Two-Stroke Smoking Excessively

[ClareQuilty]

I bought a Tena the other day, seemed to be in good shape, and it also didn't seem to smoke, but since then driving it around I've found that it smokes more that it doesn't, but it isn't consistent. The smoke is pretty copious (you know the classic mosquito-fogger two-stroke that you see once in a while) and appears the be white, the bike runs well and has plenty of power. The mechanic that I took it to for a general check-up did say there was a little oil in the exhaust, but this was before I noticed the smoke.

I should also mention that when it smokes it does smell fairly bad as well.

So, what can cause this smoking? Any ideas? Does it mean the engine was run without auto-lube two-stroke oil previously? Could it be solved by a simple 'engine rebuild'? (last time I had a Tena rebuilt it was only 1,000 baht and worked like a charm, though that bike was just weak, not smoking.. this bike is strong running, but smoking).

[barefoot1988]

i willassume you are running autolubed, probably need some adjustment for that, way too much 2t. you can try empty out your 2t tank, and premixing 15ml per litre of petrol and see if its still happens

oil dripping out from exhaust is common among 2 strokers, so no need to worry about that. every pillion will experience 2t stain on pants and bag etc etc smoke stinking depends on what 2t you are using. sometimes certain brand 2t just produce more smoke. anyway there are strawberry flavored 2t

i dont think you got your tena rebuilt for 1000baht . . . more like a top overhaul or maybe just a top servicing

Edited March 30, 2012 by barefoot1988

[VocalNeal]

CQ,

Check or replace the air filter.

Fill up the autolube tank and run it for at least one tank of premix gas unless you are 100% sure auto lube is working. Previous owner may have been using premix for a reason. After say 1 tank of premix check the auto lube and if it has gone down top it up and try to exstimate the amount (shot glass) then you can calculate the ratio. If OK use normal fuel and take it for a hi speed blast for a a few Kms to blow out any residual oil.

Then get you mech to clean out the exhaust. If he doesn't know how, unlikely, but the last resort way is to heat up the inlet side with an oxyacetylene or oxypropane torch and when red turn of the fuel and simply use oxygen. It will burn out all the gunk. You will of course have to have the exhaust painted after!

Edited March 30, 2012 by VocalNeal

[ClareQuilty]

i dont think you got your tena rebuilt for 1000baht . . . more like a top overhaul or maybe just a top servicing

It was a new cylinder.. not sure whether that is a 'rebuild' or not. Saw it come out of the box, brand new, 580 baht. In addition he did various other things that took about 3 hours - I've no idea what those things were, but they seemed to involve lots of cleaning and scraping.

Regarding the current Tena, the responses so far are interesting - I always thought that lots of smoke meant the motor was 'worn out', but maybe thats with four-strokes. Sounds like maybe this problem could be fairly minor, hopefully.

[madjbs]

Is the bike water or air cooled? White smoke usually is a result of a blown head gasket on a water cooled engine, if it was due to excessive 2 stroke oil in the fuel the smoke would be a blueish colour.

Edited March 30, 2012 by madjbs

[poanoi]

My small pecker stopped smoking when it was empty oil,

downside was an annoying noice emerged after and it's still there even tho i now have oil innit (and smoke again)

[ClareQuilty]

CQ,

Check or replace the air filter.

Yeah, my guy replaced the air filter and the engine or gear oil - whatever that oil is that isn't the two-stroke oil - gave everything a bit of a cleaning with gasoline, and checked all the brakes and lights and so forth.

Is the bike water or air cooled? White smoke usually is a result of a blown head gasket on a water cooled engine, if it was due to excessive 2 stroke oil in the fuel the smoke would be a blueish colour.

The bike's just a little air-cooled 105cc engine. And its possible I'm a bit off on the smoke color - so far I've only ever seen it smoke when its driving at moderate speed (40-60), so I can't really turn around and examine the smoke in detail. When you just rev the bike sitting it doesn't seem to smoke, seems like it needs a load on it.

