Do 2 strokers always smoke?

[ikeepmychevytoo]

Hi motorcycle people! This is my first post in this section so pardon me if my question is overly basic.

I'm planning to drive a Trabant occasionally. A DDR car with ~650ccm two stroke engine that makes 26ps @ 4200 rpm. Drivable around 2000-3000 rpms, 5000 being max. Compression ratio is 7.8:1 if matters. It requires two stroke oil in 50:1 ratio.

I have no experience with two-strokers. I can tackle being an oddity in the neigbourhood but I just don't want to disturb people. If I properly mix oil with proper 50:1 ratio do I still make visible blue smoke? Are those blue smoke throwers are misused engines or thats an unavoidable condition in 2 cycle world.

I need your expertise here. May be I can save one Trabant from going thrash. Any input appreciated.

BTW, this is what it looks like.

 

[tom slick]

A properly tuned 2 cycle engine with good oil doesn't smoke much if at all.

 

[55Test]

In my experience, 2 stroke engines seem to smoke a little when under heavy load, but it's no more smoke than a 4 stroke engine that's burning a little oil.

 

[abycat]

with my old dirtbike i run a pretty heavy 25-1 mix in it so it smokes when its cold and when you drive really hard. It seems to smoke more when you run it at low rpm's with alot of throttle. My 2-stroke lawn equipment does not smoke much at all and they are mixed at 40-50 to 1. I do have an old leaf blower that is ran on a strong 40-1 mix and it does smoke a little. I heard that if you use bio diesel at 25-1 instead of 50-1 with the gas you will get no smoke and it lubricates better than 2-stroke oil. I am going to try it with the old leaf blower one day. Sweet car by the way I would drive it for sure. 2-strokes are very easy to make power. imagine some expansion chamber pipes and a bigger carb and that thing would fly.

I also seem to find that if you dont rev the engine up and always bog it they will create alot of carbon which can mess with things.

 

[oilboy123]

There are oils that don't smoke as much like Amsoil. I have not used them for anything but small gas engines. Try some oils out that claim to be low smoking, and see how you like them. Not sure what choices you have where you live. Might have to mail order.

Look for a low smoke, low odor product. Synthetic 2 stroke oils is what I like to use.

Have fun with the car.

 

[ikeepmychevytoo]

I'm getting the picture. I can get TCW-3 oil or even so-called synthetic ones. Also one local market carries Evinrude-Johnson HD-30 oils. May be I should pre-mix some 5 to 10 liters for better mixing. No fuel pump here, its gravity fed.

Very basic transportation with Cadillac style tail fins. Lean beauty.

User manual states low rpms should be avoided at high speeds. Coasting down at speed with light foot on accelerator is not advised for proper lubrication. A very different motoring school for me.

 

[stephen9666]

I think people often add too much oil in the gas. It's easy to not be careful or just try to get close and err on the side of too much oil.

 

[ikeepmychevytoo]

motorcycle forum is very active... thank you all for the quick replies!

Lots of Castrols here, avaible at every corner. Three quality levels, mineral, semi-syth and synthetic. I expect "synthetics" to be group III. Also I saw some Liqui-Moly, they seem heavier in consistency.

No special oils readily available, like racing oils. Equivalents of Redline or some racing Motuls have to be special ordered.

 

[Chris142]

Is there any motorcycle shops around or small engine shops that would carry high quality oil?

 

[ikeepmychevytoo]

Chris,

I wasn't quite observant for two-stroke oils until recently. I just took a peek at the supermarket racks. In boating section there were Evinrude and LuquiMoly oils in one construction market. On auto section there are Castrols; mineral, Magnatec and Edge series for 2cycle. Occasionally I see Mobil's 2T oils. All seem to comply with TCW-3.

I'm sure there must be some motorcycle shops that I never been. One of my frends used to ride a cross style (pardon my terminology, enduro?) BMW bike. Complaining that original service was expensive, he was able to locate an independent small shop.

 

[Loobed]

The Trabby was made in Russia, or it was a Russian design. I saw those things running around East Germany in 1989, 6 months before the wall came down. They smoked a lot, but that may be the poor quality communist TC oil. As others have said, get some good quality motorcycle TC oil.

 

[eljefino]

IDK what one can do to tune a trabby but with expansion chambers and stuff you can time an engine to lose less fuel + oil with every rev, by sucking it back in, or not ejecting it in the first place.

Since the cars ran with what must have been dreadful fuel and oil, anything you can try should work rather well. I heard good reviews about them starting in -40 degree weather because there wasn't any thick oil in the sump.

 

[Mik]

Given the technology that went into that car, I think you will have to learn to tolerate some smoking. Some oils will be less smokey (I would suspect scooter forums would be a good place to find some names) and a high quality synth may allow you to run a leaner oil mix, thereby reducing the smoke a bit more.

