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CB750 / CB750 F1 smoking like a b*****d.
« on: April 19, 2013, 04:38:56 PM »
Hello Lads,
Just joined your site and I have question to kick off with.
My overbored CB750 F1 with CR oil cooler has started to smoke like a B****d.
My concern is that the smoking is down to wet sumping due to fall back from the extended, external oil line from the return outlet to the oil cooler. I say concern, that would be the best scenario I think. Either that or it's seepage from the valve seals.....although I did replace them in the rebuild.....Gut instinct says its a bad seal or valve guide.
Relevent spec: 836cc overbore / Dyna S ign / CR carbs / Accer coils / rebuilt engine by me 8 mths ago (I take any blame) / CR oil cooler and extended oil lines / High flow headers and pipe / non standard oil box..etc....
Starts first kick then aprox 30 seconds later comes the heavy blue / oil smoke which clears when warm, then she runs smokeless and very strongly as a rebuilt engine should. Stop for half hour or so and same problem.
I note that there is aprox three quarter of oil in the sump, never known what amount should rest there?
I had a similar problem with a Ducati 900 Bevel, turned out to be a combination of valve seals and crap valve stem tolerance.
Oh yes, it started smoking just after a routine oil and filter change, I used Silkolene semi 10/40...relevant??
I will have to work out how to reduce the kb size of my build pics to show engine detail.
Thoughts welcome...Cheers.
Just joined your site and I have question to kick off with.
My overbored CB750 F1 with CR oil cooler has started to smoke like a B****d.
My concern is that the smoking is down to wet sumping due to fall back from the extended, external oil line from the return outlet to the oil cooler. I say concern, that would be the best scenario I think. Either that or it's seepage from the valve seals.....although I did replace them in the rebuild.....Gut instinct says its a bad seal or valve guide.
Relevent spec: 836cc overbore / Dyna S ign / CR carbs / Accer coils / rebuilt engine by me 8 mths ago (I take any blame) / CR oil cooler and extended oil lines / High flow headers and pipe / non standard oil box..etc....
Starts first kick then aprox 30 seconds later comes the heavy blue / oil smoke which clears when warm, then she runs smokeless and very strongly as a rebuilt engine should. Stop for half hour or so and same problem.
I note that there is aprox three quarter of oil in the sump, never known what amount should rest there?
I had a similar problem with a Ducati 900 Bevel, turned out to be a combination of valve seals and crap valve stem tolerance.
Oh yes, it started smoking just after a routine oil and filter change, I used Silkolene semi 10/40...relevant??
I will have to work out how to reduce the kb size of my build pics to show engine detail.
Thoughts welcome...Cheers.