major gas leakage from carburator

 I am bringing an old 1975 CB70 up to speed and learning about engines
as I go (total novice here). The engine's great but all parts, cables,
etc are pretty old so that's were I'm starting. Recently I replaced the
throttle cables - removed the gas tank, swapped out the cables, and put
it back together again. When I started it up I noticed the engine noise
was a bit different, but sounding good nontheless - then I realized the
puddle of gasoline on the ground. It looks like the gasoline is
overflowing from the carburator through drainage tubes. I have to close
the gas tank valve in order for this to stop. I don't understand what
is going on and feel like I am missing somethingg simple in the system.
Any advice would be greatly appreciated. IR

 igor rodriguez wrote:

First, check to see if the float height is correct.  You'll probably
need to replace the float needle, seat, gasket, etc. as well as possibly
the float.

To test the float, drop it in a cup of gasoline.  Leave it for a bit..
If it sinks, it's toast.

 
igor rodriguez wrote:

My immediate thought is that one or more of your carbs' float valves is
not closing completely.  Either the float valve seat is hardened and
not sealiong, or some debris is stuck between the valve and the valve
seat.

You can figure out which carb (or carbs) it is by checking the overflow
tubes from each carb.  Once you figure out which one it is, take off
the float bowl (usually held on by four screws, EASILY stripped) and
remove and inspect the float valve and the float valve seat.  Float
valves are CHEAP, the easiest thing to do for 31 year old float valves
is simply to replace them.

Good luck, let us know what happens, and for God's sake, buy us a round
of drinks.

Oh wait, never mind, this isn't RMH.

 tomorrow@erols.com wrote:


On these old bikes, a set of good #3 Phillips screwdrivers is beyond
mandatory.  These fasteners were chosen because of the speed of
assembling bikes, not taking them apart.  This is one of the few tools
that I shelled out top money for (about $60 for 3) from the Snap-On
truck at work.

Also, I would suggest a set of Craftsman screw reversers (NOT Easy Outs)
for $20.  They have been a lifesaver for me.

If I do have stripped screws, I replace them with allen head screws if
at all possible.. Of course, it's damn near impossible to find 6-40 or
8-40 allen heads...

 

Tim and Polarhound have given you good advice.  Get on the VJMC.ORG mailing
list, Polarhound posts there frequently.

But I must ask what is a CB70?  I know about the CL70s and SL70s and mini
trail 70 but the CB 70 is  new to me.  Regardless, it is a Honda 70, so
motor problems can be solved.

Bryan