Carb bowls overflowing - need a quick fix.

[Duc]

Carb no 2 and 4 (Kehilins) on my project bike Honda CB550 '77 are gushing petrol from the spiggot on the base of the float bowl. (Gushing not dripping)

I need a quick fix to sort this if anyone can help please.

Engine is going in for full strip down and recon but mechanic wants to hear the bike running first ( and I dont want any fires!).

Engine runs fine but its just too dangerous at the moment.

[paturoa]

gushing - is it the float overflow or the drain thingies?

If it is the overflow then you'll prob have to take the float bowls off to sort out why.

If it is the drain thingies then they would unlikely be gushing if done up. Are the o-rings there? Are the bolts there?

Have they been OK prior to this? If yes then what work has been done on them?

Photos

[Duc]

gushing - is it the float overflow or the drain thingies?

If it is the overflow then you'll prob have to take the float bowls off to sort out why.

If it is the drain thingies then they would unlikely be gushing if done up. Are the o-rings there? Are the bolts there?

Have they been OK prior to this? If yes then what work has been done on them?

Photos

Ah Ha ... you have probably helped me already... (overflow or drains)

It is most likely the drains - they come out the very bottom of the bowl and did not have any hoses on them. Maybe I can find the grub screw that controls these.

The bike is totally new to me - only got it last weekend.

[Grub]

The issue is that the needle valve in the float bowl isn't closing and thus stopping the fuel flooding into the bowl. No amout of dicking with the overflow will address the basic issue
- The needle valve is attached to a float
- As the bowl fills with gas, the float rises
- The needle attached to the float is pushed hard up into its seat thus closing off fuel flow.

So something in that sequence has gone wrong, places to look
- rusty needle that doesn't seat properly
- hole in the float so that it can't ... float
- needle detached from float

See how ya go from there

[Duc]

The issue is that the needle valve in the float bowl isn't closing and thus stopping the fuel flooding into the bowl. No amout of dicking with the overflow will address the basic issue
- The needle valve is attached to a float
- As the bowl fills with gas, the float rises
- The needle attached to the float is pushed hard up into its seat thus closing off fuel flow.

So something in that sequence has gone wrong, places to look
- rusty needle that doesn't seat properly
- hole in the float so that it can't ... float
- needle detached from float

See how ya go from there

Thanx Grub

I took a close look and it gushing out the overflow spigott and nothing to do with the drains. They are tight and in place and have o rings. I will follow your procedure now I have a better understanding of the bits. I have a parts manual and a workshop manual to assist me as well.

Thanx for advice guys.

[Kickaha]

I need a quick fix to sort this if anyone can help please.

A bit of a tap with a spanner or scewdriver will quite often provide a temp fix, but ideally strip and clean them and inspect both needle and seat when you have them apart for wear

[Drew]

A bit of a tap with a spanner or scewdriver will quite often provide a temp fix, but ideally strip and clean them and inspect both needle and seat when you have them apart for wear

I concur, give them a wee rapping with the handle end of a ratchet, while the fuel tap is turned on, most of the time it sorts it out. If it does stop the leak, drain the carbs afterwards, with the tap off, tighten the drain screws up, and turn the gas back on. This will tell you if ya need to strip and clean them, or if it was just a lack of use thing.

[Duc]

BIt hard to tell from my manual / parts book but...Anyone know if I can pull the bowls from the bottom without removing the whole carb assembly. Maybe I can access the float and the needle that way...

....if wacking them with a large hammer does not work.

[Mr Merde]

Dont fill them with petrol.

Empty the tank.



Mr

[Grub]

Not sure about your bike, the last one I did was the FXR and the bowl can be taken off easily with everything else in place (except the battery!!!!!!- no sparks is a cool idea)

[Duc]

The "technical tap" with the end of the socket wrench has worked on the offending carbs. (Gave the other two a tap as well so they behaved ).

I will be able to safely ride it to the mechanic so he can check how she runs before we pull the engine and start a recon.

I figure its going to me much easier to recon the carbs on the bench than in situ.

Thanx to all for advice and help.

[JimBob]

why does the mechanic need the bike running before he does a recon?
And if it is running OK why does it need a recon?
Heard of being lead up the garden path?

[Duc]

why does the mechanic need the bike running before he does a recon?
And if it is running OK why does it need a recon?
Heard of being lead up the garden path?

Cos "OK" aint good enough for me and this is a thirty year old engine that I do not want to let me down when I am somewhere "up the garden path".

I thought it worth doing the mechanicals properly when engine is out of frame and easy to work on. Makes polishing up the engine easier too.