Two fuel lines on 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

[alan b]

Hi, the Honda petcock on the Honda tank had 2 outlets and 2 fuel lines.  1 goes to carbs 1 & 2 and the other to carbs 3 & 4. It doesn't matter which. If the petcock on the chopper tank has only one line then it must split to 2 lines on top of the carbs, otherwise you could not feed all the carbs. Check where the fuel line goes towards the carbs and see whether it splits into two, each split should feed each 'pair' of carbs. Get a length of pipe, cut it in half  and run one length from one side of the Honda petcock to 1 'pair' of carbs and the other side of the petcock to the other 'pair'. The 2nd outlet on the petcock should not just 'leak', both sides should run at the same speed. You should have the same quantities of fuel running to each 'pair' of carbs. Whatever you do, DO NOT try and run a fuel line into the air filter housing! AlanB  

[Firehawk46064]

hey man... the older style carbs have two fuel lines  ... one line goes to 2 cylinders and the other line goes to the other 2 :)

hope that helps!

if you're stuck ...come on over to www.hondachopper.com  ...there's a bunch of guys on there that can help ya if you have a 69-78 honda cb750 SOHC bike.

peace!