Two stroke, how much smoke is too much?

[sergei]

Right, I have recently aquired a little 50cc two stroke Suzuki scooter.
I managed to get it going after buying 2 stroke oil and cleaning the plug.
What bothers me that there is just too much smoke if you rev it. Is it normal?
Are the piston ring expenisve for those?
The oil has separate tank (unlike lawn mower). Maybe oil proportion is wrong?
My mate has a Honda 250cc Two stroke and it smokes less (not much though, if you rev it stationary it would create smoke screen in no time).

[CaM]

run decent two stroke oil in it. not shithouse lawnmower stuff. castrol tts is a goodin. bout $25 a litre compared to $8 but it's well worth the coin coz it actually burns off, and is better for lubrication. I noticed a fiar difference when doing this. can't belive how cheap people are, buying pox oil etc. oh well
unless it's drawing oil from the gearbox due to a stuffed crank seal (if it has one. may be single speed direct drive style etc) then it'll jsut be over oiling.
drain the oil, chage it for somethign decent, and take it for a decent distance run/jsut use it for a week or so and see what happens. may begin to clear a bit once it's burnt excess oil residues and shit form the pipe.
if it's still smoking like shitloads you should be able to turn the oil rate back a little

[panda_dan]

Sounds like piston ring is rooted

I have one of these and i'v done over 11,000kms on it now

When i got it the guy said the important thing with them is not to rape them in the first km each morning - let it warm up properly. and also run good oil and 98 petrol

So i have always done that and it only smokes a little when it starts up and once its warm, no smoke.

Maybe you need to drain your oil, put some nice good oil in it, take it for a cain and see if the oil residues burn off. Might start going better you never know.

You could also change the oil proportion, but then you run the chance of not running enough oil in the petrol and you'll have issues. Or if the crank seal is buggered, you'll get oil leaking in from the transmission

As far as i know, to buy piston rings you have to buy a piston too. But then all you'll have to do is take the little sucker out and change it over and you'll be good to go

[fivebob]

Sounds like piston ring is rooted

How would ring seal affect the amount of oil injected into the mix on a two stroke???

I don't know about this particular engine, but smoke may be from the gear box if the crank seals are stuffed. Other than that there is usually some adjustment in the pump, it's usually connected to the throttle cable so you get more oil when the throttle is opened.

[panda_dan]

Good point 5 bob, premixed - it's not a car engine is it

But then why would mine blow smoke first thing on startup? Would that be because oil's heavier than petrol and it's been sitting overnight ?

[sergei]

Right, I am using Castrol 2 Stroke Motorbike oil (TT?), the bike was sitting for over 2 years with no running so original gas and oil drained into engine, so it had both oil and petrol tank empty, I took out the sparkplug plug and drained it out.
I left it idle for about 15 min to get it up the temp and then I took it for a drive, it was smoking a lot less after first 5 min (probably burned out all the crap inside). It actually drives fine (it has power) although it leaves a trail of blue smoke behind, not sure if it is supposed to happen? How to adjust oil mixture on those engines?
The gearbox is a funny one - CVT with a belt drive so I doubt there is oil there (although bikes are new thing to me so I could be wrong).
BTW engine runs very quiet.

[rollaholic]

how old is it sergei?

[sergei]

1994, done 9000kms...

[CaM]

they'll blow a bit of smoke. jsut watch other scooters round town of the same age for an indicator.
also if it's been sitting, not sure if it's commonplace, but all oil-injected type 2 strokes I've ever owned seem to smoke like a mofo after they've been sitting for a few months...
if it's leaving huge clouds of smoke then I'd be concerned. I've run bikes without trouble that leave a visible trail. had one or two that oil the plug if not fanged, that fill whole streets etc.

[Crucible]

Can you disconnect the pre oiler and premix the petrol ? I had a mate that had an old RD350 that had a buggered oiler, premixed his gas @ around 30:1 ratio and it was fine. Maybe try that to determine weather the oiler is playing up? I ran my KX125 on around 35:1 on Castrol TTS, had a slight haze under throttle but that was about it.

mmmm I used to love the smell of Castrol TTS burning off in a 2stroke.

[rollaholic]

remember 2 strokes burn pretty much all the oil put into them - if you really think its too much smoke, like someone said above, possibly the mixture ratio is wrong. my friend had a KSR (50cc kawasaki minibike type thing) and i had a street magic, his used to smoke alot more than mine and it turned out to be this problem.

[ollieboy]

Sepias have cvt so no oil. My bet is it will clear up after the engines been allowed to heat up. Remember two stokes don't have valves and unburnt oil can leak down into the combustion chamber(engines mounted so piston faces forward) and sometimes down into expansion chamber so it takes a bit to heat up the exhaust and get rid of the crap in there. On mine you can't adjust oil mixture its got a line from oil and a line from petrol with a wee T piece- oil is fed through a wee hole by capillary action from the fuel line (should be the same as all sepias were exactly the same). Oil smoke is fine if you are not losing power. Its only a problem when you have no oil smoke at all, then the engine seizes. Rebuilds are cheap as on these as well, I rebuilt my friends in about 2004 or 05 and the kit cost $90 for ring and all the gaskets.

[sergei]

cool to know that.
What about washer insert in CVT to limit the speed, does it have one?
I have pulled apart some of the bits from it and noticed that the carb was missing 1 hose completely.



The A did not had a hose at all, is it a drain of some sort regulated by B?
Is C idle adjustment? (it looks like it is going right through and sticking out inside so the "throttle" stops on it).
What about D? Mixture adjustment?

[ATAl]

Just a few rough guesses from what the carb on my bike looks like:

a: this will be a fuel drain / breather pipe - no need for a hose but a good idea to get the petrol away from a hot engine...

b: possibly a float level adjuster - I've got no idea really.

c: yep, idle speed adjuster

d: I'm never sure which is which, but that's either the pilot jet (for closed or very small throttle opening mixtures) or the idle mix screw, whichever one it is, the sunken one to the right will be the other.

[CaM]

c is idle mixture

the one with thespring on it that's slightly coverd = idle speed.

d=jets = o idea. one's likely a pilot jet, other may be an air correcter vent for flaot bowl? duno. all my bike carbs are different.

b = screw for drain valve which drains out of a.
a = dont need a hose off t. jsut a drain.

[85AW20v]

So Ollieboy - is that why it's called a Sepia - cosa da oila justa seepia into da petrola

[ollieboy]

Sorry its taken a wee while for me to reply, I don't come online often anymore.

My sepias dont have washers on the cvt to limit the speed so I assume they all don't, there is a little spring though that supposedly slows the scooter down and you can replace with a softer one but I never did and mine can go 80 km/h on a good day. The thing that hold it back is the exhaust, if you pull it apart and clean the inside then put it back together and drill some more holes in the end it will get a bit more go out of it.

That carb scares me aye, its so complicated. we figured out though that the yellow and black wires operate a wee solenoid in there maybe for a cold start or something.