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SOHC.co.uk Forums => CB350/400 => Topic started by: mattsz on August 28, 2020, 09:57:27 PM

Title: carb float bowl drains
Post by: mattsz on August 28, 2020, 09:57:27 PM
Hi guys -

I've mounted my carbs to the bike just to fill them with fuel to see if all the bowls are filling and to check for leaks - yes, and none... so far.

Noob question: is opening the drain screws supposed to drain the fuel through the overflow hoses, or should the fuel just run out at the drain screws?  I'm guessing the latter (which mine are doing) is correct.  Sure would be nice and easy if the fuel drained out the hoses, much easier to collect!
Title: Re: carb float bowl drains
Post by: philward on August 28, 2020, 10:04:51 PM
Its the latter so your carbs are draining as they should - couldn't drain out of overflow pipes as the brass overflow tube in the bowl is above the level of the fuel level in the bowls. Drain screws and overflow tubes are 2 different purposes.
Just thank your lucky stars the fuel isn't coming out of overflow tubes!
Title: Re: carb float bowl drains
Post by: mattsz on August 28, 2020, 10:09:01 PM
Thanks philward!  It's just too bad the drain screw openings don't somehow lead to the overflow hoses for ease of draining.  But then I guess if you find fuel coming out the hose(s), you don't know if it's an overflow problem or a drain problem...

I did find it challenging to connect the temporary fuel supply and get the fuel flowing with all of my fingers crossed!  ;D
Title: Re: carb float bowl drains
Post by: mattsz on August 28, 2020, 10:49:03 PM
Anybody have a particular routine and/or piece(es) of equipment they use to quickly and easily drain the carbs?  I just had a terrible time using different size funnels and pieces of plastic bent into troughs to try to direct the fuel flow from the drains to a container - instead of it draining all over the crank cases...
Title: Re: carb float bowl drains
Post by: robvangulik on August 28, 2020, 11:39:09 PM
I've got an indestructable glas teacup that fits nicely under the carbs, just large enough to hold the contents of 1 floatbowl :)
Title: Re: carb float bowl drains
Post by: mike the bike on August 28, 2020, 11:42:14 PM
I run the engine with fuel off until it stalls, then a wodge of blue roll mops up what's left.
Title: Re: carb float bowl drains
Post by: mattsz on August 29, 2020, 12:11:35 AM
Thanks guys!

Running it dry isn't bad - only I'm working on carbs without a running engine...

I'll dig around for something that fits in there...
Title: Re: carb float bowl drains
Post by: taysidedragon on August 29, 2020, 12:15:55 AM
I got a petrol proof clear plastic bottle and cut the bottom off to make a shallow container that slides under the float bowl. Bit fiddly but works for me.
Title: Re: carb float bowl drains
Post by: H2Eric on August 29, 2020, 10:33:03 AM
Use an aluminium foil tray from a pie. The bonus is that you get to eat the pie, before messing about with petrol that is.
Title: Re: carb float bowl drains
Post by: mattsz on August 29, 2020, 11:40:56 AM
Mmmm, pie...

For the past six months, our local recycling center hasn't been accepting most household containers, due to Covid19 concerns.  I've got room in my basement, so I've just been stockpiling until they open back up again.  As a result, I've got a pretty wide and varied collection of containers - yogurt tubs, laundry detergent bottles, milk jugs - I'll paw through them and see if I can't find something I can cut down to size that will do...
Title: Re: carb float bowl drains
Post by: JezzaPeach on August 29, 2020, 12:10:03 PM
Cut down Chinese takeaway container. Same benefit as buying a pie 😁
Title: Re: carb float bowl drains
Post by: SteveD CB500K0 on August 29, 2020, 12:18:42 PM
Except that by the time you’ve finished cutting it down, you’re hungry again…


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Title: Re: carb float bowl drains
Post by: JezzaPeach on August 29, 2020, 01:07:44 PM
😂 😂 😂
Title: Re: carb float bowl drains
Post by: ST1100 on August 29, 2020, 01:28:06 PM
They are avail in various sizes...

https://www.ebay.co.uk/itm/Small-Form-A-Funnel-flexible-funnel-rubber-funnel-/282462178342
Title: Re: carb float bowl drains
Post by: mattsz on August 29, 2020, 04:14:14 PM
I came home from a recent hospital stay with one of these plastic "kidney dishes" - don't worry, it's unused!  It's about 8 inches long; cut down in height to fit beneath the carbs, it could work well...

https://www.amazon.com/500cc-Kidney-Shaped-Emesis-Basin/dp/B00EDO0UJA (https://www.amazon.com/500cc-Kidney-Shaped-Emesis-Basin/dp/B00EDO0UJA)

(https://images-na.ssl-images-amazon.com/images/I/214YTYbOcbL.jpg)
Title: Re: carb float bowl drains
Post by: mattsz on September 04, 2020, 12:11:50 AM
Just to follow up for fun... taking my cue from the form-a-funnel concept, I took this empty milk container (goddamn sideways thumbnails! >:():

[attach=1]

... and cut some bits out of it to use for directing fuel into a container:

[attach=2]

The closer piece includes the handle as a small funnel - it fits right up under the drain screw, doesn't foul on the overflow hoses, and I can even easily hold it by the "handle" part.  It doesn't work well on carb #3 due to all the hoses, cables, wires and clutch cover, so I cut a plain ol' "trough" for draining that bowl...  they work a treat!
Title: Re: carb float bowl drains
Post by: taysidedragon on September 04, 2020, 12:33:32 AM
Yours are fancier than mine! 😁
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