Edited March 31, 2012 by ClareQuilty

[ClareQuilty]

Fill up the autolube tank and run it for at least one tank of premix gas unless you are 100% sure auto lube is working. Previous owner may have been using premix for a reason.

I don't think its been established that the previous owner was using pre-mix, in fact I highly doubt it.

[VocalNeal]

CQ,

I that case it needs to ridden like you stole it for about 5 kms.

[madjbs]

If the autolube wasn't working and there was no oil in the fuel the engine would just seize while riding it, not smoke excessively. White smoke is from water not oil, if the bike is water cooled you most likely need a new head gasket. If the smoke is not white but blueish then the autolube could be supplying too much oil or there is a build up of oil in the exhaust or you might need a new piston and rings.

Edited April 1, 2012 by madjbs

[ClareQuilty]

I that case it needs to ridden like you stole it for about 5 kms.

Thanks VN. I have been riding it a bit, and have tried to do so with some verve. So far it is smoking a lot less, though it does still tend to be a bit smelly (to those who claim all two strokes are smelly, some of the other one's I've had aren't very much so).

[NaMah]

^{Sounds like the new ring hasn't seated properly yet. If it continues I would remove the head and cylinder and have the cylinder re-honed and then replace the ring. You can do the whole job in about an hour.}

Edited April 4, 2012 by NaMah

[VocalNeal]

though it does still tend to be a bit smelly (to those who claim all two strokes are smelly, some of the other one's I've had aren't very much so).

CQ,

Define smelly. All 2 strokes burn oil is that what you mean. I wouldn't describe that as smelly. Down wind of a pig farm is smelly.

[krading]

Check it's not sucking gearbox oil through a damaged / worn seal.

Don't know much about your bike but I had an old suzi 2 stroke that did that.

[thaicbr]

two strokes can be smelly depending on WHAT 2t oil you use. some smell AND smoke more then others. its worth finding a brand you like and sticking with it.

[ClareQuilty]

ThaiCBR - I haven't yet had to put in any auto-lube, as it was full when I bought it. I put various brands at various times in my other two strokes, with no problem - smell or excessive smoke.

^{Sounds like the new ring hasn't seated properly yet. If it continues I would remove the head and cylinder and have the cylinder re-honed and then replace the ring. You can do the whole job in about an hour.}

What new ring?

though it does still tend to be a bit smelly (to those who claim all two strokes are smelly, some of the other one's I've had aren't very much so).

Define smelly. All 2 strokes burn oil is that what you mean. I wouldn't describe that as smelly. Down wind of a pig farm is smelly.

Well it smells much worse than my other two-strokes, which really have only the very normal and inoffensive smoke-smell. This one stinks - acrid at times.

Check it's not sucking gearbox oil through a damaged / worn seal.

Don't know much about your bike but I had an old suzi 2 stroke that did that.

Its an old Tena - a 105cc little clutchless click-through-the-gears kind of bike. I'll have to take it to the mechanic and try to get him to check that gearbox oil idea.

Edited April 4, 2012 by ClareQuilty

[NaMah]

What new ring?

I misread your original post, my apology.

You can just remove the head, slide the cylinder off the studs and have the cylinder honed which is just a polish job that most engine shops can perform. Then you can simply replace the piston ring and you should end up with a good seal. Very inexpensive and not a lot of down time. If I were there I would offer to come over and do it for you.

Na Mah

[VocalNeal]

CQ,

Did you but this latest bike from a farmer? Is it possible the smell you are getting is burnt palm oil. Farmers will do strange things...

Drain the oil tank and fill it with something you know then ride the long way to work.

[bbradsby]

A piston ring on a 2-Stroke doesn't stop oil passage as on a 4T, as there's no oil on either side of it! the only oil present is deposited in atomized form via the carb. A bad trannie seal would introduce oil in the engine, tho. That would require surgery.

