The reason I asked, Vinson581, is that there are different reasons for each sort of smoking and we can narrow it down a lot by knowing what kind of smoking we're talking about.

Smoke from the exhaust has nothing to do with the washer and nut stuff. That means that oil is getting into the combustion process somewhere, (though I was once fooled by a car that'd had such a bad oil burning problem with the previous motor that the new one smoked on heavy throttle openings for a while due to oil that had accumulated in the exhaust system!). The report that your motor had begun to run clean on a previous ride but now smokes badly is ominous. The ring ends not being perfectly staggered around the bore is not going to be a cause. They are free to wander around wherever they want in a four stroke. Heavy smoking after running clean suggests the bore is scored, either from some debris getting in there or the wrist pin clip not doing its job and letting the pin slide to the side, or one or more rings broken. All unhappy events. Compression will be down from the expected figure in this case. Other than that, wild hopes can be valve guide leakage (unlikely) or a crankcase breather hose incorrectly put on a high vaccuum front of the carb fitting, sucking oil out into the mix. (again unlikely). See if the inside of the breather box is clean, also. Make sure your gas isn't contaminated. (No little brother dumping a bunch of oil into the gas to freak you out)
Who honed the cylinder? What sort of finish was put on? Too rough is no good because seating involves wearing a lot of material from the cylinder and its hard on the new rings, the cylinder holds lots of oil which can burn and create glazing. Too smooth is no good because the rings won't seat properly, the cylinder surface holds too little oil, and a slight irregularity in the bore can cause rings, rather than seating in, micro-flex problems and eventual ring fatigue and breakage.

The piston to bore clearance is ideally .002 to .004 inch in an air cooled motor. A good dial caliper is fine to measure this with. Measure the piston below the bottom ring land and in several places on the circumfrence. Remember the piston is not made round but is made with a 'cam' so that when the motor is at operating temperature it will expand to a round shape. Call the measurement what it is at the largest place, most likely across the skirt near the bottom. Measure the bore both near the top and near the bottom. Don't let the ring ridge at the top mess up the measurement. (You DID take the ridge out, didn't you? A different and maybe thinner base gasket can cause the top ring to whack this ridge and break)

Thats about exhaust smoke.

This design of Suzuki motor can smoke externally as well, besides the normal smoke after a rebuild from handling the parts with oily hands. The reason for the copper washers and acorn nuts is that those stud passages serve other uses. The top brake side stud passage is where the top end gets it's pressurised oil. The oil doesn't go right to the top but takes a louis in the head and goes to the cam bearings first, then pisse$ out onto the rockers before slopping around loose in the head chamber and falling back down the cam chain passage back to the crankcase. This particular copper/acorn duo isn't so critical, just a nice touch to ensure no oil leaks straight into the head chamber without doing the cam bearing first.
For some reason the designers of this head have the shifter side lower stud travel outside the gallery for a length of about one inch. Because of this both ends of the stud need sealing. The top end is sealed by the copper gasket washer and acorn nut, to keep oil from drizzling down and out. The bottom is sealed by a neoprene o-ring that goes on the stud after the cylinder is installed. The o-ring shrinks and hardens due to the heat it gets right by the combustion chamber so it must be replaced every time the head is removed or oil will seep up the gallery and out to a fin that directs it to run right down onto the exhaust pipe, hence smoking. There was no need for this outside inch, the designer could well have made the casting so that the stud gallery was all internal. What was he thinking? the o-ring is non standard thickness and one from an o-ring kit won't fit, you have to get the Suzuki ring, which the dealers never think to stock.

When the manual states the importance of the copper washers because of 'oil consumption' they are correct, but when I read that I attribute it to language syntax. The writer means that the oil will be consumed, requiring replacement. Not that it's being burned up IN the motor, but reducing the level none the less.

Hope this helps.

 

To add from an LTF250F and LTF300F manual

piston cylinder clearance - .0016-.002 - limit .005

ring end gap (ring in bore) - first and second ring - .004-.010 limit .028


These numbers are for the 250, 300(or 280) was just a bit higher. Should be pretty close to yours.

 

thanks guys. i think i am gonna take my cyclinder to a new place and get it honed, this should definetly fix the problem.

 

oh btw i think i put the rings on in all the same order accidently, and i am getting blow by, what do you think?

 

Well...a part of my post above said " ...The ring ends not being perfectly staggered around the bore is not going to be a cause...."

I tried.

 

no i mean i lined them up can this be the problem?

 

but thank you for you help i appriciate it.

v581

 

Not even if they're all lined up. It's just good practice to stagger the ring ends but you don't get significant leakage by the ring ends being lined up. The piston is a good bit smaller than the bore at the ring groove part and if there was much gas leagage then it would drop compression no matter where the ring ends were. That is not your problem and if you had x ray eyes you'd see they arent lined up like that anymore anyway since you've run the motor a good bit. You'll see if you end up stripping it down again.

No problem.

 

so should i go and get it honed? i never honed it the guy before me said that it was good, so i guess i should, also do these motors have vibration to them mine seems to vibrate a good bit compared to my vinson, or mabey because it is just a smaller motor?

 

Thu December 04, 2003 5:00 PM
...i have good rings, a fresh hone, new piston and rings...

Sat December 06, 2003 8:14 PM (NEW!)
... i never honed it the guy before me said that it was good,...

I don't know what to say.

If indeed the cylinder wasn't honed then your new rings will likely not seat properly.
Do a compression test. If it is more than 10% below the manufacturers stated number and you don't have a tight valve then something's wrong wit the bore. Did you end gap the rings? (file the ends a bit till the gap is correct for your bore.) If you didn't then maybe one or more has hit a tight spot and you have a broken ring. Did you put the rings on the right side up? The oil ring usually doesn't matter but the top two are marked so they go on the way they should. If the scraper is upside down it will act to pump oil up to the combustion chamber instead of scraping it back down.

If you have a broken ring it likely means the cylinder is scored deeply enough to need a rebore.
Then the weisco piston will be no good to you.

If it was running clean and now it smokes and nobody has put oil in your gas then something has gone for s&^% in your motor. You'll have to go in there. You can get away with reusing the head gasket but you should get a new o-ring. Get the element of an electric range red hot and put the head gasket on it and get it thoroughly hot, move it around. This will anneal the metal (make it soft) so you can compress it again. Do it when mom isn't looking. She won't understand.