Talk:Two-stroke engine

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new messsage[edit]

mhbowen: would like to add my experience to this.

VRO - Variable Ratio Oiler - introduced to outboard engines helping to vary the oil ratio from 50:1 for high rpm's (~5200 rpm) down to 150:1 during idle at 700 rpm. This reduced the amout of black carbon buildup from excessive oil-to-fuel mixture within the exaust section of the outboard engine. Problems occured within earlier 2-stroke oils inside the oil reserve container. The earlier mixtures combined with moisture during winter months causing a gel to form at the bottom. This starved the engine of oil, thus causing piston seziure or crank rod failure. 2-stroke oil formulas with versions 2 and 3 have evolved and thus have eliminated the problem.

2-stroke oils are not all the same, some have evolved over time according to the compression inside the cylinder (90 psi to 180 psi) and the amount of distance between the pistion and cylinder wall. Internal heat inside the pistion during explosion and material used in the manufacturing of the engine block also comes into play. Older engines around the 1970's were running on leaded fuel and tolerances of 10 to 12 thousands (.0010) to (.0012) respectively with compressions at 180 psi. Over the years of reducing the cylinder compression to (90 ~ 120) psi the fuel grade of octane has decresed and tolerances have been reduced to (.005 ~ .007). These tolerances have only been accomplished by the new aluminum/alloy advancement of the pistion and the cylinder wall called the sleve. Like metals at high temperatures would weld themselves together. New oils help prevent these different metals combinations to causing failure to the engine. Lower Octane increases the temperature inside the cylinder thus causing carbon buildup to occur between the piston and cylinder wall, this leads to scaring of the cylinder wall and pits in the pistion rings.


Items which can cause an engine to fail.

Basic 2-stroke engine funcition[edit]

Outboard engines for the most part run on a 12 volt DC battery. The flywheel has 2 devices that consist of a stator and trigger. If the flywheel was removed the the stator is outside the trigger. If you took the flywheel off and turned it over the stator would be related to the flywheel magnets on the outside and the trigger would be related to the 2 magnets on the inside of the flywheel where the crank shaft is attached. the stator works by many magnets on the flywheel passing by the coils built into the stator causing an AC wave output. This output is directed toward a set of bridged rectifiers (one way gates), capacitors, and voltage regulators; all converting the AC current to a positive DC current of ~13.5 volts, enough to chargs a 12 volt DC battery. Stators on engines are designed at different levels of amperage. Starting from 8 amp's to 35 amp's. The higher amp's have components that require water cooling to eliminate failure. The stator also sends AC current to the (Evinrude/Johnson) power pack or (Mercury/Mariner) trigger box. Evinrude/Johnson have only one pair of wires to each of the power packs. Mercury/Mariner have a red-pair and a blue-pair of cord output thus sending voltage to one side of the trigger box from start to 1500 rpm's and the other for rpm's above 1500 rpm. These power packs or triggers in turn charge the coils connected to the spark plugs and are computerized to fire in sequence according to the trigger under the flywheel. The power pack / trigger breaks the ground on the coil connections thus causing a short or spark. To turn an outboard engine off the power pack or trigger must have a ground tied to the key in order to disable the engine from running, otherwise running out of fuel is the other option.

Fire(spark), fuel, and compression are the 3 basic components to trouble shoot any issues with a engine. If you lack part or one of these then the engine will run poorly or not at all.

Some basic items to look for on outboards:

If you change the spark plugs and do not put the correct heat ratings designed for the engine or also do not set the gap to the correct settings the engine will perform poorly at high rpm's, sometimes low.

If the engine water impeller is not changed every 2 seasons, depending on use, the blades will set, crack and break thus causing a lack of water to move into the water cooling chambers of the engine around the heads. This could lead to causing rapid scaring and engine seizure because of over heating. The top cylinder is uaually the first to fail. Most engines have what they call tattle-tails, a stream of water comming out the back of the engine hitting the water. This is an indication of the pressure of water being supplied by the water pump.

The water pump is usually on top of what is called the foot and tied to the drive shaft. The drive shaft is tied between the engine crank shaft (item tied to the pistons by piston rods) and the lower gear box consisting of 3 gears. One gear is tied to the drive shaft that leads up to the engine (vertical). This vertical gear spins on top of the 2 horizonal gears tied to the propeller shaft. These gears spin freely on the propeller shaft, one spins clock-wise and the other counter clock-wise. A shift dog has teeth (male) on either side of itself and sits between the spinning gears (female). Slow the engine down enough and the shift dog teeth on either side can move on splines toward the forward gear or reverse gear, thus causing the propeller shaft to move (clock or counter clock)-wise. Be sure to never allow water to enter this gear area, failure of bearings and destruction of gears will result.

If you crank the engine as an example on land during flushing, usually after the engine has been subject to salt water envirnoments, have the foot oil checked by a mechanic to see if the oil is burnt or looks like a milk substance. Inboard/Outboard engines, usually 4 stroke have I/O drives which consist of 2 gear boxes. One plug is on top and one plug is on the bottom on either of these gear boxes. If you drain the foot oil, be very careful what type of drive oil is needed, brand only, and fill from the bottom squirting in the oil till it comes out the top plug hole. Change every year.

