Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: royhall on September 22, 2015, 05:22:43 PM
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Could somebody answer a couple of questions about the CB350F.
1. What size are the petrol pipes to the carbs.
2. What does this spigot on the airbox connect to.
[attach=1]
[attach=2]
3. Does the earth strap on the loom connect to the battery box mounting bolt. That appears to be where it reaches, but wouldn't have thought that's a very good earth point due to the rubber mounting.
[attach=3]
Thank you in advance.
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The spigot goes to a drain tube to drain moisture away.
The rubber mounting should have a steel tube inside it, which would provide an earth. Not 100% certain where it goes exactly, but if it's the right length for it to connect at that point, go for it.
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That breather pipe joined with the breather from the valve cover on mine. My earth strap was mounted down near the end mount on the right hand side
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The crankcase breather is supposed to feed back to a plastic doofer that fits under the air filter to recirculate the blow by gases but mine just hangs down. I'd rather not clog my air filter up with oily gases.
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The Petrol pipe should be 5mm ID.
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Mike.
What's a plastic doofer.
My parts book doesn't show any additional vent bits on the 350F. Fairly sure the airbox spigot must connect to something though as it would pull in unfiltered air if it was an open drain hose?
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When I stripped mine the other day the breather and the drain both joint and then went down between then engine and swing arm. I'll see if I can find it a take a pic for you.
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Thanks Bullit. Did it have a small filter like device attached anywhere?
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Hi Roy,
This of any use - CB400F? One of the 'tubes' has a pinch end which normally seals but is pinched during maintenance to release any build up - it'd make sense it being the air manifold .... but I'm away from my bike & can't verify.
Cheers,
Simon
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Thanks Lobo. The 350 doesn't have the breather chamber under the air filter (it wasn't on the bike and it's not in the parts diagram). Looks like both breathers rocker and plenum chamber are just dumped to atmosphere beneath the bike. I guess they got a bit more Eco in 1975. Parts book just shows two plain pipes? Surely the plenum chamber pipe will be blocked during normal running or it will draw unfiltered air through the open pipe?
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The end of the chamber drain is modified and the length of it stops the air being sucked up, or so goes the theory
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Am I right then Bryan that on the 350 both pipes are just dumped to atmosphere without any reburn via the intake? And the plenum chamber and rocker box breathers are just lengths of open pipe? Cheers.
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Rocker box yes, plenum camber has somethind done at the open end like a squeezed split so that water can get out
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Got ya. So that part is probably going to be a part number item.
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And blimey me there it is. http://www.davidsilverspares.co.uk/CB400F-SUPER-SPORT-FOUR/part_188636/ Thanks Bryan.
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Plastic doofer =17271611010 breather chamber. Its supposedly a device, not fitted to 350fours, to decrease harmful emissions. They obviously don't work otherwise VW would be using them.
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That's it Roy. Could have sworn mine joined together at some point though.
Like the VW pun there Mike 👍
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Job done. Just fitted the new breather pipe on the bottom of the plenum chamber. Turns out it has a little air filter element fitted at the top so it doesn't matter if it sucks air in via the breather/drain. Clever stuff, that's another for the knackered old memory to retain.
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If it helps this is my breather tube, the outer sleeve is hard and brittle but this was how it was fitted to my bike, I haven't removed it yet as it will be destroyed when I split the crankcases tomorrow.
[attachimg=1]
HTH
NIGEL.
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Cheers for that and welcome to the forum. I assume from the name you also have a Suzuki. That's exactly how mine has gone back.