i got a ? its blowing white smoke

[fids05]

like when i rev it like 7 or 8 grand and up when im getting on it, it shoots out a white cloud of smoke out? spark plugs havnt been done in awhile.... jus thinking what it could be?

[Wade-Kat600]

spark plugs are best guess - not water cooled so it aint a head gasket - likely its not burning all the fuel

[StevieB]

Conventional wisdom:
White smoke- steam, coming from water cooling system (obviously not happening here)
Black smoke- carbon, rich mixture
Blue-grey smoke- oil leaking into combustion chamber, getting burned with air-oil mixture.

My thoughts: Either you mistook blue-grey for white, or somehow condensate water is finally getting turned to steam. How long after start-up does it happen? Get a bud to watch for the smoke, while he is following you- ask him what color it is.

[The CyberPoet]

It does raise an interesting question: are you running a jetkit? Did you get it dyno/tuned after install?
Your system might be going particularly lean (or rich, but I suspect lean and way-hot) at those RPMs.

White smoke can be oil if the oil is particularly highly heated.
At lower engine temps, it's usually water condensation being boiled out of the exhausts...

If concerned (i.e. - it's still doing it after 20 minutes of riding), I'd do a compression test and get some exhaust gas readings on a dyno to find out whether it's oil getting past where it should, or just fueling being off.

Cheers,
=-= The CyberPoet

[Mojoe]

I am thinking the smoke is more of a blue/gray that you are mistaking for white.
and if it is only happening when you come onto it, it is your rings. you need a ring job.
my 750 and 1100 are both doing the same thing.
if it is an older bike, then the rings are probably just wore out. if it is a newer bike with low mileage, get it checked right away. you might have one busted ring, which can screw up a cylinder pretty bad.

try starting the bike and repeatedly rev and slack off on the gas, quite quickly. bring it up to 7-8k each time. If you start getting gray/blue smoke...it's rings. if you get heavy black smoke, you are running rich. if you get a few small puffs of black smoke, that is normal cuz of the way you give/shut the throttle for this test.

to confirm it is the rings, do a compression when the bike is cold and has been sitting for a while. mark down the results for each cylinder. then do a wet test. put about a tbl spoon of oil in each cylinder and test again. if the difference is too great....like 8-10 lbs and more, you definately have some worn rings.

[fids05]

how hard are rings to do on this?? and what if i dont do them, will it hurt the engine pretty bad?

[fids05]

its 93 750cc

[Mojoe]

how hard are rings to do on this?? and what if i dont do them, will it hurt the engine pretty bad?

it depends on your budget, mechanical ability, time and space.

to be completely honest with you, unless you plan on keeping this bike 3 more years at least, don't even bother. my 92 was shooting a gray cloud of smoke each time I came onto it at about 60k miles. at 85k or so it was doing it when I let off the throttle and was running on compession. I also felt a significant power loss, but it would still go pretty good, being an 1100.
At about 90k miles and upward to the 120k or so miles I have on it, no one could bare to ride behind me. They would be eating my foul exhaust.

So...will it hurt your engine? No, if all it is is worn rings. The rings will just keep on wearing and it will smoke more as time goes by, as well as lose power. Of course your plugs will foul more, but nothing drastic will happen to the motor. In fact, when the crank came out of my engine, the mechanic said it was unbelieveable how great it was considering the mileage.

So if you are absolutely sure the smoke is not from your carbs, and it is light in color, it pretty much has to be your rings. if they are just wore...which is probably the case with a 93, then you are pretty much safe to run the bike. Ring jobs are not a major issue except that you have to bare with the smoke and slow loss of power. And as I said.....if you think you will get another bike in the next couple of years, don't even bother fixing it. If you can't do it yourself, it will cost you as much as the bike is worth.

if you do want to fix it, but don't have the time, space or mechanical ability to do an upper engine rebuild, you could always consider picking up another engine to replace it. It would definately be cheaper than having a dealer rip into it.

[The CyberPoet]

They would be eating my foul exhaust.

His bike smoked pretty badly, too...

So...will it hurt your engine? No, if all it is is worn rings.

It will eat through oil at an accelerated rate, and you'll have to stay atop of it. Depending on where you live (how strict the pollution requirements are & whether you have inspections), it may never pass inspection without repair. A thicker oil will make the bike harder to start, but will seal the rings better.

All that assumes it is worn rings. It could also be a damaged valve, bad valve spring, or too much fuel -- the best thing at this point is for you to pin down what it actually is, so you can make an educated decision on how to address it (l.e. whether to live with it or to fix it or to replace it, etc).

Cheers,
=-= The CyberPoet

[Mojoe]

They would be eating my foul exhaust.

His bike smoked pretty badly, too...

So...will it hurt your engine? No, if all it is is worn rings.

It will eat through oil at an accelerated rate, and you'll have to stay atop of it. Depending on where you live (how strict the pollution requirements are & whether you have inspections), it may never pass inspection without repair. A thicker oil will make the bike harder to start, but will seal the rings better.

All that assumes it is worn rings. It could also be a damaged valve, bad valve spring, or too much fuel -- the best thing at this point is for you to pin down what it actually is, so you can make an educated decision on how to address it (l.e. whether to live with it or to fix it or to replace it, etc).

Cheers,
=-= The CyberPoet

oh hell ya....it will eat oil like it is going out of style after a while. I could burn a quart in a day if I was playing hard or did alot of miles. I burn a quart every 7-800 miles with my current bike. So for sure keep an eye on the oil level.

and as CP said, it could be a valve problem...but it would have to be a valve guide.....not the valve seat itself..or the spring. neither of those have a way of allowing oil into a cylinder....but it can go in around the valve stem. if the smoke comes off as looking white to him, and it is not a liquid cooled engine, he pretty much has to be seeing gray/blue smoke. and that is small amounts of oil. the worse the oil leak into the cyclinder, the denser and darker the smoke becomes.

too much fuel would be more of a black cloud, wouldn't it?
and if it is running too lean, it doesn't smoke at all, does it?
It could be coming in around the valves.

the fisrt thing you need to be doing is a full compression test. compression dry, then wet.....and a leak down.

all my bikes smoke......from several problems.......so I am used to it.
it keeps the bugs away.

[The CyberPoet]

too much fuel would be more of a black cloud, wouldn't it?
and if it is running too lean, it doesn't smoke at all, does it?
It could be coming in around the valves.

I was thinking more along the lines of so lean as to crack a valve face (one of our members here had that issue previously & posted pics)... or a bent valve stem, depending on how long it's been since the valve clearance service (or ever, and whether it was done right).

KNOW THIS:
To get an accurate compression test, the valves need to be adjusted before hand (unless you know they were adjusted recently), so it's a good time to eyeball them for damages at the stem & springs.

Cheers,
=-= The CyberPoet

[Wade-Kat600]

if it is rings you can run a higher viscosity oil to slow down burn off and increase compression. Dont go too heavy as it will decrease flow through the lines.

[StevieB]

As it happens, my GF's Mazda MX6 has a oil consumption problem- much worse than what you describe. I am going to try 40W and then 50W oil if the 40 does not do the trick. I will post here how sucessful it is. Will try it this weekend.

[Wade-Kat600]

I hope you're not talkin sae 50 - Thats way too thick for effective flow.

a 20w50 isnt really going to help - i'd go with sae 40 and see if that doesnt help. I would hesitate to go any thicker.

[StevieB]

Not too much to loose, here- car has 280,000 miles on it, engine smokes pretty bad, and I have another car lined up for the motor. If I toast the motor, who cares? And anyway, trying the 40W first.

thanks for your concern, tho.