If oil and fuel sit inside carburators for a length of time; usually with oil fuel mistures or VRO's; then this results in what is called residue. This residue hardens over time and requires a wire brush to remove (not recommended) or carburator cleaner to disolve. With the advancement of carbon fiber plastic carburators it is almost impossible to see because they are black.

Engines that idle rough after warming up, has what is called spitting and sputtering - a rough idle - most are caused by carburators that are not all in alignment. A cam that rotates the trigger to advance the timming from 8-12 degrees before TDC (Top Dead Center) to 32 degrees controls the advancement of fuel on the carburators. Over time, some adjustments move or items wear differently from vibration of the engine at high rpm's. Fraction of inches matter in weather the carburators are fully closed at idle. Set screws on cams connected to carburators are the adjustments and a final roller adjustment to the trigger cam is required. Finding a mechanic to perform this is wise, because most of the time the engine requires the carburator adjustment while in the water with the hood off. when adding boost ports to lambretta engines the problem of reduced barrel wall becomes acute. snagging piston rings in ports becomes common if not boosted properly by a competent mechanic. i have just about perfected boost ports now after several attempts and the power increase is about 20% which makes a huge difference in the power for the small 200cc scooter engine. boost porting is all about free power, —Preceding unsigned comment added by Dadswizz (talkcontribs) 12:12, 24 January 2010 (UTC)

old messages[edit]

Somebody should join the pages two-stroke cycle and two stroke cycle - 2004/04/04 20:11 CET

Morven: (... removing part about 2 exhaust strokes since it didn't make much sense.)

it makes sense.. the noise an engine produces depends on the number of exhaust strokes. A two stroke engine has twice as many exhaust strokes as a four stroke engine (at the same rpm) and so produces twice the noise. MH 2004/05/06
But a 4 stroke engine will have more capacity for the same power, and thus will often have more cylinders, and thus the difference will be erased.
Except the 2 stroke burn cycle is interrupted by the exhaust cycle, while the 4 stroke completes the burn cycle before the exhaust cycle. iow, the fuel gases explode out of the chamger into the exhaust system.

Were there any 2-stroke diesels that were valveless? I've never heard of any, which must mean that at least it was rare. Any references, Andrewa? —Morven 20:13, 7 May 2004 (UTC)

There was a to-stoke diesel called Wichmann that were valveless, this was a big 2500 bhp diesel engine commonly used in the fishing fleet of Norway. (unsigned).

Also Crossley and Napier deltic diesels were valveless. Biscuittin (talk) 17:54, 27 December 2007 (UTC)

There were/are many tiny (typically 1.0cc) model aero engines which were compression-ignition valveless two strokes. Surely these count as diesels ? Cabinscooter 20:47, 18 July 2006 (UTC)
Not really, see model engine. Biscuittin (talk) 17:54, 27 December 2007 (UTC)
Disagree, they are compression ignition, liquid fuelled, reciprocating engines. Therefore in all essential respects they are diesel engines.Greg Locock (talk) 20:00, 27 December 2007 (UTC)

Does anyone have resources re: fuel efficiency/emissions of gasoline 2 stroke outboards? —Amgine

The "Basic Operation" section is contradictory. Does the air-fuel mixture enter the cylinder as the piston rises or as it falls? Also, a graphic would be most helpful.

Typically a bit of both, around about bottom dead centre. There's no induction stroke, nor an exhaust stroke. Instead these processes both occur independent of the piston movement, and overlap. That's the essence of the two-stroke cycle. Andrewa 17:07, 23 November 2005 (UTC)

bidirectional running causes damage not true[edit]

This passage. "It is true that Two-stroke engines will start and run in either direction, however running one in reverse will cause internal damage." is not correct. I have an Mercury outboard that uses "direct reversing." In other words it runs in both directions without causing damage. This was the first consumer straight six Mercury made and the chief engineer, Carl Kiekhaefer, was not sure a shifting gear case could take the increased horsepower. To get around this he merely had the outboard run forward or backward. William (Bill) Bean 14:56, 21 November 2006 (UTC)

Although it wont cause damage on engines designed to do it, it can over time cause problems with an engine not designed to run backwards for the reasons stated in the article. When designed to do so there is no problem at all.--=Motorhead 23:36, 21 November 2006 (UTC)

reference for 2 stroke emissions[edit]

-Design and Simulation of Two-Stroke Engines Gordon P. Blair -The internal combustion engine in theory and practice by C.F.Taylor -Internal combustion Engines and Air Pollution by Edward E. Obert --=Motorhead 19:38, 1 Apr 2005 (UTC)

Bombardier and Rotax both have direct-injection marine outboard 2-strokes that run on straight gasoline and meet the strict California Air Resources Board emission standards. Information about this technology might be a useful addition to this article.

