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Looking for tank 1981 CB650, also got few questions

Posted: Wed Aug 02, 2017 1:36 pm
by Ryen
Hello everyone, I am the definition of a newbie when it comes to motorcycles. Bought a 81 CB650 a little over a week ago. No knowledge of bikes but wanted to get into something new. P.O. gave me the bike, says carbs were cleaned out and put together but had his hands full on other projects and couldn't get to it. Tank is rusted and has holes so I have to buy a new one.

1. Basically i've seen that 80-82 tanks fit? If so, do I have to adjust or modify anything with a different year bike?
2. My bike did not come with an automatic fuel valve? the manual I have tells me to remove tubes (next question) from it but I dont have it. is this a problem? Can i just do a direct fuel line into tank or will that not work/
3. What size tubes do I need to put for the small holes in between carbs 1&2 and 3&4. Also see a t fitting that connects fuel line to those two lines? I know i'm probably confusing the hell out of everyone but any help is appreciated. THANKS

Re: Looking for tank 1981 CB650, also got few questions

Posted: Thu Aug 03, 2017 5:03 am
by Folsoml
Ryen wrote:1. Basically i've seen that 80-82 tanks fit? If so, do I have to adjust or modify anything with a different year bike?
2. My bike did not come with an automatic fuel valve? the manual I have tells me to remove tubes (next question) from it but I dont have it. is this a problem? Can i just do a direct fuel line into tank or will that not work/
3. What size tubes do I need to put for the small holes in between carbs 1&2 and 3&4. Also see a t fitting that connects fuel line to those two lines? I know i'm probably confusing the hell out of everyone but any help is appreciated. THANKS



Welcome to the forum.

1. Any one of the non-nighthawk CB650 tanks will fit. What you need to be concerned about is the petcock. 79 and 80 use one size, while 81 and 82 each use a separate size. So if you get a tank that does not have a petcock, make sure you get one that fits..

2. No automatic fuel valve is not an issue. It usually take mine off first thing. The only thing you need to remember is to turn off the petcock when you shut the bike off. If you do not, you are counting on the float needles to stop the flow. If one of them fails, it can fill up the bowl until it overflows--either leaking gas everywhere or (worse) filling up your engine.

3. I don't know the exact size of tubing to use. These are vents rather than fuel lines. The T fitting connects to another tube that goes over the top of the airbox, but does not connect to anything.