1978 CB750 wont start after sitting a week

[distinked]

Okay, so I'm picking up this bike I just bought tonight. The fellow mentioned over the phone that it starts fine but if you leave it for a number of days, it wont start easily. Without any more info than that for now, what are some things I can check before driving it home? He says this is happening ever since he had the carbs rebuilt. I'm thinking they are flooding the cylinders slowly over time and that a temporary fix would be to completely shut the fuel off when not in use... make sense?

I'll post more detailed "symptoms" once I get the bike to the house and have direct experience with the problem. Thanks! :)

[gonebiking-2]

Is this a  SOHC or a DOHC motor. You dont say how many miles its done. Does it blow out blue smoke from the exhaust if you leave it standing for more than week when you eventually get it started, and it misfires , backfires runs erraticaly etc before settling down to a steady smooth run ? If so your valve stem oil seals are on their way out and need replacing. However if its fuel, then it would belch out clouds of black sooty smoke and foul up the plugs until it been taken for a decent run to clear the cylinders. Turn the fuel cock into to the off position about half a mile from home, so as to lower the level of fuel in the bowl, then leave it for a week. Turn the fuel tap on and start the motor straightaway. If she fires up and runs then you know where the problem is and carb kit is all that is required to solve the problem.

[gonebiking-2]

Just a follow up on my previous but of advice regarding your bike. Have you found the problem yet?? If so what was it?