Reed valve[edit]

Can these be made of fibers alone, or are the fibers always bound into a resin to form a composite material? If the latter is the case, please re-link from carbon fiber to graphite-reinforced plastic. You might also want to do the same for glass fiber, re-linking to glass-reinforced plastic.--Joel 03:09, 16 Jun 2005 (UTC)

Use of both valves and ports in one engine[edit]

See the graphic at How Stuff Works for a design with inlet ports in the sides of the cylinders, and exhaust valves in the head. It looks very credible to me, but we don't describe this variation at all, in fact we more or less imply that it's one or the other. Who is right? Andrewa 17:07, 23 November 2005 (UTC)

The arrangement shown on the link you supplied is described in the “Valve in head” section. The fact that the ports are in the cylinder sidewall is assumed because that’s the only place they can be. The engine type is used by detroit diesel and others.( 06:46, 28 November 2005 (UTC)

Not so. There could be both inlet and exhaust valves in the cylinder head, and no ports at all. That's what I assumed this section was describing, and I still think it's the more natural reading of the section as it stands. Andrewa 09:58, 28 November 2005 (UTC)

Link above corrected to point to version before changes - Andrewa 09:54, 12 December 2005 (UTC)

There is no case I am aware of which uses both intake and exhaust valves in the head for a 2 stroke engine. The problem of scavenging would be nightmarish with such a system but I wouldnt doubt that someone somewhere tried it without success. The intake and exhaust have to be open at the same time in a 2 stroke. There is no system in operation which can have both intake and exhausts in the head and be open at the same time and still scavenge with any reasonable efficiency. The valve in head may be intake or exhaust but not both. I think you are confusing 4 stroke diesels with 2 stroke diesels. The only "natural" reading would be to assume uni flow , cross flow or loop scavenged flow when considering a 2 stroke engine, as all systems fall into these 3 types. In all cases there are ports in the cylinder wall.--=Motorhead 04:01, 6 December 2005 (UTC)

Exactly. I think your new version eliminates this confusion, which is common elsewhere on the www, not just on Wikipedia. Thank you! Andrewa 09:54, 12 December 2005 (UTC)
Hmmm. Perhaps one reason for this confusion is that the first two-stroke engines were Clark cycle diesels, which have no ports in the cylinder walls, see Dugald Clark. Perhaps all modern two-stroke engines (whether diesel or not) do have cylinder wall ports, but these first ones did not. The article still seems to need some work IMO to make this clear - if I've finally got it sorted out! Andrewa 16:23, 16 December 2005 (UTC)

I havent been able to find much detail on Sir Dugald Clerk's (not Clark) engine except that it used a second cylinder to pump fresh mixture through a one way valve into the working cylinder. Nevertheless, at least from the time of Alfred Scott and Day,cylinder sidewall ports were used.--=Motorhead 18:42, 18 December 2005 (UTC)

If the title of the Dugald Clark article is wrong, please fix it, or at least cite your sources and I will.
Frankly, there's a lot of misinformation about engines of all sorts (steam, gasoline, diesel, proposed) on the web. Many engine enthusiasts (I may even be one of them!) seem to write webpages, including Wikipedia articles. It's easy to pick up folklore from people who specialise in one particular type of engine, and assume for example that all two-strokes are the sort that they know intimately, or that all V-8 engines are crossplane. I'm currently looking closely at every v-twin motorcycle I see (and I see lots in my current work) to try to come up with the best set of examples for that article... it's a lot more complicated than many think! I think however that the inline twin article is mainly sorted out.
There's also a certain amount of deliberate misinformation spread by engine and vehicle manufacturers and proposers of new designs, and going back several centuries!
But I think we are making progress here. Andrewa 20:21, 20 December 2005 (UTC)

I put some sources in the talk page of the Clark page.Its a very widespread error but I think the Clerk sources have it. Vtwins? I'd definately include early harley and must have vincent maybe indian. I'd include that the vtwin was an offshoot of the WW1 radial design with most of the cylinders missing!

I guess all we can do is our best. Myths really annoy me and they spread faster than real facts do. Today I heard from my bro-in-law about adding acetone to your gas for a miraculous milage increase of 35%! (like no one ever tried that eh? hehe) never ends--=Motorhead 03:31, 21 December 2005 (UTC)

AFAIK the big shallow-V twins such as Harley and Crocker are well covered by what the article already says. The myth that needs exploding is that all v-twins are this common big-end configuration. The Yamaha Virago, for example, has an enormous offset between the cylinders, strongly suggesting a double-throw crank, but I've yet to find any citeable source that describes its internals. Andrewa 10:09, 21 December 2005 (UTC)


I think this page needs a general refactor. The headings overlap, particularly on diesel engines. We need a clearer structure. Andrewa 01:48, 25 December 2005 (UTC)

I've started this with a new history section. More to follow. The diesel engine article also needs some work. Andrewa 20:56, 25 December 2005 (UTC)


could someone find a bigger graphic of the two stroke engine with color to show the gas?

