Topic: CB350F Carbs - assembly tips?

[gtmdriver]

I had a problem with nylon floats on a Moto Guzzi swelling and sticking due to the ethanol content of the petrol.

[flybox1]

The black foam ones wont lose buoyancy, but yes, when dry, they have a tendency to stick down if there is any roughness to the float pin, or, if in the down position, the float valve falls itself too low blocking the upward travel of the float. 
At some point, floats were designed to prevent falling to low.
tapping the carbs to free them up is fine.

[harisuluv]

At some point, floats were designed to prevent falling to low.

All SOHC carbs except for the 350f/400f have a second tang to adjust float "drop."

[dbbrian350F]

I am re-using all the brass - cleaned up, plus a slow jet from Harusluv (thanks James)

The float pin is quite short, but I have seen longer ones.  Couldn't say 100% mine are original, but the length difference cold be the variation between 21mm and 24mm.  I'll use the clear tube method Flybox has shown in other threads.

The float pin has a little sprung mini pin that might be sticky, causing your stuck floats from rising up.  I soaked mine in acetone to ensure they work.





Still curious if I should change the needle clip position - current length is 28mm. 




Any suggestions?

Brian

[harisuluv]

Looks quite clean, good job!  Don't mix up the float valves and seats.  They all have individual wear so mixing them up might mean a leak right off the bat.

[dbbrian350F]

Thanks James - means a lot coming from you.   

My favorite photo so far.



I have kept each carb parts in separate marked containers so not to mix up.

I am thinking I might use a little metal polish on the float pin points.  I put one set together and couldn't blow air thru so I think they are still pretty good.

[flybox1]

Nice work.  Those float pins do look original.
If the float valves internal spring was stuck, the float would push the valve up sooner, shutting off fuel.
Function of the float/valve can be inhibited by debris on the floats pivot pin preventing smooth swing, a wear dimple on the float tang surface the float valve tip catches on, wear on the float valve tip preventing good seal, or a pinched bowl gasket stopping the float.  ROUND 350F float bowl gaskets are notorious for this!  Get the formed ones.