As for your question, so-called conventional two-strokes all smoke, some more than others (although the problem is of course noticeably worse on start-up). Newer DI two-strokes (like the E-TEC engines used in Evinrude outboards and some Ski-Doo snowmobiles) are virtually smokeless and odourless (not to mention cheaper on gas than competing four-strokes). Times have changed and modern DI two-strokes are very refined and powerful engines....

 

[dwendt44]

How is the oil mixed in that car?

When snowmobiles went to oil injection, some of them were set 'rich' on oil for break in. They were, of should be, turned down a bit after a few hours of use. Many weren't. Owners didn't know/didn't bother, and those snow machines smoked some.
I think some 2 stroke cycles were the same-set rich for break-in, and not re-set after.

 

[Cujet]

There are plenty of things you can do to reduce 2 stroke exhaust smoke.

The most important item is jetting or mixture. A fuel/air mixture too rich in fuel is going to smoke. As you go leaner, the low end running cleans up and the engine smokes less.

The type of oil you choose is important too. As is the type of fuel you choose. Ethanol in the fuel promotes misfires in 2 stroke engines, increasing the smoke.

A cold engine smokes much more than a warm engine.

Some 2 strokes have a tendency to pool oil in the bottom of the crankcase. This causes a massive cloud shortly after cold startup. There was a time when some 2 stroke engines came with a small drain bolt on the bottom of the crankcase. I believe the Yamaha RZ series had this.

Cylinder head, combustion chamber design plays a large role too. The "squish" area, or area around the perimeter of the combustion chamber should be close to the piston, creating a MSV, or mean squish velocity, ideal for the particular engine/situation. Many engines are improperly designed, with WAY too much clearance.

 

[boraticus]

"Many engines are improperly designed, with WAY too much clearance."

I shaved .030" off the squish band ridge on the heads of my RD350 to improve gas flow. Not certain how effective that was due to a number of other modifications made to the engine to improve gas flow. However, from what I've read, removing the .30" is supposed to contribute significantly to expediting gas and heat through the cylinder as well as slightly increasing compression. Thus aiding cooling of heads and cylinders, shifting more heat into the exhaust (improving gas flow) and ultimately making more power.

From my experience, two cycles smoke much more when cold. Not too much can be done about that. Once warm, a properly tuned two cycle engine shouldn't produce much visible smoke either idling or at rpm and that's with a decent conventional two cycle oil.

I'd pull the carb on the Trabant for a good cleaning and while I'm in there, I'd pull the engine head to examine the condition of internals for carbon build up. Take a good look at the exhaust ports for accumulation there. Being a low revving engine and likely operated in lower rpm range much of the time, you may have considerable carbon accumulating in the exhaust system thus slowing movement of exhaust gas. You may have to burn excess carbon/oil residue from the exhaust system. I like to pour a couple oz. of diesel fuel into exhaust pipes, swish it around inside thoroughly, spark it up with a butane/propane torch and once ignited, put some compressed air into it until it burns off. Caution. This method may discolour chrome pipes if excessive heat is applied.

 

[ikeepmychevytoo]

Straightforward valuable info! Looks like I asked this in the right forum. I get many keywords for further search. Although I need to do some homework before discussing combustion chambers,
I think I get the logic. Rich conditions bring the possibilites. Sounds more straightforward than 4 strokers.

Highest gear is freewheeled, coupled one-way. This makes operation on high speed either high rpm or near idle, to protect engine run too lean on mixture if I'm not mistaken. This thing has a choke. No gas level gaugage, just a dipstick. No pump. Fuel is gravity fed to a carburettor. Very basic set up. Tank holds 30 liters (~8 gal). And to sum up the procedure, manual advises to pre-premix in a 5 liter jug for proper pre-mixing.

So in practice, the right ratio obtainable only with some ambition for computing. I heard that people used to loosely guessing and plainly pouring some oil then just rocking the car. At times with any oil. With some care actually they may be not that smoky.

As Mik suggest, I saw some better oils (e.g. Addinol Super 408) recommending 1:100 instead of factory recomended 1:50. This is a general advice though, not engine specific.

Many thanks. Everyone.

 

[kmrcstintn]

I have a 2009 Genuine Rattler 110 2-stroke scooter with oil injection; mine smokes while the engine is still cold, but it reduces greatly once regular operating temperatures are achieved; I've used Amsoil HP Injector, Yamahalube 2-S (injector), Pennzoil 'Marine' Synthetic Blend, and Super Tech Marine 2-stroke oil; the Amsoil smokes the least of them all

 

[ac_tc]

"The most important item is jetting or mixture. A fuel/air mixture too rich in fuel is going to smoke. As you go leaner, the low end running cleans up and the engine smokes less."

This is true but....
Its also a wery effective way of getting holes in the piston
or engine seizure. If you start playing with the jets atleast read the plugs so the doesent start to get lightbrown or white.