Crap article[edit]

This article has been edited into garbage! It is now a mere thumbnail definition instead of an informative article. Someone has to go back through the revisions and restore the plentyfull information that was here and now is gone.

Outboard Motors[edit]

I changed 'small outboard motors' to 'outboard motors' in Applications. Yamaha currently makes a 300hp 2-stroke, Mercury makes a 250hp, BRP makes a 250hp and Tohatsu's largest, a 115hp, is also a 2-stroke. Their small outboards are almost universally 4-stroke. So this would seem to be an obvious error.

This article makes no mention of direct fuel injection, which is is a serious omission since it is clearly necessary to the future of 2-stroke engines. The emissions info also appears to be out of date. EPA awards '04 Paul Moir 20:52, 5 March 2007 (UTC) 00:35, 13 April 2007 (UTC)

Tuning a Chain Saw[edit]

If I have a chain saw and it has idle, Lo and High adjust. The engine starts and roars to life only to be suffocated by the brake. I frantically adjust all the screws and nothing happens except it dies out, when I turn it too far. High throttle all the time. How can I adjust it nicely to hum and the throttle can actually be used.

First you must insure the idle speed is adjusted correctly. Sounds like your throttle is open too far even at idle. Could be idle speed much too high or throttle simply stuck open. Check to see that the Throttle butterfly actually closes all the way(NOT the choke butterfly). Then gently close high and low speed mixture screws and then open each about 1 1/4 turns and adjust the idle speed so the throttle just begins to open for a start. If you have a manual use those numbers instead. For the saw to rev as you decribe it must have air and its getting it from somewhere. --=Motorhead 16:13, 13 April 2007 (UTC)

Two stroke outboard oil injection leakage[edit]

My 30 HP Yamaha outboard (3 cylinder) has currently extensive oil leakage in the lowest carborator. It literally has oil coming out of the carborator intake and I have no idea where it comes from. What might be the cause?

Schnürl porting[edit]

I'm not sure if [24] should be on the links list, but it explains Schnürl porting as having the transfer and exhaust ports "overlap" in timing, to use the term for the 4 stroke equivalent. Other sources, such as [25] say that it is multiple "focussed" transfer ports, or the like. (Good thing it wasn't used soon after the patent. It would have been a headache for the patent office and courts.)


the article missing "Future of Two stroke Engines" after the pollution issues.there is one company in australia afaik which offers solutions regarding the polluting part ,IIRC it is called "orbit" .Praka123 (talk) 23:27, 12 October 2008 (UTC)

Sierra club full of it[edit]

I'm pretty sure that the Sierra club's claim that 8 hours of a jetski running will pollute more than a car going 100k miles is absolute crap. I'll say that a jetski consumes an incredible 50 gallons of fuel in 8 hours. The real number is much less, but 50 makes it even. Assume a car with a more-or-less average fuel economy, say 20mpg over it's 100k miles. At 100k miles that's 5000 gallons. I'm not sure that it's possible for the cleanest-burning engine to burn 5000 gallons and put out less pollution than the dirtiest engine burning 50 gallons. Even with 2-stroke oil in the mix (35:1), that's about a gallon and a half of oil, total. With the Sierra club figure or 30% going unburned, you get 15 gallons of gasoil unburned. Does the Sierra club honestly mean to say that 100000 miles of driving puts out less pollution than 15 gallons of fuel? Come on now. They're smoking something. Probably they compared the jetski to a solar car and didn't bother to include that detail. Phasmatisnox 05:56, 20 August 2007 (UTC)

Your opinion and open bias are sure to get your changes made!Athene cunicularia 14:28, 20 August 2007 (UTC)
Suddenly, having a strong opinion has become wrong. Interesting. Phasmatisnox 02:46, 21 August 2007 (UTC)

There is reason of some sort here. For carbon dioxide, obviously the car is much worse, but an engine too small to come under regulation might produce very much more of the hydrocarbon emissions that are so carefully controlled in cars. David R. Ingham (talk) 06:22, 29 November 2010 (UTC)

mercury 2 stroke engine[edit]

I have been told that if 2 stroke fuel is left in the tank for a period of about 3 months or so that the oil in the mixture can separate and restrict fuel flow in the system and make starting etc difficult, is this true? I have just bought a second hand engine and even after changing the plug it is difficult to start. Compression seems OK. Advise welcome. —Preceding unsigned comment added by Jakey77 (talkcontribs) 09:21, 2 September 2007 (UTC)

Hello my name is Blake Carlson

This is cool thanks —Preceding unsigned comment added by (talk) 19:03, 30 October 2007 (UTC)

My model airplane fuel containing cater oil got very thick (viscous), after sitting for years, and would not go through the needle valves. David R. Ingham (talk) 06:29, 29 November 2010 (UTC)

Why no small two-stroke diesels?[edit]

