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Author Topic: CB350F - Carbs keeps overflowing  (Read 1538 times)

Offline jpmobius

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Re: CB350F - Carbs keeps overflowing
« Reply #40 on: Mar 13, 2019, 19:44:07 »
You should be able to simply replace the overflow tubes.  They are simply pressed into the bowl, but may also have some sort of sealant.  Aluminum expands slightly more than brass when heated, so after figuring out how you want to grab onto the bowl and tube, put them in the oven on max temp.  Any hobby store should have suitable brass tube.  If you can't get the exact size, you can sand a slightly too large diameter tube smaller by spinning it in a drill, or you could drill the bowl to fit the larger tube.  Having a larger hole in the end than the factory part will not impact how the bike runs.  Probably a good idea to seal the joint with a bit of epoxy before you install it.  Put the epoxy on the outside of the tube so as not to risk plugging the passageway. 
If your needle/seat assemblies leak, and don't have obvious visible damage, you can restore them by polishing the seat with some rubbing compound and a q-tip.
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0

Online WhyNot

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Re: CB350F - Carbs keeps overflowing
« Reply #41 on: Mar 14, 2019, 13:05:38 »
You should be able to simply replace the overflow tubes.  They are simply pressed into the bowl, but may also have some sort of sealant.  Aluminum expands slightly more than brass when heated, so after figuring out how you want to grab onto the bowl and tube, put them in the oven on max temp.  Any hobby store should have suitable brass tube.  If you can't get the exact size, you can sand a slightly too large diameter tube smaller by spinning it in a drill, or you could drill the bowl to fit the larger tube.  Having a larger hole in the end than the factory part will not impact how the bike runs.  Probably a good idea to seal the joint with a bit of epoxy before you install it.  Put the epoxy on the outside of the tube so as not to risk plugging the passageway. 
If your needle/seat assemblies leak, and don't have obvious visible damage, you can restore them by polishing the seat with some rubbing compound and a q-tip.

Thanks for the info, I have a few bowls of another kind that need tubes..........was gonna toss them......but......
1975 CB750K5
1974 CB350F

Offline tahitianrider

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Re: CB350F - Carbs keeps overflowing
« Reply #42 on: Mar 15, 2019, 06:31:41 »
Yeah you can probably find some, but they are very thin though, not sure if 1mm inner diameter tubes would fit.
https://www.amazon.com/Engineering-KS9830-Thin-Brass-Tube/dp/B005WPAW10

However the tube does seems to have a bigger diameter on the outside par of the bowls than on the inside parts.

I'll try to polish my seats if I still have leaking issues after re installing my fixed bowls.
'94 BMW K75 Racer
'84 Yamaha XJ 600 "Rocket" Racer
'76 CB 360 old school cafe
'96 CM 125 Brat bike
'80 CX 500 Racer
'73 CB350F Scrambler
'77 CB750F2
'70 CZ 125 vintage 2 stroke!
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Offline pidjones

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Re: CB350F - Carbs keeps overflowing
« Reply #43 on: Mar 15, 2019, 07:27:08 »
Aren't there any automotive radiator repair shops around you? They could solder that up quickly if you haven't put anything but solder and flux on so far.
"Love 'em all.... Let God sort 'em out!"

Offline tahitianrider

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Re: CB350F - Carbs keeps overflowing
« Reply #44 on: Mar 15, 2019, 08:17:42 »
Not really unfortunately, problem in France is that anything related to car or automotive, like repair shops, etc. are extremely expensive and usually do not do a very good job...
Especially in big cities like where I live. They'd charge about 45$ per bowl just to solder that... I'd be better off buying new bowls.
'94 BMW K75 Racer
'84 Yamaha XJ 600 "Rocket" Racer
'76 CB 360 old school cafe
'96 CM 125 Brat bike
'80 CX 500 Racer
'73 CB350F Scrambler
'77 CB750F2
'70 CZ 125 vintage 2 stroke!
www.tomracingdesigns.com

Offline irk miller

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Re: CB350F - Carbs keeps overflowing
« Reply #45 on: Mar 15, 2019, 08:35:04 »
Plus, it's just an overflow tube.  Anything that will seat into those holes, or the size of a drilled out hole, will be fine.  The size of the inner diameter is irrelevant.

Offline tahitianrider

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    • tomracingdesigns.com
'94 BMW K75 Racer
'84 Yamaha XJ 600 "Rocket" Racer
'76 CB 360 old school cafe
'96 CM 125 Brat bike
'80 CX 500 Racer
'73 CB350F Scrambler
'77 CB750F2
'70 CZ 125 vintage 2 stroke!
www.tomracingdesigns.com

Offline pidjones

  • Posts: 882
Re: CB350F - Carbs keeps overflowing
« Reply #47 on: Mar 17, 2019, 20:28:31 »
I think (no proof, though) that the top is rounded with a small hole to reduce fuel splashing into the tube while riding on rough roads.
"Love 'em all.... Let God sort 'em out!"

Offline tahitianrider

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    • tomracingdesigns.com
Re: CB350F - Carbs keeps overflowing
« Reply #48 on: Mar 21, 2019, 16:59:53 »
Yes that is correct, the  top is rounded and smaller than the tube's body.

Well I finally got my carbs to stop leaking... thing is float height wasn't correct on many bowls, which is weird, Honda recommend 21mm float height on the 350 four, but they will keep leaking until about 28mm float height, so well, nevermind I'll stick with the big 28mm float height.

I tried one fixed soldered + JB weld bowl and it seems it didn't leak, well it did leak but that was because of the bad float height. I'll use the Bowls I fixed on my second 350 four project.
'94 BMW K75 Racer
'84 Yamaha XJ 600 "Rocket" Racer
'76 CB 360 old school cafe
'96 CM 125 Brat bike
'80 CX 500 Racer
'73 CB350F Scrambler
'77 CB750F2
'70 CZ 125 vintage 2 stroke!
www.tomracingdesigns.com