First place i looked was valve guide size . Machined a go/no go plug gauge to factory sizes and the bores in the head are spot on sized the valves and they are the same . Checked the rings they are fine and the bores are spot on . I've lapped the valve seats and new gaskets are in the post . Its just with all the bikes i've rebuilt i've never had anything like this .
I have 2 Ariel square fours , 3 Scotts , a Silk , Douglas Dragonfly (now half rebuilt) , a Triumph T120
and a Velocette 250 Mov
But this is my first Honda
RIght side smoking??
Pete, of all those classics that you own, the Honda is the one I'd least expect to be smokey! I'd be inclined to follow G's idea of the problem lying with the O-rings within the corners of the head gasket; the only shortcoming in such a suggestion is that the gasket usually bursts outward, thus creating a visible leak. Now, I'm no mechanical expert, but I guess it's possible for the gasket to fail in any direction. Follow this topic http://www.honda305.com/forums/viewtopic.php?t=4520 for more detailed info and make up your own mind; you'd think any failure would progress in the weakest area.
Probably a dumb Q, but have you closely, I mean, microscopically, inspected the head / barrel faces for signs of hairline cracks or other imperfections that would allow oil to seep on one side? A compression test should reveal something along those lines. The valve guides would need to be noticeably worn to make the motor a smokey-Joe. Pete
Just 'remembered' a potential problem with these engines. That is the cast iron 'skull' losing adhesion in the aluminium head, allowing oil seepage (usually out via the spark plug threads. A distant possibility but if you search this forum you might just find something. Or did I dream it?......... I wouldl take Steve's route initially and look for hairline cracks or marks in the joint face. Regards G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
right side smokingGoing to have another look at the state of the gaskets and seals as i can't think its anything else . The new gaskets should be here in a couple of days so before they get here i'm going to lap the head and barrel together so they are dead flat. Good idea about getting the head crack tested . I'm lucky enough to have that at work so its going to x-ray , NDT and UV dye .
Just forgot its only done 15,500 from new if thats any help . Pete
Just one or two more trivial thoughts. Rings in the right way up? Ring gaps spaced nicely around the piston? Valve guides loose in head? Residual oil in exhaust? - I sometime squirt oil in my silencers to 'preserve' them. I realise these are a bit desperate but when you've checked everything it's going to be something daft..... G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
right side smokingGet the head back tomorrow from crack test so we will see if there anything there . If not it just going to be a bloody good clean and a vey careful rebuild when the gaskets come.Trust the post to go strike just when i need something !
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