Ok so I understand why we don't use two-stroke gasoline powered cars anymore (Trabant), but why can't I have a two-stroke diesel in my Jeep? It seems that two-stroke diesel technology shows up only in large scale diesel engines, but if the pollution problems don't exist as they do for two-stroke gassers, then whats the hold up? Every article I have read (including this one) gives no explanation why, it only states that two-stroke diesels are large and four-stroke diesels are small (relatively speaking). Madzyzome (talk) 17:57, 21 May 2008 (UTC) diesel and gasoline engins should be discussed seperately LUB Two-stroke gasoline engines etc. (talk) 06:43, 10 June 2008 (UTC) wdl

Two cycle have roughly only 1.7x power of a 4 cycle engine of the same size.Further it needs an airpump preferably supplying excess air,more than a crankcase can supply. The porting lubrication combination is difficult in a small diesel .The two cycle diesel trunk piston has to be longer to cover the ports and have piston rings and oil scraper rings at the bottom also to keep excessive oil in the crankcase.Gasoline (/petrol brt.) 2 cycle have lube oil in the fuel and have other problems. The layout of a large crosshead diesel is different and have separate cilinder lubrication from the crankcase. Anybody with more info???wdl24.146.23.84 (talk) 18:51, 20 October 2008 (UTC)

I don't have a good answer for car and motor-cycle applications, it maybe due the small(er) powerband which would imply needing either a short-geared or continus-automatic transmission system with them. The motors do exist though, and are somewhat popular for ultra-light planes etc. /me likes this design fwiw:

My guess is that it's practicable to put a super-charger on a big motor but not on a small motor. Without a super-charger then the lubrication is total-loss and inevitably polluting. MalcolmMcDonald (talk) 15:51, 30 April 2009 (UTC)
Well 4-strokes leak/burn (very little, but still) some lubrication oil at least from the piston/cylinder film too. Theoretically, provided stationary operation, an only air scavenged 2-stroke shouldn't do much worse. With proper (electronic?) management i don't see why the 'stationary' part cannot be made dynamic enough to an extend. In case i'm incorrect and indeed a wet-sumb roots-blower setup is truly required; it may just be less of an effort, or expense, to turbo a 4-stroke and get similar performance.
Interesting things going on with small plain engines from about 100 up to +- 400hp most 'new' models are turbo-charged/inter-cooled opposed-piston two stroke diesel engines; such as (like a downscaled —Preceding unsigned comment added by (talk) 11:29, 1 May 2009 (UTC)

Lubrication of two cycle gasoline engines[edit]

wdl Two-stroke gasoline engines often have a simple lubrication system in which a special two-stroke oil is mixed with the fuel, (then known in the UK as 'petroil' from "petrol" + "oil") and therefore reaches all

FACT OIL-GASOLINE YES .OIL- DIESEL NO WAY.wdl —Preceding unsigned comment added by (talk) 04:23, 18 October 2008 (UTC)

Yes, I agree. what is this wdl thing you do - is it your sig? It should not appear in article space. Greg Locock (talk) 04:27, 18 October 2008 (UTC) I dont need the credit just fix the problem . i am getting an account.wdl dear loco. ok mix lub with bunker c -known as tar. good luck and use a blowtorch or real hot air.wdl —Preceding unsigned comment added by (talk) 05:42, 18 October 2008 (UTC)

large engines[edit]

""""Early two-stroke Diesels using the crosshead layout (where the cylinder is not integral with the crankcase) employed under-piston pressure to provide scavenge air to the combustion chamber via a bypass port as used on a conventional gasoline-fueled two-stroke engine. Although the cross-head layout is still used on some large engines, greater power and efficiency, as well as lowered exhaust emissions, can be obtained with a mechanical blower or turbocharger.""""

Large low rpm (100- 400)diesel engines have crossheads.There are none that use the bottom part for scavenging. Mechanical blower , turbocharger and tandem piston pumps have been used.wdl24.146.23.84 (talk) 05:38, 21 October 2008 (UTC)

two stroke[edit]

User talk:Raymondwinn (section). looked at your revisions . care to look at diesel egines also?it needs lots of help.Wdl24.146.23.84 (talk) 18:48, 3 November 2008 (UTC)Wdl24.146.23.84 (talk) 18:58, 3 November 2008 (UTC)

Retrieved from "" ViewsWdl24.146.23.84 (talk) 18:59, 3 November 2008 (UTC)

The two-stroke diesel promises to be the engine that's going to take the automotive industry into the next chapter burning biodiesel fuel.--Timpicerilo (talk) 03:19, 2 November 2009 (UTC)

every two stroke engine will give power —Preceding unsigned comment added by (talk) 03:25, 3 March 2010 (UTC)

self promo[edit]

to inventor
you got great ideas but do not put them in wrong places. it is impolite.keep doing it is rude .Wdl1961 (talk) 19:57, 12 November 2008 (UTC)

I don’t sell anything, ergo there is no "self promo". There are several "proposed engines", even with an extra site. It would be non-neutral if all are allowed but only this one not.

