2 fuel lines for 72 CB 750???

[sctrtrmp]

HI Everybody, Thanks in advance for any help... I have recently purchased a 1972 CB 750 (Barn fresh) semi chopper. I am in the process of bringing it out of the 70s chopper scene and back to a relatively stock bike. Here's what sounds like a dumb question, and I feel dumb asking it, but I am at a loss... The bike came with one of those \"coffin\" style chopper gas tanks. It's dented, rusty and crusty and heading to the junk pile. I have purchased a replacement (stock) tank for the bike... Here's where the \"dumb\" part comes in... The coffin chopper tank had only one fuel outlet directly to the carbs. The stock replacement tank has TWO fuel lines coming out the bottom of the petcock. I have a Haynes manual for the 750, but there are NO pictures, or anything telling me where to run this additional fuel line. At first, I figured the extra line was an overflow return line and ran into the stock air filter housing, but I can't find any place to fit the line. Additionally, when the bike is running, some fuel leaks out of the extra line.  I've checked the rubber in the petcock and it looks fresh (not deteriorated or crunchy). I'd sure be appreciative if someone could tell me where the additional fuel line goes. Thanks again for your help and understanding. =) Tom:S

[JonnyB]

Hi Tom, Welcome to the site, and don't worry about asking daft questions, we've all been there, or will be a some point.

I have a 76 and a 78 CB750, and both have a pet cock with only one connection, I'm sure the early models are the same.

Is it possible you've got a tank from the DOHC model? or is this a US feature,
mine are both UK bikes

[FatFreddy]

I have checked my copy of an official Honda dealer shop manual, and you have a very early CB750K fuel tank. These tanks have two outlets from the fuel valve/cock because the early carbs had two fuel inlets (the left hand pair have a fuel inlet set in the middle of the two carb bodies, and the same for the right hand pair).

If your carbs are set up like this then just run a fuel line from each tank outlet to each carb inlet. But if your carbs have only the one fuel inlet then you'll need to join the two fuel lines from the tank with a T joint and then run one fuel line off this joint to the carb.

I have the opposite on my CB750! I have an early set of carbs with two fuel inlets and a later fuel tank with only the one fuel outlet. So i have had to join the fuel line from the carbs with a T joint and run a fuel line from this up to the tank.

Hope that solves it for you.
Cheers

[sctrtrmp]

Thank you SO much for the information! I was thinking about \"TEE\"ing the two fuel lines into one and running them both to the carbs but wanted some expert advice before doing something weird or wonky. Thanks again for the replies! You guys made my weekend! =) Tom