Do these things first before any surgical exercise:

Download your bike's Shop Manual.

Check that your spark plug is the exactly correct number, gapped to spec.

Drain your autolube oil tank, then fill with a Low Smoke synthetic oil from a real bike shop - else get Mobil Extra 2T synthetic from a gas station. Run the old stuff out with a good 20 kM's thrashing.

Have your autolube pump adjusted at a proper shop, or download the shop manual and DIY - even better.

Monitor coolant level very carefully. It you're losing coolant, and have no external leaks, there's your problem.

And, last & most importantly, know that if you ride a 2-Smoke like your Khun Yai, it'll load up, smoke and be generally an unhappy beast for the duration of your ownership period. If you like to putt around at low RPMs, youre on the wrong bike and need a Four Stroke. Back in tha day, had a girl-neighbor-friend who was sold a Yammie RD-400 as her first ever bike, for commuting... well, I saw how she putted around on it, know that'd never change, so I had to ring its neck for a few hours every saturday morning on the open road to clear it out enough to be rideable for her on Monday morning. We had a nice arrangement `:] You need to cane 'er like a red-headed stepchild.

[ClareQuilty]

Guys, I don't know how one would 'drain the oil tank'. I can't work on bikes, just ask the mechanic to do things. Anyway I dropped the bike off at one of my two favorite mechanics for a day or two 'check' of this problem, without specifying anything to be done. We'll see how it turns out - usually this guy is so careful about not charging anything that he won't do anything he'd have to bill more than 200 baht for without specific approval, and half the time he hands it back after having the bike for 2 days 'just adjusting' and charges 20 baht.

Thanks for your kind attention and suggestions. I didn't buy the bike from a farmer, but who knows who was the owner before..just got it at the bike shop from their 'back room' of elderly trade-ins, 5,000 baht. Its certainly possible that that owner drove the bike very slowly, as a lot of older Thais do with their older bikes, and/or that the bike sat a lot, which is also common if the owner has a newer bike or even a car. I've known many middle class families who keep a bike for just going 2-3 blocks to the market but use the car for everything further, and those bikes are usually pretty poor-running. Lastly as I've specified before, the bike has no 'cooling system' - its just air cooled, no water in it at all.

[soihok]

I wish someone would have let me clear the throat of an RD400 every week.

RD400 as a first bike----for commuting?

Deathwish?

[ClareQuilty]

Got the bike back tonight, he said it was fixed and charged me just 40 baht. I'll drive it a few days to see if its better - couldn't see in the dark if it was still super-smokey. For sure it still put out some smoke, but it didn't look like as much. Wonder what if anything he might've done?

[VocalNeal]

I wish someone would have let me clear the throat of an RD400 every week.

RD400 as a first bike----for commuting?

Deathwish?

One of the few bikes I regret not buying was an NS400R. Still, I wouldn't have it today but....I'll have to make do with what I have

Edited April 9, 2012 by VocalNeal

[soihok]

The NS400 was a rare beast, never hear of them now.

When my mates were burning around on Elsie's and Powervalves in the early - mid 80's, I had to make do with an X7 (which I eventually club raced) as I never had the money for much else. I blame the miners strike for that.

All changed in 1988 when I bought a brand new GSXR750 J, it was my dream bike, then someone stole it (and the following bike after that, a GSXR1100H). Then I got bored with things being stolen and left the country (one way flight to Dehli).

Good to know your smokey bike ain't smokey any more CQ.

[motorcrazy]

My Yamaha tzm smoked like crazy to,carb setting new piston ,and the job was done.

Everyting what smoke by 2 stroke its ok ,dont worry

[bbradsby]

I wish someone would have let me clear the throat of an RD400 every week.

RD400 as a first bike----for commuting?

Deathwish?

naw, she was an innocent doe-eyed lass. Sweet, but a bit broad of beam for my likes. Never been on a bike, the salesman saw her coming.