I have a small paragraph only. See also the discussion above. And please be polite - and stay away. Thanks --Wolfhart Willimczik - Physicist & Inventor 20:15, 12 November 2008 (UTC) —Preceding unsigned comment added by Inventor (talkcontribs)


Honda has worked around this difficulty in their mini four-stroke engines.
not two strk Wdl1961 (talk) 06:34, 12 December 2008 (UTC)

Ski doo has developed fuel injected two-stroke engines for their snowmobiles that out perform the four-stroke in every way including emissions and mileage.--Timpicerilo (talk) 03:14, 2 November 2009 (UTC)
You would need super-reliable sources to use this astonishing fact in the article. MalcolmMcDonald (talk) 11:47, 17 January 2010 (UTC)
Is the EPA a reliable enough source for this "astonishing" fact? Junior33 (talk) 01:38, 8 April 2010 (UTC)

Piston controlled inlet and exhaust in opposed piston engines[edit]

In an opposed piston engine one of the opposing pistons in a cylinder controls the exhaust port and the other controls the transfer/inlet port. Some engines have a slight angular offset between the top and bottom crankshafts to achieve early exhaust before scavenging.[1]

uniflow duplication removedWdl1961 (talk) 04:52, 30 December 2008 (UTC)

Disagree with removal of link[edit]

The "the fuel and engine bible" was removed with this edit and I'm afraid I disagree and am putting it back. The downside to sending people to this web-site (which claims to have sponsors and maybe multiple inputs?) is that the guy sets a writing standard we may struggle to meet. I can't tell if this link has been removed from other articles but it's possible and if so, I might be tempted to chase round and put it back there as well. But I'll not do that now. MalcolmMcDonald (talk) 11:17, 1 January 2009 (UTC)

I removed it, and I removed it from many other articles too. While there appears to be a decent amount of information, there's no credibility behind it. According to the site, it's run by one guy (Chris Longhurst) who likes to add it to any articles he can find. That makes it a self-published source not matching the WP:RS standard. Now, according to this note, it could stay, I suppose. I'm just bothered that it has been spammed by the author himself to a plethora of other pages- which seems to violate rule #2 on the "using self-published .. as sources on themselves" rule. tedder (talk) 15:33, 1 January 2009 (UTC)
Do you have reason to believe it's the author who has put it in? I'm not connected in any way, it just seemed that it added real benefit to readers. MalcolmMcDonald (talk) 17:48, 1 January 2009 (UTC)
The user who has been adding the link is Chrislonghurst. The carbible site has a copyright on the bottom that (effectively) says "copyright Chris Longhurst. Of course, the fact that you (someone not connected) thinks it is useful means something- but it still doesn't meet the verifiability rule, does it? Certainly it's not a clear-cut case, which is why we are discussing it! tedder (talk) 00:21, 2 January 2009 (UTC)
carbibles is not reliable or authoritative. It discusses a system with which I am very familiar indeed (ie I designed or developed many parts of it and am still responsible for it). He doesn't know what some bits do AND JUST MAKES STUFF UP. So, I will be removing all references to carbibles. Greglocock (talk) 11:14, 2 January 2009 (UTC)

It would have been nice for you to contact me directly rather than just post such comments behind my back. I'd be happy to make any corrections you think necessary (probably to control blade suspension) - I rely on comments and input to keep my site current. I was simply placing links for wiki readers to get further information. As it happens, my site has been linked from wiki by people other than me before, and I was simply replacing links that had been removed over the course of the previous year or so. The 80's Kid (talk) 21:02, 2 January 2009 (UTC)

Hi Chris, note that I put a warning on your page about it. No matter the details of how or when it was removed, it still appears to meet the self-published source and doesn't meet the WP:RS rule. tedder (talk) 21:07, 2 January 2009 (UTC)

I saw the note afterwards - sorry. I can accept the self-published rule - at least it's a valid explanation. The offer is still there to fix whatever you think I've got wrong though.... The 80's Kid (talk) 21:09, 2 January 2009 (UTC)

I didn't write to you about correcting your site because that is not my job. In fact, could lose my job if I did so. But for a start, a shock absorber does not absorb shocks. Any suspension book that I have read points that out. Greglocock (talk) 23:03, 2 January 2009 (UTC)

Advantages and disadvantages[edit]

I added some of the much needed information over the pros and cons of the two-stroke.--Timpicerilo (talk) 12:57, 18 April 2009 (UTC)


In the "Reversibility" section, why does the ATDC link go to the "Advanced Technology Development Center" and how does this relate to BTDC?

