Re: The dreaded Blue Smoke from modern 4 strokes!

Thread approved.
This might turn out to be a good discussion.
In our opinion, most of these cases are because of negligence. If one does not care of their motorcycle, it is going to give out be it a larger capacity one or smaller.
Your observation and your reason MIGHT be justified because if regular traffic and average speed are kept constant, smaller capacity motorcycles do have to rev higher. But then again, we firmly believe that the motorcycles can take that if proper care is taken.
We'd love to hear the thoughts of other people though...

Re: The dreaded Blue Smoke from modern 4 strokes!

Could you please shed some more light on the blue smoke issue?

Re: The dreaded Blue Smoke from modern 4 strokes!

Yeah, usually people buy bike and forget that it needs servicing. The most common cause of the blue smoke is not changing engine oil. Usually small capacity bike owners don't care about these things.

Re: The dreaded Blue Smoke from modern 4 strokes!

Previously I had a Honda Dream Yuga which I owned for 6 yrs/60000 kms. I used to ride it rough but would change engine oil every 4K KMs without miss, I was obsessed about writing down the service intervals in the owners manual to keep track of this. By the time I sold it was still running very well. The downside of me revving the nuts out of it was that once in the 60K Kms I had oil leaking from head gasket, which was a simple fix. What surprises me that many of the bikes I observe blue smoke are ridden by middle-aged folks who dont seem likely to revv that hard.

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Possible indication of engine oil getting burned along with fuel. In most cases you can also notice oil marks in the silencer where smoke comes out.

Re: The dreaded Blue Smoke from modern 4 strokes!

I think this blue smoke issue is caused because of the engine's head gasket going bad.It allows Oil to get into combustion chamber.Which,like a 2 stroke,gets combusted with the petrol and like how 2 stroke get their blue smoke.

It's funny how we love 2T Blue smoke but hate it coming from a 4T lol

Re: The dreaded Blue Smoke from modern 4 strokes!

Blue smoke means the engine is burning oil. The most common sources of oil being burned in 4-stroke motors are worn valve guides or worn piston rings, with rings being the more common. Worn rings are the result of dirty oil, which provides a source of abrasives to the cylinder wall, either through metal shavings from inside the motor, or just plain dirt getting past the breather. As the contaminants flow across the cylinder walls, the rings press them against the wall and create scores and grooves that oil can pass through. Also, the compression rings (the two or three rings closest to the top of the piston) actually have pressure relief gaps in them. If they get clogged with contaminants, the rings will be forced away from the cylinder wall by the compression pressure and oil will be forced up into the compression chamber (this is known as blow-by). Changing the oil can help if the blow-by isn't too bad, especially if high-detergent oil is used and the bike isn't very old. In dusty or high-pollution conditions, oil should be changed at least every 4000km or so, especially with smaller bikes that have less oil to start with. Frequent short trips and stop-and-go traffic make the problem worse, as that kind of driving produces more combustion byproducts that can accumulate in the oil as well (carbon, imperfectly-burned hydrocarbons etc).

Worn rings/cylinder wall, or worn valve guide, are going to require some kind of rebuild. So best to start by doing an oil change and using a good oil to try to flush out the accumulated contamination, followed by another oil change to get rid of all the now-freefloating crud. Make sure that you're replacing the oil filter, or if the bike uses a permanent filter screen, that the screen is thoroughly clean, after both the change to the detergent oil, and the change to get rid of the dirty detergent oil.