loctite 248 paste or similar. It is essential that the threadlocker covers the threads in this process, though - otherwise you may, over time, develop the reverse problem, of the cups seizing into the frame due to galvanic corrosion. The Loctite should prevent this.
Well, I have just removed an Italian bottom bracket and had to resort to using a hammer on the spanner to loosen the cups enough to remove them! (I think I will scrub the frame threads and lube the replacement BB's threads before installing it ...)