I've removed that part of the article, which was incorrect anyway. MalcolmMcDonald (talk) 11:45, 17 January 2010 (UTC)

add future of 2 stroke:[edit]

Please add future of 2 strokers(especially biker fans wants to know) and how they can be made efficient.there are many technologies available.Australia's Orbital pioneers in add "Future" section. thanks. —Preceding unsigned comment added by (talk) 16:26, 16 August 2009 (UTC)

Fuel injected two-strokers are almost as clean as a four stroke.--Timpicerilo (talk) 04:00, 24 October 2009 (UTC)

Some of mension of new developments where removed before; such as: and (talk) 19:42, 15 November 2009 (UTC)

A section on two-stroke pollution is needed![edit]

Two strokes present many environmental problems affecting the health of people all over the world. Such important issues and inherent problems with two-stroke technlology need to be front and center, not minimalized as this article presently does. Theaternearyou (talk) 19:54, 6 September 2009 (UTC)TNY

I've participated in experimenting with burning an alcohol vegetable oil mix that produced more horsepower than gas with good emissions results. So if you don't mind smelling like french fries the light weight high power two-stroke may be the answer to our pollution problems. Bio fuels can also be used to mix with gas creating a virtually smoke free two-stroke.--Timpicerilo (talk) 03:58, 24 October 2009 (UTC)

Two-strokes in ship engines[edit]

I know very little about two-stroke ship engines but will accept they may be reversible. However, they probably have at least one poppet valve like a four-stroke and, if they're reversible, they probably have a valve-lift modifying mechanism on the camshaft.
With sufficient information from a knowledgeable source, properly cited, then it would probably be in order to mention starting, compressed air and multiple cylinders. Without such an in depth discussion there is no reason to include anything so peripheral. Even the existing sentence (with "Fact" tag) is dubious to include, but it may encourage an expert to comment. MalcolmMcDonald (talk) 11:55, 17 January 2010 (UTC)

All large diesel freight ship engines are reversible and air started either way.Camshaft timing is changed if req. Motor cycles runing backwards are not common around here. pls do not rev common knowledge.Wdl1961 (talk) 15:00, 17 January 2010 (UTC)
Prove what you're saying about ship engines, with a proper discussion of the engineering modifications which make reversible running possible. In paragraphs that explain the running of ship engines, mention of their starting, the compressed air necessary and multiple cylinder engines may be valuable, otherwise it is not. Please be careful to include reverseability of four-stroke engines only where it is directly relevant and adds materially to the discussion of two-stroke engines. MalcolmMcDonald (talk) 15:21, 17 January 2010 (UTC)
Read standard ship deisel eng handbook pls.Wdl1961 (talk) 16:01, 17 January 2010 (UTC)
Bring acceptable reliable sources to the edits you want to make. If you're not willing to contribute edits it might be better to remove all references to the reversability of ship engines until we have editors who are prepared to do so. Spelling and grammar need not be an obstacle, there are many editors prepared to help. MalcolmMcDonald (talk) 16:33, 17 January 2010 (UTC)

2 stroke engine[edit]

as it is written in 2 stroke engine {A two-stroke engine is an internal combustion engine that completes the thermodynamic cycle in two movements of the piston} can we write process cycle or engine cycle instead of thermodynamics cycle?? because by definition thermodynamic cycle is defined as the series of processes through which the working fluid progresses and eventaully return to its original state or thermodyamic cycle implies a closed cycle system wiyh no exchange of matter with the surrounding. i.c. engines do not operate on thermodynamic cycle because they operate on open cycle {they exchange matter with the surrounding means take fresh air for each new cycle and exhaust the same after burning}burned gases of exhaust can not be use again as fresh air .hence exchanging matter with the surrounding continously.{nuski.ishrat}-- (talk) 17:39, 24 March 2010 (UTC)

I think I agree, in fact I will make that change. I am not sure exactly how general thermodynamics is. People talk about non-equilibrium thermodynamics, but it can't cover everything that is happening. David R. Ingham (talk) 06:39, 29 November 2010 (UTC)

Diagram of the phases in the two-stroke cycle[edit]

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[edit] Summary Description Ciclo del motore 2T.svg Deutsch: Schematische Darstellung der Phasen in einem Zwei-Takt-Motor 1=OT, 2=UT A= waschen, B= Entlastung, C= Kompression, D= Expansion English: Diagram of the phases in the two-stroke cycle 1=TDC, 2=BDC A= wash, B= Exhaust, C= Compression, D= Power Français : Schéma des étapes dans un moteur deux temps 1=PMH, 2=PMB A= de lavage, B= Décharge, C= compression, D= extension Italiano: Diagramma di distribuzione delle fasi nel motore a due tempi 1=PMS, 2=PMI A= Lavaggio, B=Scarico, C= Compressione, D= Espansione Date 14 December 2008(2008-12-14)

Source Own work

Author A7N8X

Permission ( Wdl1961 (talk) 21:49, 5 April 2010 (UTC)

The animated drawing Arbeitsweise Zweitakt.gif[edit]

It is not clear why there should be a massive reverse expulsion through the intake. Cuddlyable3 (talk) 11:31, 16 April 2010 (UTC)

obviously the drawing is not 100% correct at all speeds, but --..Wdl1961 (talk) 14:29, 16 April 2010 (UTC)

Basic information missing[edit]

This article has been written by people who know a lot about engines. Unfortunately this means that basic information is missing because "it's obvious - everybody knows that."

As a non gear-head, I was left little wiser for having read it, because it gets into discussion of differing designs after the most cursory description of the basic function, and I found that really confusing.

