Old K&B 7.5...20+yrs sitting...genl help re lines/tubing

[frankdoman]

I have an OLD, square carb, K&B 7.5 from ~25 yrs ago...Can somebody tell me what the line/tube connections are that I see on the carb and motor? Looks like the connector on the cone of the carb itself must be for the line from the fuel tank since it goes direct to the carb (correct?)...but the one on the left of the cyl head with no tube on it goes where? the one on the lower unit goes where, if anywhere ? Please see the picture...help needed, real newbie.

Thanks, F

 

[topfuel443]

Frank, the nipple on the carb is for the fuel line from the tank.

The nipple on the head (without the tubing) is simply the water outlet for cooling. Leave it like it is.

The nipple on the right side of the lower unit, below the pinkish tubing is for the fuel tank pressure.

~James

 

[frankdoman]

Frank, the nipple on the carb is for the fuel line from the tank.
The nipple on the head (without the tubing) is simply the water outlet for cooling. Leave it like it is.

The nipple on the right side of the lower unit, below the pinkish tubing is for the fuel tank pressure.

~James

James, for the fuel tank pressure, do I need to run a line from that nipple to the fuel tank or what ? The rest of what you told me makes sense & I get it...this still a bit of a mystery. I guess the pressure is created by exhaust stroke or something, but does it iternally cause the fuel line to suck in fuel or do I need to somehow run a line to the tank to create pressure ? thanks...F

 

[topfuel443]

Frank, your tank should have two lines, one going to the nipple on the lower unit, and one going to the carb. The pressure line will be mounted high in the fuel tank and the fuel feed line will be mounted at its lowest point in the tank, most of the time in the left rear bottom corner of the tank. The engine is just a pump, the exhaust pressure will feed pressure to the tank, and the intake vacuum along with the exhaust pressure will feed fuel to the carb. One continuous cycle so to speak.

Its very simple really, dont over think it.

You will usually fill the tank through the carb line as well, once full, it will run out of the pressure line and you are ready for a run.

~James

 

[frankdoman]

Frank, your tank should have two lines, one going to the nipple on the lower unit, and one going to the carb. The pressure line will be mounted high in the fuel tank and the fuel feed line will be mounted at its lowest point in the tank, most of the time in the left rear bottom corner of the tank. The engine is just a pump, the exhaust pressure will feed pressure to the tank, and the intake vacuum along with the exhaust pressure will feed fuel to the carb. One continuous cycle so to speak.
Its very simple really, dont over think it.

You will usually fill the tank through the carb line as well, once full, it will run out of the pressure line and you are ready for a run.

~James

Got it James...thanks. Should I use a S or M size silicone tube for all of these lines ?

Frank

 

[topfuel443]

I would use medium line.

~James

 

[frankdoman]

I would use medium line.
~James

Medium line it is James....maybe next week I will order the stuff I need to really see if it will fire....by then I will know if it comes apart, gets cleaned up OK, no missing broken parts that I can't replace, and willing to take a chance that it fires up. So far so good, but still need to get further before spending any real $ as a "fire it up" pkg of stuff I need. Thanks...Frank