Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Athame57 on August 12, 2025, 12:58:00 PM
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I took a very smokey and rattley Elen into the workshop today. Best case scenerio needs a new valve guide (Brazilian english?) worse a holed piston or something. We shall see when the lid comes off. But I couldn't find a valve guide in the CMSL plan here..... can anyone help?
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Items 58/59 are the valves ... guides are a "tube" around the outside of those nd don't appear to be in illustration.
They are pushed into the head casting to be fitted, then the valves threaded through them ... to then have their springs etc installed at the top end to hold and control them.
Effectively the guide is concentric to the valve stem/shaft in location.
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Hello mate, sorry you looked at the wrong picture, they are show on the same page as the cylinder head. Part Nos:- Inlet guides - 12202333315.
Exhaust guides - 12203333335.
DSS can obtain them for you, check price!!!
The CMSNL site shows them as being in stock at what seems to be a lesser price, but I do not know anything about their postage and packing.
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Megazip in Japan also have them in stock, reasonable price, 20% discount until end of today, BUT! often have unbelievable shipping charges. Have fun. Mike.
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Its the rubber valve stem seal that stops the oil going down the valve stem into the cylinder. First sign of problems with them is a puff of smoke at start up or when snapping the throttle closed at high revs. Mostly a progressive issue over time as they wear and harden.
The smoke is that of burnt oil and not petrol as over fuelling by a flooded carb.
Crankcase breather tube not blocked of kinked
Broken piston ring is a possibility
I would do a compression or leak down test first before tearing into the engine.
Regards
Dave
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Be aware that you can not just fit a valve guide and reassemble, the inside of the valve guide needs honing/reaming and the valve seat recutting, also the 350/400 fours do not have stem seals on the exhaust guides
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As already mentioned, unusual to get a sudden change in oil burning via guide and the oil going down through that way. Generally accumulative with wear over considerable mileage.
Possible ring break and compromise a cylinder. Run it after warming up and with a glass of oil with the breather pipe submerged to see if its sucking a vacuum in there and very thirsty :)
Could be a damaged piston, check that with a endoscope through the plug holes. Check plugs for an oily one too.
These 400 are stoic little buggers, running well with seriously compromised cylinder and piston very competently until finally found out how bad they've got :)
Has the motor been apart recently ?
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What I'm hoping ( and praying!) for is that it's a repeat of something that happened years ago, a tappet had come astray, also causing strange noise, reduced power and smoke. I guess I could have nursed my way home and checked myself, but the workshop was closer and in this heat and my less than brilliant health just now I really aren't up to the job of spannering myself :( Oh well, I'll wait to see the verdict.
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What I'm hoping ( and praying!) for is that it's a repeat of something that happened years ago, a tappet had come astray, also causing strange noise, reduced power and smoke. I guess I could have nursed my way home and checked myself, but the workshop was closer and in this heat and my less than brilliant health just now I really aren't up to the job of spannering myself :( Oh well, I'll wait to see the verdict.
Dont' worry mare, you are not the only one. In my case, Anno Domini means that what I used to call my 'onda 'ospital is now only a minor injuries unit. I even have to have help getting the 400 onto the hydraulic ramp now.
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Dont' worry mare,
LOL! Am I female horse?
(https://tse2.mm.bing.net/th/id/OIP.18O58R8A1jbsNoyD7sdGfgHaEO?rs=1&pid=ImgDetMain&o=7&rm=3)
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Oooh, you look gorgeous petal ;D what with all that raven hair and such.
Could have been a Freudian slip, as in it may turn into a bit of a Mare if its serious in nature of the problem.
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;D ;D ;D ;D
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OH Bollocks!!! Do NOT drink & type messages.
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Not your fault its the dyslexic spell check!
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KO, thanks.
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Due to a change in directon I've started a new thread over this. : https://www.sohc.co.uk/index.php/topic,32164.msg312544/topicseen.html#new