Compare that to the 4-stroke article which carefully explains the theoretical functioning of the engine before getting into real-world design minutiae.

for example I wanted to know: What's the difference between stroke 1 and stroke 2? Is a stroke the piston moving from the top to the bottom of the chamber (or vice versa), or is a stroke the complete movement of the piston until it returns to its original position?

Pinkmouse (talk) 10:38, 13 June 2010 (UTC)

I have attempted to respond to this. David R. Ingham (talk) 06:10, 29 November 2010 (UTC)

Cycle vs Stroke[edit]

I am trying to get clarification on Cycle vs Stroke, as it seems even here on Wikipedia the distinction is ambiguous.

My understanding is the Cycle and Strokes of an engine are separate aspects of it's design.


The thermodynamic cycle by which an engine operates to convert heat into work.

1. Otto - or spark ignition combustion cycle [2] 2. Diesel - compression ignition. 3. Atkinson - variation on the Otto. 4. Miller - variation on Otto. 5. Brayton - combustion turbine.


The number of piston strokes to complete a cycle in a reciprocating engine.

1. 2-stroke. 2. 4-stroke. 3. 6-stroke.

Otto engines can be 2 or 4 stroke, so can diesels.

Perhaps the terms are in reality not well defined, since Otto basically patented a 4-stroke spark ignition engine, based on inspiration 2-stroke spark ignition engine [3] and [4]

I argue since a diesel can be 2 or 4 stroke, and diesel is a cycle well defined as not being an otto cycle, that the number of strokes is independent of the cycle of an engine and that a spark ignition two stroke would be considered a otto cycle engine. —Preceding unsigned comment added by Justinharrell (talkcontribs) 17:01, 17 July 2010 (UTC)

Name change ?[edit]

The following discussion is an archived discussion of the proposal. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section.

The result of the proposal was consensus against move as an uncommon and overprecise alternative.--Fuhghettaboutit (talk) 22:22, 2 August 2010 (UTC)

Two-stroke engineTwo-stroke internal combustion engine — I'm not sure about this article, but it seems to me that this article is enterily based around internal combustion engines. If not, the article needs a cleanup (ie first line is already very incorrect then), and other engine types need adding; if it is, change the name. KVDP (talk) 11:01, 26 July 2010 (UTC)

No. This is the common name by which it's known.
As a second point, please stop putting forward "helpful" suggestions to topics on which you regularly demonstrate yourself to be thoroughly ignorant. We have quality standards on this project, I wish you would pay some respect to them yourself. Andy Dingley (talk) 11:13, 26 July 2010 (UTC)
Reject. Current title is more concise, sufficiently precise, and currently widely used without ambiguity. StuartH (talk) 13:06, 26 July 2010 (UTC)
The above discussion is preserved as an archive of the proposal. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Bad Name[edit]

The term "stroke" has to do with the distance the piston travels. The proper term for this type of ICE is "two-cycle", as opposed to a four- or six-cycle engine. Please correct. - KitchM (talk) 22:19, 28 May 2011 (UTC)

WP:COMMONNAME would over-ride this, as would Phil Irving's 'Two-Stroke Power Units', Ricardo, and many other good refs. Andy Dingley (talk) 09:55, 29 May 2011 (UTC)

The picture that says "A two-stroke minibike" is not accurate and it belongs to a 4 stroke engine mini pit bike[edit]

2 stroke engines have a muffler with an expansion pipe (something like a belly in the muffler start). The picture under that name is 4 stroke for sure. I actually own one REALLY similar. Just trying to improve. — Preceding unsigned comment added by (talk) 03:28, 25 December 2011 (UTC)

It looks to me like Foxico minibikes have the expander on the left side, downstream from the U shaped pipe visible in the image: [26] --Dennis Bratland (talk) 03:56, 25 December 2011 (UTC)

Merge of Two-stroke diesel engine:[edit]

English variant[edit]

I am American. I use American English when contributing, but for the most part, I simply want articles to be 1: readable for all users; and 2: internally consistent. I've reverted changes from British English to American English and vice versa when these changes have been against style recommendations, and have changed British terms that Americans would be hard-pressed to recognize into universal terms, though I'm not as well-equipped to do the reverse. My edit history (at least as far as I can recall) will bear that out.

All that said, this article has no especially strong intrinsic tie to one variant or another, but American English was established long ago before it was slowly mixed, and then, judging by a few edit summaries going back (I went through the history to identify major changes), a few misguided editors apparently began to believe that it was British English that had been established. It really doesn't concern me except that the article should not be constantly revised in favor of one variant or another.

I believe American English was firmly established and I think that's how it should remain. British terms like "petrol" should, of course, be introduced alongside the American ones, but then the American terms should be favored for consistency and simplicity. If there are no objections, I suggest adding the {{American English}} template to this talk page. (talk) 16:35, 25 May 2015 (UTC)


These are banned in China and some other countries, right? --JWB (talk) 05:53, 29 December 2015 (UTC)

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