Topic: Bike Smoking

[Garryk]

Was out today enjoy my CB750 and good weather,she was riding perfect and no complaints, but I noticed when I stopped after a long ride there was some smoking coming from the casing round the front sprocket and chain area,was wondering is this normal.
1975 CB750 K5
Garryk

[dave500]

i would step away and call the police,or the bomb squad?

[Bob Wessner]

Any chance it's oil dripping onto a hot exhaust?

[Garryk]

Hi Bob,many thanks for your reply,was just sitting here thinking that and hoping, will check for a stain on the exhausts, havnt noticed any oil staining on the ground.
Garryk

ps: Checked the exhaust and found a bit of staining on the exhaust,so will run her tomorrow and check if that is where the smokes coming from, is my bike model fitted with a automatic chain oiler ?.

[Bob Wessner]

I don't know about the oiler on your model. Usually that oil, if excessive, ends up on your rear rim. Leaking oil will find its way to to lowest point before dripping off and this may not be near the source. You can try cleaning the cases and under side really well and dry it. Then spray a light coating of foot spray around that area and under the engine. After riding you should be able to track the leak back to the source as the oil will "wash " the powder off where ever it travels.

[bollingball]

Hi Bob,many thanks for your reply,was just sitting here thinking that and hoping, will check for a stain on the exhausts, havnt noticed any oil staining on the ground.
Garryk

ps: Checked the exhaust and found a bit of staining on the exhaust,so will run her tomorrow and check if that is where the smokes coming from, is my bike model fitted with a automatic chain oiler ?.

If it is there would be some mention about it and how to adj or turn it off. My 78 750k does not have one and I'm not sure what year they quit using them
So here is a bump somone will know but the manual will tell you.

[bjbuchanan]

Take the cover off to expose the sprocket area, that should eat up 15 mins of head scratching time itself it isn't fun. You will see the bigger "bolt" of the oiler and that little flat head adjuster. I'm not sure if having everything all together you will be able to adjust it but it is that simple. You just crank the flat head part all the way in and it will like 90% close it off. That is as good as it gets with the stock oiler.

May have to drop the little sprocket off, not sure really. Either way it isn't too much work. Another possibility is that the bottom of your shift cover is leaking at the back.

[nccb]

have you ridden it in a while?  It might just be water burning out of the oil and coming out the breather area?

[jamman718]

Mine was smoking while riding up long hill with a passenger on 1977 cb750; went away when we hit the flats.  What would be the cause of that one?

[bjbuchanan]

Jamman

A little blow by from worn engine or valve seals or it could be that you don't ride it much. Letting the bike sit a lot will give some minor symptoms of a tired engine that magically go away after a few heat cycles. Either way provably not much of an issue if the bike runs good

[jamman718]

Probably blow by as I ride it all the time.  Thanks for the info!

[Garryk]

Thanks everyone for your help, will look into all the suggestions above and hope something turns up, will update when I get a chance to ride her.
Respects to you all.
Garryk

[stickman]

GarryK:  Check your chain.  If there is visible oil showing, good chance it is the chain oiler.
Park it overnite on the sidestand.  Usually the fluid will find its way down the sidestand and leave a wet footprint on the floor.  Just try to eliminate the possibility that its gas leaking down from the tank, petcock, fuel lines or carb bowls.  Gas on hot exhaust is not a good thing.  Stickman

[flybox1]

valve cover/crankcase breather hose fumes?

[Garryk]

Thanks,will check these all out when I get bike up and running again.
Respects
Garryk